A Dissertation Entitled Bio Based Active Barrier Materials And

Home , Acetanilide, Linoleic acid

A Dissertation

entitled

Bio Based Active Barrier Materials and Package Development

Michael Angelo Miranda

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the

Doctor of Philosophy Degree in

Engineering

______Dr. Maria. R. Coleman, Committee Chair

______Dr. Saleh A. Jabarin, Committee Member

______Dr. Sridhar Vimajala, Committee Member

______Dr. Yakov Lapitsky, Committee Member

______Dr. Young- Wah Kim, Committee Member

______Dr. Amanda Bryant-Friedrich, Dean College of Graduate Studies

The University of Toledo December 2016

This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of

Bio Based Active Barrier Materials and Package Development

Michael Angelo Miranda

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Engineering

The University of Toledo

December 2016

The food and packaging industries are interested in approaches to reduce the permeability of oxygen in polyethylene terephthalate (PET) to extend the shelf-life of product. This has led to considerable research in barrier improvement including the use of active scavenger that permanently bind oxygen. The purpose of this work is to investigate the use of renewably sourced unsaturated fatty acids as scavengers to reduce the O2 permeability in PET. Specifically fatty acids were characterized and incorporated within

PET using both blended and reactive extrusion to analyze the impact on thermal- mechanical and oxygen transport properties.

Oleic, linoleic and linolenic acid are renewably resourced unsaturated fatty acids that are being investigated as active scavenger. Utilization of scavenger capacity and kinetics of oxidation are two key parameters that must be considered while selecting a scavenger. The O2 uptake capacities and the utilization of scavenger sites analysis were used to determine the most appropriate scavenger used to make a copolymer with PET.

Linoleic acid was chosen due to its higher utilization capacity and relatively fast kinetics

iii the cost was also taken into account. Thus linoleic acid was used in preparation of

PET/Scavenger system.

The effect of addition of unsaturated fatty acid on the thermal, mechanical properties and morphology of PET, were analyzed by preparing blends of PET/linoleic acid of loading of (0.25-2 weight %). The presence of the scavenger were analyzed using end group analysis where an increase in carboxyl end group was determined and NMR to obtain the peaks for the fatty acid. The appropriate method to determine molecular weight was also established. Effects of permeation through amorphous and biaxial oriented films with and without linoleic acid were investigated.

The bottles were produced in two different ways (i) reactive extruded bottle and

(ii) blended bottles (0.5% weight loading of Linoleic acid). The mechanical properties and density of the bottles were similar. The oxygen permeability of these bottles side wall was lower than that of PET. NMR on sample that has been exposed to oxygen was conducted to confirm the reactivity of linoleic acid with oxygen.

To my parents, brother and family

Acknowledgements

My heart felt gratitude to my advisors Dr. Saleh. A Jabarin and Dr. Maria

Coleman for having given me the opportunity to work in the Polymer Institute. Their constant guidance through the entire work helped me understand the polymeric systems and I appreciate their willingness to listen to my thoughts and complaints. Thanks are also due to the members of the PET and Active barrier consortium for their financial support and inputs throughout this project, also to the Department of Chemical

Engineering of the University of Toledo for all the support that I received.

At this point, I also would like to thank Ms. E.A Lofgren for training me on the finer aspects of various instrumentations and her constant inputs at the early stage of my work. Many thanks are due to Mr. Mike Mumford for his support, in teaching and helping me prepare various forms of PET products along with helping me understand how the different devices worked. I also extend my thanks to Dr. Lawrence, Dr. Avalos and Dr. Rodrigues for their support with instrumentation at CMSC, to Dr. Kim at the

NMR center for helping me with NMR and for being on my Ph.D. committee. I am grateful to Dr. Lapitsky and Dr. Vimajal for having agreed to be members in my Ph.D. committee sparing valuable time in reviewing my Ph.D. work.

Thanks to all my colleagues at the Polymer Institute and the Chemical

Engineering Department for making work in the lab an enjoyable and an intellectual experience. Living in Toledo has been so memorable and enjoyable due to my friends without whom it would not have been the same. Last but not least I would like to thank my family for being my strong pillar of support throughout my Ph.D. program. v

Table of Contents

Abstract ...... iii

Acknowledgements ...... v

Table of Contents ...... vi

List of Tables ...... ix

List of Figures ...... xiv

List of Abbreviations ...... xxi

1. Introduction ...... 1

1.1 Hypothesis ...... 7 1.2 Research Objectives ...... 7

2 Literature Review ...... 10

2.1 Permeation ...... 11 2.2 Passive Oxygen Barrier ...... 14

2.2.1 Coating ...... 14 2.2.2 Nanocomposites ...... 15 2.2.3 Polymer Blends: ...... 18 2.2.4 Multilayer Films...... 19 2.2.5 Additives that affect free volume ...... 20 2.2.6 Crystallization and branching ...... 21 2.2.7 Copolymers ...... 21

2.3 Active Oxygen Barrier ...... 22

2.3.1 Sachets ...... 24 2.3.2 Amosorb ...... 26 vi

2.3.3 Oxbar systems ...... 30 2.3.4 Other oxygen scavenger systems...... 33

2.4 Rate of scavenging in polymers ...... 35

2.4.1 Thiele modulus...... 35 2.4.2 Selection of renewably sourced scavenger ...... 37

2.5 Reactive Extrusion ...... 39 2.6 Barrier Improvement Factor (BIF) ...... 40

3. Material and Methods ...... 43

3.1 Materials ...... 43 3.2 Methods ...... 46

3.2.1 Oxygen scavenging ...... 46 3.2.2 Preparation of PET/LA systems...... 49 3.2.3 Preparation of Bottle ...... 52 3.2.3.1 Injection molding ...... 52 3.2.3.2 Stretch Blow Molding ...... 53 3.2.4 Orientation of samples ...... 54 3.2.5 Characterization methods...... 56

4. Oxygen scavenging capacity and kinetics ...... 70

4.1. Oxygen scavenger capacity ...... 70 4.2. Confirmation of the mechanism of oxidation ...... 79 4.3. Kinetics of Oxidation ...... 81 4.4. Kinetics under diluted conditions...... 86 4.5. Calculation of Thiele modulus ...... 88 4.6. Conclusion ...... 90

5 Bottles Blown with PET/ LA ...... 92

5.1 Presence of LA within PET ...... 94

5.1.1 Solution NMR of Bottle Sidewall ...... 94 5.1.2 End group concentration ...... 99 5.1.3 Migration of Linoleic Acid ...... 102 5.1.4 TGA ...... 104

vii

5.2 Characterization of PET/ LA systems ...... 108

5.2.1 Melt IV ...... 108 5.2.2 Thermal –Physical Properties of PET/LA systems ...... 109 5.2.3 Oxygen permeation ...... 112

5.3 Conclusion ...... 114

6. PET Blends and Terminated with LA ...... 116

6.1. Presence, nature and quantification of LA within PET ...... 119

6.1.1. NMR ...... 119 6.1.2. End group ...... 125 6.1.3. TGA ...... 131

6.2. Characterization of PET/ Linoleic acid systems: ...... 133

6.2.1. Density ...... 133 6.2.2. Differential scanning calorimetry (DSC) ...... 136 6.2.3. Intrinsic Viscosities ...... 143 6.2.4. Oxygen permeation ...... 147 6.2.5. Confirmation of reaction of Linoleic acid with oxygen ...... 156 6.2.6. Potential cases for reduction in oxygen permeation ...... 158

6.3. Conclusion ...... 161

7. Conclusion ...... 163 8. Future Work ...... 169

8.1. Microstructure of PET/oxygen scavenger systems ...... 169 8.2. Potential oxygen scavengers ...... 170 8.3. Linoleic acid as catalyst ...... 172

8. Reference ...... 174 A. Appendix ...... 195

viii

List of Tables

Table 2-1: Oxygen permeability of various polymers [68] ...... 18

Table 2-2: Commercial oxygen scavenger available in market...... 23

Table 3-1: Properties of the scavenger ...... 45

Table 3-2: Blow molding heaters voltage outputs...... 54

Table 4-1: Conditions used for oxygen scavenging and their capacity of oxygen reactivity theoretical and experimental at 25oC without catalyst...... 73

Table 4-2: Conditions used for oxygen scavenging and their capacity of oxygen reactivity theoretical and experimental with catalyst (10mg) at 25oC ...... 76

Table 4-3: FTIR Peak locations of LA before and after oxidation ...... 77

Table 4-4: Apparent rate constant (k') day -1 obtained at 30oC and initial pressure of 20 psi...... 85

Table 4-5: Apparent rate constant of different systems (k'- day-1). Catalyst was a cobalt complex...... 85

Table 4-6: Apparent rate constant with dilution of Linoleic acid in hexanoic acid ...... 88

Table 5-1: Peak Location of functional group in PET and PET/LA systems ...... 97

Table 5-2: Peak location of functional groups for LA and solvent in extraction study. . 102

Table 5-3: Weight loss observed for physical blends for various loading of physicals blends. The weight loss was obtained at 250oC ...... 106

Table 5-4: Weight loss analysis of PET and PET/LA samples – pellets to bottles...... 109

Table 5-5: Transition temperature of PET and PET/LA systems...... 111 ix

Table 5-6: Density, mechanical properties and haze level of bottle side wall ...... 112

Table 5-7: Oxygen transport properties PET and PET/ LA bottle sidewall...... 113

Table 6-1: Peak Designation for Linoleic acid, base PET and PET/ LA reacted groups.

...... 121

Table 6-2: End group Concentration and TGA weight loss of PET and PET/LA of the blends. The amount of unbound LA was calculated based on the increase of carboxyl end group concentration and the TGA weight loss relates to the unbound LA present in these systems. All the samples used were in form of films...... 129

Table 6-3: End group Concentration and TGA weight loss of PET and PET/LA of reactive extruded samples. The bound amount of LA was determined based on the decrease in hydroxyl concentration using end group analysis of the films prepared. The

TGA shows the amount of unbound LA that was present, pellets were used in the TGA analysis...... 130

Table 6-4: Nomenclature for the Blend and Reactive extruded PET/LA systems...... 132

Table 6-5: Density and free volume of PET and PET/linoleic acid blends...... 135

Table 6-6: Density and free volume of PET and PET/LA reactive extruded films...... 136

Table 6-7: The thermal effect of adding linoleic acid as blends in PET as measured by

DSC...... 137

Table 6-8: The thermal effect of adding linoleic acid as reactive extruded pellets as measured by DSC...... 138

Table 6-9: Cooling rate required to obtain amorphous polymer...... 140

Table 6-10: Cooling rate required to obtain amorphous polymer...... 141

Table 6-11: Non isothermal crystallization studies to determine n and K, PET and

PET/LA blends...... 142

Table 6-12: Non isothermal crystallization studies to determine n and K, PET and

PET/LA reactive extruded...... 143

Table 6-13: Intrinsic Viscosity of PET and PET/LA blended films ...... 145

Table 6-14: Intrinsic Viscosity of PET and PET/LA reactive extruded pellets...... 146

Table 6-15: Orientation conditions and crystallinity level of blended films...... 151

Table 6-16: Oxygen Permeability values of PET and PET/LA blends and their Barrier improvement factor (BIF). The (BIF) is the permeability of oxygen for PET/LA compared to PET at same processing condition...... 152

Table 6-17: Orientation conditions and crystallinity level of reactive extruded films. .. 155

Table 6-18: Oxygen Permeability values of PET and PET terminated LA and their

Barrier improvement factor ...... 156

Table 6-19: Oxygen permeability’s and Barrier improvement factor (BIF) for PET with

0.5% nominal loading of LA ...... 159

Table A-1: Oxygen scavenger studied using linolenic acid (0.5 ml) at 25oC and an initial pressure of 20 psi ...... 195

Table A-2: Oxygen scavenger studied using linoleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi ...... 196

Table A-3: Oxygen scavenger studied using oleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi ...... 197

Table A-4: Oxygen scavenger studied using linolenic acid (0.5 ml) at 25oC and an initial pressure of 20 psi with cobalt as catalyst ...... 198

Table A-5: Oxygen scavenger studied using linoleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi with cobalt as catalyst ...... 200

Table A-6: Kinetics study of linoleic acid ( Figure 4-7) ...... 201

Table A-7: Kinetics study of linoleic acid diluted in heaxanic acid ( Figure 4-8 (a)) .... 202

Table A-8: Kinetics study of linoleic acid diluted in heaxanic acid ( Figure 4-8 (b)) .... 202

Table A-9: Kinetics study of linoleic acid diluted in heaxanic acid ( Figure 4-8 (c)) .... 203

Table A-10: Oxygen permeation studies on PET bottles...... 204

Table A-11: Oxygen permeation studies on PET 1sp bottles ...... 206

Table A-12: Oxygen permeation studies on PET 2sp bottles ...... 208

Table A-13: Oxygen permeation studies on PET SSE control amorphous film ...... 210

Table A-14 Oxygen permeation studies on PET +0.25 LA SSE amorphous film ...... 211

Table A-15: Oxygen permeation studies on PET +0.5 LA SSE amorphous film ...... 212

Table A-16: Oxygen permeation studies on PET +0.65 LA SSE amorphous film ...... 213

Table A-17: Oxygen permeation studies on PET +0.9 LA SSE amorphous film ...... 214

Table A-18: Oxygen permeation studies on PET SSE oriented film...... 215

Table A-19: Oxygen permeation studies on PET+ 0.25 LA SSE oriented film ...... 216

Table A-20: Oxygen permeation studies on PET+0.5 LA SSE oriented film ...... 217

Table A-21: Oxygen permeation studies on PET+0.65 LA SSE oriented film ...... 218

Table A-22: Oxygen permeation studies on PET+0.9 LA SSE oriented film ...... 219

Table A-23: Oxygen permeation studies on PET RE control amorphous film ...... 220

Table A-24: Oxygen permeation studies on PET+0.11 RE amorphous film ...... 221

Table A-25: Oxygen permeation studies on PET+0.33 RE amorphous film ...... 222

Table A-26: Oxygen permeation studies on PET RE control oriented film ...... 223

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Table A-27: Oxygen permeation studies on PET+0.11 RE oriented film ...... 224

Table A-28: Oxygen permeation studies on PET+0.33 RE oriented film ...... 225

xiii

List of Figures

Figure 1-1: Structure of Polyethylene terephthalate (PET)...... 2

Figure 1-2: Barrier properties of common packaging polymers [10] ...... 3

Figure 1-3: Various packaged Food and their required oxygen permeation level ...... 4

Figure 1-4: Schematic of approaches used to reduce oxygen transport in package sidewall

(a) Passive and (b) Active barrier system ...... 5

Figure 1-5: Structure of (a) Polybutadiene (b) Linoleic acid ...... 6

Figure 1-1-6: PET terminated with linoleic acid ...... 7

Figure 1-7: Selected Scavenger a) Oleic Acid b) Linoleic Acid c) Linolenic Acid ...... 8

Figure 2-1: Cumulative oxygen through polymer. (a) PET, (b) PET with passive barrier and (c) PET with active barrier ...... 13

Figure 2-2: Polymer coated with impermeable layer ...... 15

Figure 2-3: Diffusion of Gas through polymer with nano materials (a) shows the tortuous path (b) the path of direct diffusion...... 16

Figure 2-4: Nature in which clay is present with a polymer. The presentation has been taken from [58] ...... 17

Figure 2-5: Multilayer system ...... 19

Figure 2-6: Sachets with oxygen scavengers: Ageless® ...... 25

Figure 2-7: Structure of (a) Polybutadiene (b) Transesterification of PET and PB

(represented as R)...... 27

Figure 2-8: Structure of MXD6 ...... 30 xiv

Figure 2-9: An oxidation mechanism of nylon system. This representation has been taken from [103]...... 31

Figure 2-10: Oxygen permeance of a PET bottle wall with out and with MXD6. The metal catalyst concentration was varied and their effect is shown [106]...... 32

Figure 2-11: a) Monoolein b) 3-cyclohexene-1,1 dimethanol...... 34

Figure 2-12: Effect of rate on the oxygen transport through polymer with oxygen scavenger with the polymer. The Effect of various Thiele moduli has also been represented...... 37

Figure 2-13: Composition of the unsaturated fatty acid in common oil. This representation has been taken from http://www.canola-council.org/ ...... 39

Figure 2-14: Barrier Improvement Factor (BIF) for various systems found in literature. 42

Figure 3-1: (a) Oleic acid, (b) linoleic acid and (c) linolenic acid...... 45

Figure 3-2 Set-up used to determine the oxygen scavenger capacity...... 47

Figure 3-3: Set-up to monitor oxidation of LA ...... 48

Figure 3-4: Various processes used to prepare PET and PET/LA ...... 50

Figure 3-5: Schematic representations of twin screw extruder used prepare LA terminated

PET...... 51

Figure 3-6: Preform heating profile...... 53

Figure 3-7: Flow of PET/LA samples using different methods and their characterization.

...... 55

Figure 3-8: End group analysis setup for deuteriation...... 57

Figure 3-9: Schematics of extraction process of LA from PET/LA powder to monitor presence of LA in the solvent...... 58

Figure 3-10: Weight loss of PET with heating ramp of 5oC/min. This is a curve of un- dried PET ...... 60

Figure 3-11: DSC run of PET @ 10oC/min. (a) First heating ramp and (b) Second heating ramp...... 62

Figure 3-12: Cannon Ubbelohde type 1B viscometer. Used to monitor solution viscosity of PET and PET/LA @ 25oC ...... 65

Figure 3-13: Calibration of Melt viscosity to intrinsic viscosity. Determined for know IV samples at a frequency sweep of 10 rad/sec at 270oC...... 66

Figure 3-14: Oxygen permeation setup...... 69

Figure 4-1: Moles of oxygen consumed per mole of OS for the three OS at 25oC, without catalyst when 0.5ml of OS was introduced and an initial pressure of 20 psi. (a) Linoleic acid, (b) Linolenic acid and (c) Oleic acid...... 72

Figure 4-2: Moles of oxygen consumed as function of time (a) linoleic acid, (b) linolenic acid and (c) oleic acid at 25oC in the presence of 20,000 ppm of cobalt catalyst...... 75

Figure 4-3: FTIR spectra of LA (a) before and (b) after oxidation (35 days) at 25oC at an initial pressure of 20 psi...... 78

Figure 4-4: FTIR of linoleic acid product after oxidation where vacuum dried over 24 hrs.

The peak decrease over time...... 79

Figure 4-5: Change in color due to oxidation of linoleic acid at atmospheric pressure and room temperature. (a) Picture taken on day 0 (b) Picture taken on day 15 (c) Picture taken on day 29 ...... 80

Figure 4-6: FTIR Spectra of LA being oxidized over time in glass cell with oxygen at room temperature. The oxidation experiment was conducted over 30 days...... 81

xvi

Figure 4-7: Plot of -ln (CA/CAO) verses time to Determination of Rate constant for linoleic acid determined at 30oC using an initial pressure of 20 psi ...... 84

Figure 4-8: Kinetics of oxidation of Linoleic when diluted in hexanoic acid. The linoleic acid fraction was varied between (a) 75, (b) 25 and (c) 10 % by volume...... 87

Figure 5-1: Bottles prepared using single and two stage methods...... 93

Figure 5-2: (a) NMR spectra of linoleic acid with peaks at 11.18 ppm - carboxylic acid peak, 5.36ppm - C=C double bond, 2.78 - CH3 group of the fatty acid dissolved in chloroform-D. (b) NMR spectra of PET bottle sidewall dissolved in Chlorofrom –D /

Trifluroacetic acid (70/30). There is no presence of C=C bonds in peak around 5.4 ppm for PET...... 96

Figure 5-3: PET terminated LA Structure ...... 96

Figure 5-4: NMR spectra of (a) PET, (b) PET+ LA 2sp Bottle side wall (c) PET+ LA

1sp bottle sidewall dissolved in Chlorofrom –D / Trifluroacetic acid (70/30). The peaks at (1) for C=C double bond (2) for CH2 group which are due to the presence of LA...... 98

Figure 5-5: NMR spectra of (a) PET, (b) PET/LA 2 sp bottle sidewall (c) PET/LA 1sp bottle sidewall . The reaction between hydroxyl end of PET and the carboxylic acid of

LA is confirmed by the appearance of a peak at 4.03 ppm...... 99

The carboxyl end group as function of linoleic acid loading are indicated by for two stage process ( ) and single stage process ( )...... 101

xvii

Figure 5-7: FTIR curves (a) PET+ LA (1%) physical blend, (b) PET, (c) PET/ LA 2sp pellets, (d) PET/ LA 2sp preform and (e) PET/LA 1sp preform. There are two distinct region (1) 3000- 2800 methyl bending and (2) Carboxyl peak ...... 104

Figure 5-8: Weight loss curves of physically blended samples of PET+ LA, to determine the nature of the weight loss curve obtained when heated to 300oC at a rate of 5oC/min.

Physical blends of PET with varying % of LA (a) 0% (b) 0.5% (c) 1.5% (d) 2.5% and (e)

7%...... 105

Figure 5-9: TGA weight loss curves for PET/LA samples. (a) PET, (b) PET/LA 2sp bottle sidewall (c) PET/LA 2sp preform, (d) PET/LA 2sp pellets, (e) PET/LA 1sp preform, (f) PET/LA( 0.5%) Linoleic acid blends...... 106

Figure 5-10: Cumulative oxygen permeated through the bottle side wall (a) PET, (b)

PET/ LA 1sp (c) PET/ LA 2sp...... 114

Figure 6-1: Flow diagram for processing of PET/LA samples using single stage (Blended films) and two stage (Reactive extrusion) and their characterization studies that were conducted on each stage...... 118

Figure 6-2: NMR spectra of the single stage or blended films prepared (a) PET, (b)

0.25PET (c) 0.5PET (d) 1PET (e) 2PET. The regions around 5.4 ppm (arrow 1) and 2.8 ppm (arrow 2) are due to C=C bonds present in LA. PET does not show any peak in these regions there by confirming the presence of LA...... 122

Figure 6-3: NMR spectra of reactive extruded pellets prepared (a) PET, (b) 0.25PET (c)

0.5PET (d) 1PET (e) 2PET. The regions around 5.4 ppm and 2.06 are due to C=C bonds present in LA. PET does not show any peak in these regions there by confirming the presence of LA...... 123

xviii

Figure 6-4: Zoomed NMR spectra of single stage or blended films prepared (a) PET, (b)

0.25PET (c) 0.5PET (d) 1PET (e) 2PET and (f) PET/LA (Bottle side wall). This is to show that using a single screw extruder blends were obtained as there was no peak at

4.03 which is present in reacted samples...... 124

Figure 6-5: Zoomed NMR Spectra of reactive extruded pellets prepared (a) PET, (b)

0.25PET (c) 0.5PET (d) 1PET and (e) 2PET. The twin screw extruder has confirmed reaction between the end groups of COOH of LA and OH of PET. The increase in concentration of LA has shown an increase in peak intensity which confirm with higher loading higher reaction has taken place...... 125

Figure 6-6: End group analysis of linoleic acid in PET and PET/linoleic acid formed by single stage process...... 127

Figure 6-7: End group analysis of PET and PET/LA two stage or reactive extruded films.

...... 128

Figure 6-8: Effect of loading LA on crystallization of PET from melt - (a) PET 0.9 B, (b)

PET 0.65 B, (c) PET 0.5 B, (d) PET 0.25 B and (e) PET...... 140

Figure 6-9: Effect of loading LA on crystallization of PET from melt - (a) PET 2 RE, (b)

PET 1 RE, (c) PET 0.33 RE, (d) PET 0.11 RE and (e) PET...... 141

Figure 6-10: Melt viscosity curves of PET/LA blended films of (a) PET, (b) PET 0.25 B,

Figure 6-11: First heating ramp of DSC to determine the amorphous nature in PET film.

...... 148

xix

Figure 6-12: Cumulative amount of oxygen permeating through amorphous PET and

PET/LA films. (a) PET, (b) PET 0.25 B, (c) PET 0.5B, (d) PET 0.65 B and (e) PET 0.9 B

...... 149

Figure 6-13: First heating ramp of DSC to determine degree of crystallinity in oriented

PET film...... 150

Figure 6-14: Cumulative amount of oxygen permeating through oriented PET and

PET/LA films. (a) PET, (b) PET 0.25 B (c) PET 0.5 B (d) PET 0.65 B and (e) PET 0.9 B at 25oC...... 151

Figure 6-15: Cumulative amount of oxygen permeating through amorphous PET and PET terminated LA films. (a) PET, (b) PET 0.11 RE and (c) PET 0.33 RE ...... 154

Figure 6-16: Cumulative amount of oxygen permeating through oriented PET and PET terminated LA films. (a) PET, (b) PET 0.11 RE and (c) PET 0.33 RE ...... 155

Figure 6-17: NMR spectra of PET/LA systems after oxygen permeation. (a) PET, (b)

PET 1sp bottle side wall, (c) PET 2sp bottle, (d) PET 0.9B and (e) PET 0.33RE ...... 157

Figure 8-1: Oxygen Sorption Setup, to determined solubility coefficient of the polymer

...... 170

Figure 8-2: β- cryptoxanthin ...... 171

Figure 8-3: Lutein ...... 171

Figure 8-4: Linoleic acid mixed with oleic and hexaionic acid (10% Linoleic acid was present in the mixture) (a) Linoleic acid/ oleic acid (b) Linoleic acid/ hexaionic acid. 173

List of Abbreviations

OS Oxygen scavenger

LA Linoleic acid

OTR Oxygen transmission rate

P Permeability

D Diffusivity

S Solubility

Qt Cumulative amount of oxygen

MAP Modified atmospheric packaging

PET Polyethylene terephthalate

EG Ethylene glycol

TPA Terephthalic acid

DMT Dimethyl terephthalate

WVTR Water vapor transmission rate

PEN Polyethylene naphthalate

EVOH Ethylene vinyl alcohol

PB Polybutadiene

LA Linoleic acid

Tg Glass transition temperature

Tc Crystallization temperature

xxi

Tm Melt Temperature

DMA Dynamic mechanical Analysis

MXD6 m-xylenediamine

FTIR Fourier transform infrared

DSC Differential Scanning Calorimetric

FFV Factional Free Volume

CHDM 3-cyclohexene-1,1-dimethanol

1sp Single stage process

2sp Two stage process

TGA Thermal gravimetric analysis

IV Intrinsic viscosity

xxii

Chapter 1

1. Introduction

The plastic food container industry has a forecast of nearly 5% annual growth till

2017 and is expected to see an increase in the annual growth rate after 2017 [1]. The

demand for food packaging is on the rise globally, with developing countries consuming

more packaged food. This has driven the interest in improving the shelf-life of packaged

food, which is done by reducing the amount of oxygen that permeates through the

packaging [2]. Polyethylene terephthalate (PET), shown in Figure 1-1, is commonly used

for packaging and bottles. PET is a low-cost semicrystalline thermoplastic polyester

made by direct esterification of ethylene glycol (EG) with terephthalic acid (TPA) or

transesterification of dimethyl terephthalate (DMT) with EG. The clarity of PET gives

the container a visual appeal along with light weight and high strength. In the packaging

industry, one of the main markets for PET is plastic bottles for carbonated soft drinks,

water, and juice. While large amounts of PET resin are used for the production of stretch

blown bottles [3], the inherent oxygen barrier is not very high for PET which affect

potential markets.

Figure 1-1: Structure of Polyethylene terephthalate (PET).

Oxygen can decrease the shelf life of food products through color degradation, microbial spoilage, nutrient loss, as well as flavor and odor changes [4-7]. The shelf life of the food product is dependent upon the amount of oxygen that diffuses through the wall of the container along with the oxygen that is present in the headspace during packaging. It is desirable to reduce this diffusion to as small a value as possible. PET has a relatively good gas barrier property however this is not sufficient for long term storage applications of oxygen sensitive products (i.e. beer, tomato sauce) [8]. Figure 1-2 is a graphical representation of the barrier properties in terms of oxygen transport rate (OTR) with respect to oxygen and water vapor transmission rate (WVTR) for common packaging polymers. It is necessary to preserve water while packaging liquids as low WVTR’s are desirable. It is desired to have the oxygen permeation as low as possible towards the goals that are highlighted in Figure 1-2.

Foods can tolerate different levels of oxygen permeation, which impacts the selection of the polymer required to package that food product. The cost of the polymer also plays an important role as PET costs less than polyethylene naphthalate (PEN) or

ethylene vinyl alcohol (EVOH) which has an excellent oxygen barrier property. Oxygen permeation through EVOH films increases sharply when the relative humidity increases which limits its application. Figure 1-3 gives details about different foods that are packaged and the allowable amount of oxygen content, the figure also give details about the temperature range at which the food are packaged [8]. Figure 1-3 shows that PET can be used to package materials under C, D and E. It has to be noted that even the addition of small quantities of oxygen (1-5 ppm) that could come in contact with a packaged food can affect the shelf life period [9].

GOAL

Figure 1-2: Barrier properties of common packaging polymers [10]

A: Beer B: Wine, Processed meat products C: Pickles & Relish, pickled meat and fish D: Jams, Jellies, and Syrups E: Fruit Juice F: Toppings, Canned Fruits G: Catsup, Apple Sauce, Pasta Sauce, Tomato Juice H: Canned vegetables and meat products

atm) day. in mil/(100 CC

Figure 1-3: Various packaged Food and their required oxygen permeation level

Total removal of headspace oxygen and reduction of oxygen diffusion will prolong product shelf life by minimizing oxidation while maintaining the quality of oxygen sensitive food. The oxygen that is present above the packaged food has been successfully addressed through modified atmospheric packaging (MAP). In order to reduce diffusion through the package sidewall, the following two approaches have been used. (1) Passive methods involving the addition of nanomaterial like clay or glass fibers

[11] This addition would increase the tortuosity within the matrix which extends the diffusion path through the side wall, thereby reducing the permeability (Figure.1-4 (a)).

Small molecules are added into the polymer which has been known to reduce the 4

fractional free volume of the polymer and thereby reduce the oxygen permeability through the polymer. (2) Active method incorporates compounds within the polymer with functional groups that react with the oxygen diffusing through the sidewall. This oxygen scavenger reduces the amount of oxygen that would permeate through the sidewall until the scavenging capacity is reached. This approach has the advantage that the active scavenger can also react with the oxygen that is present within the packaging (Figure.1-

4(b)). However, a limitation of this method is that after the scavenger has been utilized no further reaction will take place and the permeability will return to that of the base polymer. Additionally the byproduct of oxidation must be determined, since they are used for food packaging and byproducts can the affect flavor of the packaged food [12-16].

(a) (b)

Figure 1-4: Schematic of approaches used to reduce oxygen transport in package sidewall

(a) Passive and (b) Active barrier system

Unsaturated hydrocarbons have been used commercially as active scavengers in which C=C provide sites for reaction with oxygen [13, 17, 18]. Polybutadiene (PB) shown in Figure 1-5 (a) is a commercially available oxygen scavenger that was copolymerized with PET via the dicarboxylic acids end groups. The addition of PB with

PET led to improved oxygen barrier properties [13]. Oxygen scavenging follows a free radical mechanism as explained in detail in Chapter 2. One drawback of this system is that after oxidation, chain scission occurs which can result in lower molecular weight and potential degradation of polymer properties [13, 19]. Other available commercial systems have been shown to reduce oxygen transport in PET like sachets which are placed within the packaged food, multilayer systems and copolymers. While these systems are promising, there is a need for an active scavenger with high reaction kinetics and capacity for oxygen to expand application of PET packaging. Unsaturated fatty acids with a combination of reactive end group and multiple double bonds are promising materials for oxygen scavenging as shown in Figure 1-5 (b). These fatty acids are consumed as part of our diet through various oil sources and taken as dietary supplement and are hence safe for use in packaging. Fatty acids have one functional end group which is a key challenge in incorporating this compound into the polymer. The fatty acids can be included within the polymer by blending or reaction to produced PET terminated with the fatty acid.

(a) (b)

Figure 1-5: Structure of (a) Polybutadiene (b) Linoleic acid

1.1 Hypothesis

Reactive extrusion will lead to PET terminated with the fatty acid a representation is shown in Figure 1-6. When fatty acids are introduced into PET, they would react with oxygen permeating through PET/fatty acid system to reduce permeability.

Figure 1-1-6: PET terminated with linoleic acid

1.2 Research Objectives

Active barriers in PET have been extensively explored [13, 14, 19] , however much work is needed to identify novel compounds that have rapid kinetics, can be incorporated with PET during processing and are relatively cost effective. There is interest using renewably sourced compounds as additives for polymer systems [20-23].

Unsaturated fatty acids were investigated as a potential oxygen scavenger system for PET in this project. Currently, fatty acids are used as food coating to prevent the oxidative degradation of food and in drying of paints [24]. Fatty acids can be obtained as value added products from the biofuel industry, however, fatty acid with unsaturated carbon bonds (C=C) that act as sites of oxidation are of specific interest. The impact of the number of unsaturated bonds on the capacity and rate of reaction with oxygen will be

explored for the three scavengers shown in Figure 1-7. The carboxyl end group will allow reaction with the hydroxyl end group of the PET to form a copolymer to improve the gas barrier property of PET. The primary goal is to determine impact of addition of model fatty acid on properties of PET for packaging.

Specific objectives were:

A. Analysis of effect of degree of unsaturation of fatty acid on oxygen reaction

kinetics and sorption capacity

The oxygen reaction kinetics and capacity were measured for three model

unsaturated fatty acids shown in Figure 1-7. These fatty acids were chosen

for this study because they have similar chemical structures with

increasing number of double bonds that acts as potential sites for

oxidation. The practical outcomes of this objective were selection of fatty

acid for further studies within PET.

(a) (b)

(c)

Figure 1-7: Selected Scavenger a) Oleic Acid b) Linoleic Acid c) Linolenic Acid

B. Analysis of the presence of model fatty acid and study of impact on the thermal

and mechanical properties of the PET/scavenger system.

The optimal fatty acid that is selected from objective (A) was used to

make a PET/scavenger system. Two approaches were taken to incorporate

the fatty acid with PET using (i) single screw extruder (blends) and (ii)

twin screw extruder (Reactive extrusion). The effects on the properties of

PET by the addition of model fatty acids using the two methods were

determined.

C. Analysis of the effect the PET/scavenger systems on oxygen transport.

When bottles are prepared they undergo an orientation process. Oxygen

permeation studies were conducted on amorphous and oriented films of

the blended and reactive extruded sample. This study was conducted to

determine the effect that orientation has on oxygen permeation when

model fatty acid were added.

Methods reported to affect oxygen transport given in literature have been described in detail in Chapter 2 along with mechanism of oxidation of an oxygen scavenger. The various methods that were used in this research have been described in detail in Chapter 3. Selection of an oxygen scavenger that could be introduced into a polymer based on the oxygen scavenger capacity and kinetics has been discussed in

Chapter 4. The proofs of concept were determined by preparing bottles and testing their oxygen permeability has been discussed in Chapter 5. The impact of loading linoleic acid as blends and reactive extruded films has been studied and discussed detail in Chapter 6.

New ideas that could be considered for future work have been described in Chapter 7.

Chapter 2

2 Literature Review

When materials are selected for packaging the permeability of oxygen is a key

parameter to consider. Glass or metal do not allow any gases to permeate, however

plastic packaging allows a low rate of oxygen permeation. Oxygen plays a role in food

spoilage as it would enable aerobic microorganisms which could follow an enzyme-

catalyzed reaction or oxidation of lipids and fats which causes food spoilage [25]. The

time over which food can be consumed and not cause any health issue (food poisoning),

and can be on the shelf of store is referred to as the shelf life. The amount of oxygen that

is present within packages is due to two factors (1) oxygen that is trapped during

packaging and (2) the oxygen that permeates through the polymer sidewall. The shelf life

of packaged food can be extended using different approaches, such as modified

atmospheric packaging (MAP), increasing thickness of the packaging film and reducing

the permeability of gas through the polymer. Modified atmospheric packaging

approaches for oxygen sensitive food uses flushing with inert gases to reduce the initial

oxygen concentration to less than 2% [25, 26]. This project will focus on reducing the

oxygen permeating through the polymer side walls through modification of polymer and

highlights the various techniques that have been used to reduce oxygen permeation. 10

2.1 Permeation

Permeability is a measure of the rate of gas transport through a polymer P

(cc/day.atm), film of thickness ‘l’ (m), P is the pressure and thickness normalized flux of a gas as shown in equation 2-1 [27].

(Flux) P = ∆p Eq 2-1 ( ⁄l)

Where Δp is the pressure difference across the film and the driving force of gas permeation. Gas permeability (P) occurs by solution diffusion process which is a combination of sorption into the polymer and diffusion across sidewalls.

P = D × S Eq 2-2

Where D is diffusivity, cm2/day and S solubility, cm3/ day. cm3

Solubility is the amount of gas that can be absorbed by the polymer and diffusivity is the amount of gas that passes through the polymer. Several factors affect the permeability including crystallinity and microstructure of the polymer, chain packing, excess free volume and chain segmental mobility. The polymer microstructure is affected by modification to the chain packing and mobility due to processing or introduction of additives [28]. While both diffusion and sorption can be modified to affect the permeability most methods to improve barrier properties target diffusion as described in 11

detail below. The free volume of the polymer is decreased by the inclusion of additives which fill free volume or attached to the backbone of the polymer which cause increased crystalline level which would affect the solubility of gas into the polymer. The effective diffusion path length of a gas through the polymer would be increased, thereby the diffusivity through the polymer would be decreased.

The oxygen transmission rate (OTR) is the measured amounts of oxygen that passes through a polymer film per unit area. Permeability can be calculated from the

OTR using the equation 2-3 [29], which is the ratio of oxygen transmission rate to the feed pressure. The permeability is the permeance time the thickness of the film.

cc OTR Permeance, ( ) = Eq 2-3 atm. day. 100in2 Pressure

cc. mil Permeability, ( ) = Permeance × thickness Eq 2-4 atm. day. 100in2

The cumulative amount of oxygen (Qt) that permeates through polymer over the course of the experiment determined from the oxygen transmission rate given by equation

2-5.

Eq 2-5 퐧

퐐퐭 = ∑ 퐎퐓퐑 × 퐓퐡퐢퐜퐤퐧퐞퐬퐬 × 퐭퐢퐦퐞 ퟏ

P - Permeability (a)

)

P (b)

Time Lag Time, days

Figure 2-1: Cumulative oxygen through polymer. (a) PET, (b) PET with passive barrier and (c) PET with active barrier

Typical plots of Qt as a function of time for different polymer systems are shown in

Figure 2-1. This figure shows three cases of Qt as a function of time (a) PET, (b) PET with a passive barrier and (c) PET with an active scavenger. When Qt as a function of time was plotted for PET, the region over which the OTR was constant the slope of Qt would give the permeability of the polymer. However, when a passive barrier is produced in the form of introducing nano materials, small molecule free volume additives or copolymers, there is a reduction in permeability of the polymer (Figure 2-1 (b)). Figure

2-1 (c), illustrates the effect of addition of an ideal active scavenger on the transport of the oxygen in polymer. There is an increase in time lag until the scavenger capacity was consumed by oxygen. After this point the permeability of polymer should theoretically be the same as the base polymer. When some oxygen scavengers were introduced no time 13

lag was observed, only a reduction in permeability this was due to low reaction rate of oxygen with the scavenger in the polymer.

2.2 Passive Oxygen Barrier

Passive barrier reduces the gas permeation rate through a film by broad physical methods where no reaction with oxygen takes place. Addition of a low oxygen permeable layer as a coating, films, and multilayer films would increase overall resistance to mass transfer and reduce the oxygen permeability of the polymer. Impermeable nanomaterial can be dispersed in the polymer to increase effective diffusion path length and decrease diffusivity. These methods are described in detail below.

2.2.1 Coating

In coating systems, the surfaces of PET containers are coated with a layer of organic or inorganic material which has high oxygen barrier properties. These systems require an adhesive layer to ensure defect free formation of coating as shown in Figure 2-

2. Some of the coating materials are diamond like carbon (DLC), hydrogenated amorphous carbon film, silicon oxide, aluminium, zinc oxide and silicon nitride [30-37].

This method has been shown to improve the oxygen barrier by 30 times compared to the base PET. The coating were achieved using a microwave plasma reactor [38], plasma enhanced chemical vapor deposition, vacuum deposition chemical evaporation and sputter deposition [30, 39]. The permeability of gases can be reduced by increasing the

thickness of the defect free coating layer. The drawbacks of this process are defects (1)

holes that are formed due to incomplete coating, pinholes and cracks are small in nature

but can allow gases to permeate through the films, (2) uneven thickness in the coated

layer make it difficult to obtain uniform layer and (3) some coating techniques require

that the surface of the polymer be modified for the coatings to be adhered to the surface.

Another drawback in this process is the cost of equipment and speed of production of

container becomes limited [40-44]. Recycling of these systems becomes a challenge as it

would be hard to remove the coating from the polymer.

Impermeable layer

Adhesive

Polymer Substrate

Figure 2-2: Polymer coated with impermeable layer

2.2.2 Nanocomposites

Dispersing impermeable nanomaterials including exfoliated nanoclay, silicates,

titanium oxides and talc within PET has been shown to reduce the oxygen permeability

[45-51]. The impermeable additives increase the tortuous path length through PET film

with a corresponding decrease in effective diffusivity as represented in Figure 2-3. The

addition of nanomaterial has been known to affect the crystallization temperature and

affect the rate of crystallization[52] as it acts a nucleating site. Since the path of diffusion

is longer the effective diffusivity of permeability of gas is reduced which reduces the

permeability of the polymer. The addition of nanocomposites also improves mechanical

strength, it affect the thermal properties of PET as well. Nano material have been used in

other polymers like high density polyethylene, polyethylene, Ethylene vinyl alcohol

(EVOH) and polyamide [53-57] where improvement in mechanical properties have been

noted along with reduction of oxygen permeation.

(b)

(a)

- Non reactive material

Figure 2-3: Diffusion of Gas through polymer with nano materials (a) shows the tortuous path (b) the path of direct diffusion.

The nanoclay can agglomerate within the polymer which is challenge for

application. Attempts to disperse the clay within a polymer can have three outcomes

shown in Figure 2-4 (1) Agglomeration where the clay particles are surrounded by

polymer (2) Intercalation – the spacing between the clay layers called d- spacing

increases from an initial value by the diffusion of polymer chains or its monomers into

the clays layer. When intercalated system is formed, the clay layers are parallel to each

other. (3) Exfoliated system when the individual layer are completely separated through

the polymer matrix. While inclusion of nanoclay within polymer leads to reduction on

permeability of gas, there are challenges of this method is achieving exfoliated systems.

Figure 2-4: Nature in which clay is present with a polymer. The presentation has been taken from [58]

The nature in which the nanomaterials are present within the polymer has been explained in detail for clay but is true for silicates as well. Exfoliation has been achieved by increasing the d-spacing of clay using ion exchange process [59], reducing the average particle side of the nanomaterial can achieve exfoliation [52]. The presence of these nanomaterials reduced oxygen permeability by 30 to 70% based on how they were incorporated and their distribution within the polymer as either intercalated or exfoliated systems.

2.2.3 Polymer Blends:

Blending a relatively high permeability polymer with a low permeability polymer in different fraction has been shown to reduce the overall permeability of the system. The most commonly used high barrier polymers are Ethylene-Vinyl Alcohol (EVOH) and polyamide [60-67]. The permeability of various polymer are given in Table 2-1. The drawbacks of this approach are the incompatibility of the polymers with PET which leads to phase segregation and poor mixing. Compatibilizers have been used to reduce this drawback.

Table 2-1: Oxygen permeability of various polymers [68]

Polymer Permeability of Oxygen

cc-mil/(100in2.day.atm)

Polyvinyl Alcohol (PVA) 0.01

Polyacrylonitrate (PAN) 0.04

Polyvinylidene Chloride (PVDC) 0.1

6,6,6 Nylon 1.5-2.5

Polyethylene terephthalate (PET) 5- 10

Ethylene-Vinyl Alcohol (EVOH) 0.006 (0% RH)

2.2.4 Multilayer Films

Multilayer films consist of a low permeability flayer that is sandwiched between traditional packaging polymers (PE, PET, PS, PA, PP) layers by co-extrusions processes

[16, 69-71]. The most commonly used barrier polymers are EVOH, polyamide and polybutadiene. The required number of layers and the thickness of each layer were determined based on the expected shelf live that was required for a given product. When the polymers used for multilayer are not compatible with each other hence an adhesive layer was used. Figure 2-5 shows a typical multilayer system. There have been studies where polymers with nanomaterial’s or graphene have been sandwiched between base polymer using the multilayer co-extrusion process [72-74]. A multilayer system could also have an oxygen reactive layer which react with the permeating oxygen [75]. There are difficulties in terms of recycling PET where separation of the low permeable layer becomes difficult [30-35].

Adhesive/Tie layer

Barrier polymer layer

Base polymer layer

Figure 2-5: Multilayer system

2.2.5 Additives that affect free volume

The free volume of polymers is defined as the volume not been occupied by the polymer and is related to the nature of the polymer chain packing [76]. Specifically there are two environments in glassy polymers in which transport can occur (i) densely packed regions and (ii) excess free volume which can increase the solubility of gases into the polymer and also effect the diffusion of gases through the polymer. Recent studies have explored the use of small molecules that act as anti-plasticizer in PET and reduce the diffusion of gasses. Where the excess free volume that is present in the polymer have been occupied by the small molecule. Some examples of antiplasticizers are dimethyl terephthalate (DMT), phenacetin, acetanilide, dimethyl naphthalate (DMN) and caffeine

[27, 77, 78]. Antipasticizaion is believed to be caused by a loss in free volume and subsequent suppression of chain motion [28]. Changes in the concentration of these molecules in the polymer can lead to plasticizing or anti-plasticizing effects.

Plasticization tends to swell polymer and leads to reduction in glass transition temperature (Tg), antiplasticization occurs at lower concentration. These anti-plasticizer can improve the crystallinity of the polymer and has an added effect that improve barrier properties through increase in diffusion path length [27, 77]. The reduction in oxygen permeation for these systems ranged from 16 to 66% based on the amount of antiplasticizer that was added into the polymer. When a reactive small molecule is added into polymer they could affect the free volume and affect the diffusivity of the polymer.

2.2.6 Crystallization and branching

Crystallinity plays an important role in the permeability, higher crystallinity leads to reduction in permeability of gases through a reduction in segmental motion, and local chain packing. PET has a characteristic property of high level of strain induced crystallization which improves oxygen barrier properties upon orientation. This is achieved during stretch – blow molding in packaging production, but there are limitations to the improvement that can be achieved as small crystals are formed.

Branched modification of PET can be achieved using co- reaction of bi, tri or tetra functional polyol to produce random side chain groups [79, 80]. Naphthalene dicarboxylic acid and succinic acid are few compounds that are used and the branched nature would increase crystallinity thereby reducing oxygen permeation.

2.2.7 Copolymers

PET has two functional end group in each of it monomers, ethylene glycol (EG) has two hydroxyl and terapthalic acid (TPA) has two carboxyl end. There are a large number of monomers with di-functional carboxyl and hydroxyl end group that can be copolymerized to improve barrier properties [81-88]. Monomers that have been used to produce copolyester include isophthalate, phthalate, 1-8 naphthalate, 1-5 naphthalate, 2-6 naphthalate, 1-8 anthracenate, 2-6 anthracenate, 2-7 pyrenate, 3,4-bibenzoate 4,4- bibenzoate, succicinic acid, glutaric acid adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and bis(2- hydroxyethyl)hydroquinones are a few to name. The copolymer were confirmed by NMR or FTIR, the properties of the polymer that were determined were glass transition (Tg), density, intrinsic viscosity and DMA study to 21

determine the effect on free volume by the addition of new monomers. The transport properties that were determined are permeability, diffusivity and sorption. Some of the copolymer that were prepared where oriented/ heat set and their oxygen permeability were determined as well. The reduction in oxygen permeability varied on the loading of the copolymer which have resulted in reduction of 0 to about 50%

2.3 Active Oxygen Barrier

Active barriers are additives which are introduced into packaging system to permanently bind oxygen and reduce the oxygen that interacts with packaged compound.

The purpose of an oxygen scavenger is to limit the amount of oxygen within the package that is available for reactions that lead to reduced functionality of the product. An oxygen scavenger material has a compound that can react with oxygen when incorporated within the package to effectively remove oxygen from the inner package environment [61]. This method when combined with MAP is the most effective for oxygen sensitive food [89] where MAP reduce the oxygen content within the package reducing the oxygen content to less than 1% and the oxygen scavenger in polymer react with the oxygen that permeates through the sidewall. There are many commercial scavenger systems that are presently being used [44].

There are number of commercially available oxygen scavengers on the market as shown in Table 2-2. These scavengers use different mechanisms to react with oxygen within the packaging systems. Iron has been blended into polymer where it can used to bind the oxygen. The list included polymer, enzymes, salts and formulations that can

react with oxygen. Mechanisms for commonly used systems are described in detail below.

Table 2-2: Commercial oxygen scavenger available in market.

Trade Name Type Principle / Active Substance

Oxygaurd Plastic trays Iron based

Amosorb Films, Bottles Polybutadiene/ Cobalt

Shelfplus O2 Films Iron based

Darex Bottles Ascorbate/sulphite

Zero2 Films Photosensitive/organic compound

Os 1000 Films Light activated scavenger

Oxbar Bottles Nylon/Cobalt

Bioka Sachet Enzyme Based

Hygard Bottles Salt (Sodium Borohydride)

Diamond Clear Bottles Formulation/ Metal

2.3.1 Sachets

The earliest oxygen scavenger system was Ageless® (Mitsubishi Gas Chemical

Co., Japan) which is an iron based scavenger system inside a sachet that is placed within the packaged as shown in Figure 2-6, a gram of iron can react with 300 cc of oxygen[89,

90]. Moisture activates the scavenging process and has to be maintained for the process to continue. ATCO® (Emco Packaging Systems, UK; Standa Industrie, France) and

Oxysorb® (Pillsbury Co., USA) are similar systems. The iron sachet systems were designed to reduce oxygen levels to less than 0.0 1% within the package [89, 90] . The mechanism of the iron based scavenger system is given below.

Fe → Fe2+ + 2e-

- - ½ O2 +H2O + 2e → 2OH

2+ - Fe +2OH → Fe(OH)2

Fe(OH)2 +1/4 O2 +1/2 H2O → Fe(OH)3

A major challenge with use of sachets is potential of direct placement within the packaged food. The sachet come with a label “Do not eat” this becomes a concern as there are chances of metal contamination.

Figure 2-6: Sachets with oxygen scavengers: Ageless®

This potential for food contamination have can be overcome if the oxygen scavenger are present within the polymer structure. Systems have been developed in which metal catalyst and oxygen reactants have been incorporated into the polymer to achieve a reduction in oxygen transmittance through a polymer.

Oxygen scavenger films are designed to have a positive effect on the product as they reduce the head space oxygen that was not removed by gas flushing and vacuum system and pulls out the entrapped and dissolved oxygen. This would result in improved flavor and color profile in highly oxygen sensitive products. Efforts with these oxygen scavenger systems are focused on producing transparent films to address the need of the consumers and producers.

2.3.2 Amosorb

BP Amoco developed Amosorb technology which utilizes hydroxyl terminated polybutadiene (PB) as an oxygen scavenger as shown in Figure 2-7 (a) [91]. A copolymer of the PET and PB was formed by a trans-esterification mechanism during reactive extrusion, a representation is shown in Figure 2-7 (b). The reactive extrusion was done at

260 to 270oC where PET was feed into the extruder at 8 pound/hr. and maintained a residence time of 4 min. The molecular weight of PB can vary from 100-10,000 and can be loaded in PET from 0.5 % to 12% by weight. The resulting films were stretched bixaillay using a stretch ratio of 2.5 x 4 and the thickness varied between 1 to 10 mil, the transparency of the films were above 70% for light of wavelength in the range of 400 to

800nm. PB was able to form olefin rich domains with PB of spherical diameter of 0.5 to

1 µm. The addition of PB has lowered the intrinsic viscosity (IV) of systems, when 4% low molecular PB was used the IV of the system was about 0.48 and when 8% high molecular PB was used the IV of the system was 0.5. The oxygen scavenging properties of copolymer with low molecular weight PB were at a faster rate when compared to the high molecular PB. The copolymer showed` a significant increase in rate of oxygen reaction when a metal catalyst (Cobalt acetate) was introduced [13]. Copolymers with capacity of 0.4cc of oxygen per gram of the scavenger have been reported [91-93] .

Much like the Oxbar system, the oxygen transmission rate is nearly zero until the scavenger is completely utilized. IR studies were conducted to determine the mechanism of oxidation and to perform end group analysis that confirmed reactive extrusion [14].

(a)

(b)

Figure 2-7: Structure of (a) Polybutadiene (b) Transesterification of PET and PB (represented as R).

The oxygen scavenging for PB follows a free radical mechanism [94-96] with three stages: (1) initiation (2) propagation and (3) termination. This has been established for pure PB.

Initiation:

This step occurs when a free radical donor including a metal catalyst/ peroxide was introduced into the system as a catalyst as shown in Equation 2-7. Heat or light can be used to initiate the process in some scavenger systems [13, 18, 96-98]. The unconjugated C=C reacts with oxygen in the presence of catalyst with the ability to form perxyl and alkoxyl free radicals. This reaction is shown in equation 2-6 to 2-8 which illustrate the binding of oxygen to form a radical. The initiation stage of the reaction occurs very fast, the free radicals are the end product of this step. The catalyst move from one energy state to another finally returning to its original state this was first studied on iron catalyst and then extend to other metals as well [98].

RH+ O2 ROOH Eq 2-6 ( Under heat/ light/ peroxide/ metal catalyst)

2+ * - 3+ ROOH+Co RO + OH +Co Eq 2-7

3+ * + 2+ ROOH+Co ROO + H +Co Eq 2-8

R - represents aliphatic componds

Propagation:

When the free radical collide with a PB segment, the C=C breaks and forms a new covalent bond, by accepting the free radical the propagation process continues there by resulting in more free radical. Propagation stage usually results in cross linking of polymer chains. The propagation stage can be represented by equations 2-9 and 2-10.

* * ROO + RH R’OO Eq 2-9

* * RO + RH R’O Eq 2-10

R’ represents a change to R either shorten or crosslinked

Termination:

Termination occurs when two free radical collide to form peroxyl crosslinks or peroxide that can reversibly decompose to form free radicals. The free radical has low stability and can from carbonyl group and main–chain scissions as a result of β scissions.

Alkoxyl, olefin and aldehydes can be formed due to scission type reaction. Aldehydes can be further oxidized into carboxylic acid, ester and ketones. Equation 2-11 and 2-12 show the termination step and equation 2-13 show the β scission to complete the reaction. 28

* * R’OO + R’OO ROOR + O2 Eq 2-11

* * RO + RO ROOR Eq 2-12

* RO + ½ O2 2C=O Eq 2-13

It has to be noted from the mechanism of oxidation of oxygen scavengers require a metal catalyst for the reaction with oxygen to take place. Various studies have shown that the reaction rate is affected by the amount of oxygen in the system, the recommended amount is between 50- 200 ppm of the catalyst. The addition of catalyst above 200 ppm does not result in improvement in the rate of oxidation [13]. The mechanism of oxidation has been confirmed using FTIR, NMR and XPS to determine the products of oxidation at various stages [13, 18, 99]. This work also confirmed that low molecular weight PB had higher rate of oxidation than higher molecular weight is accordance to other studies.

When copolymer of PET and PB were made by reactive extrusion process a trans

–esterification process takes place during reactive extrusion. This has been confirmed for reaction of low and high molecular weight hydroxyl terminated PB with carboxyl end group concentration of PET [13]. This shows that addition of PB resulted in decrease of carboxyl end group. These methods will be used to confirm inclusion of fatty acid within

PET.

2.3.3 Oxbar systems

The Oxbar system is a blend of extruded PET and an aromatic polyamide

(MXD6) that acts as the scavenger through reaction with amide. The structure of MXD6 is shown in Figure 2-8, the sites of oxidation are the methyl group close to the amine as indicated with an arrow that follows a free radical mechanism [100, 101]. An illustration of the polyamide free radical mechanism is given in Figure 2-9 which follows the free radical mechanism was discussed for polybuatdiene system. This system can behave as an oxygen scavenger when a metal catalyst is added but would behave as a passive barrier without a catalyst as MXD6 has a lower permeability than PET [102].

Figure 2-8: Structure of MXD6

Figure 2-9: An oxidation mechanism of nylon system. This representation has been taken from [103].

The amount of oxygen consumed by the scavenger depended on the amount of

MXD6/catalyst that was present within the polymer. The addition of MXD6/catalyst has been shown to reduce the oxygen transmission rate to nearly zero until scavenger capacity was reached [15]. Figure 2-10 shows oxygen permeance through a bottle wall

for this system and the importance of catalyst for oxygen to react with the MXD6. Note that there is no reaction without catalyst. The rate of oxygen transport is initially zero with 50 ppm of cobalt as catalyst but steadily increases after much of scavenger was utilized. At 200 ppm the reaction rate was high and no oxygen permeated for 300 days.

After all of MXD6 has been utilized as scavenger the polymer systems will exhibit increase in permeability similar to the non-reactive polymer [101].

This oxygen scavenger system can used as both a mono and multilayer system and is known to reduce the oxygen transmission rates to nearly zero until the scavenger is fully utilized. Monolayer film incorporated the MXD6 within PET through reaction with

PET to form copolymer. The scavenger system is very effective, however reaction with oxygen can lead to chain scission after the scavenging has taken place resulting in low molecular weight polymers as amide sites are attacked along the chain [104, 105].

Figure 2-10: Oxygen permeance of a PET bottle wall with out and with MXD6. The metal catalyst concentration was varied and their effect is shown [106].

The major drawbacks of using MXD6 system are incompatibility of with PET which causes opaqueness due to phase segregation [104, 105]. This can be overcome by reacting the polyester (PET) and polyamide (MXD6) to obtain a copolymer using catalyst which would enable an ester – amide interchange reaction [107]. However, this method can lead to formation of cross links and undesirable change in the melt rheology.

The most effective way to make MXD6 compatible with PET is to use small amount of sodium 5- sulfonated isophthalate [102] sodium p-toluene sulfonate [108] to facilitate the polyester – polyamide reaction. This reaction can follow two reaction mechanism (1) outer amide – inner carbonyl interchange reaction and (2) inner amide – inner carbonyl interchange reaction [107-109]. These reaction were confirmed using NMR and FTIR.

2.3.4 Other oxygen scavenger systems.

Monounsaturated diol 3-cyclohexene-1,1dimethanol (CHDM) and monoolein

(MO) (shown in Figure 2-12) which both have an oxidizable group were copolymerized in different molar ratio with TPA and EG to produce co polyester with branches shown in

Figure 2-11[14]. NMR was used to confirm that PET has a MO and CHDM bound to

PET structure. The work investigated the kinetics of oxidation of MO and CHDM. The addition of these oxygen scavengers can affect the rate of isothermal crystallization. The copolymers exhibited different glass transition, melting and crystallization temperatures than PET. The oxygen transmission rate of these copolymers was lower than PET[14].

This was attributed primarily to oxygen scavenging by CHDM and MO.

(a)

(b) Figure 2-11: a) Monoolein b) 3-cyclohexene-1,1 dimethanol.

Systems that are used as oxygen scavengers mostly have a metal catalyst present when copolymerized with PET undergo chain scission which reduces molecular weight.

However, monoolein and 3-cyclohexene-1,1dimethanol are branched structured so that molecular weight would not be affected by scavenging reaction.

When oxygen scavengers were used in the form of PB and MXD6, the reaction follows a free mechanism in presence of catalyst and the level of catalyst determined the effectiveness of the oxygen scavenger. For PB systems low molecular weight were shown to have better kinetics that a higher molecular weight PB. These systems demonstrate the potential of oxygen scavengers within polymers to reduce the oxygen transmission rate. However, there is considerable interest in developing scavenger systems with high capacity and rapid kinetics to further extend the operating range of packaging systems. To date unsaturated fatty acids have not been investigated in the literature as oxygen scavengers in polymers. However, these compounds exhibit oxygen scavenger potential and are used as antioxidants.

2.4 Rate of scavenging in polymers

2.4.1 Thiele modulus

An oxygen scavenger that is dispersed within the polymer can react with oxygen that is dissolved within the polymer film. Transport of oxygen through a film is a mass transfer process (diffusion) so that both the rate of reaction and diffusion determine the effectiveness of the scavenger. The Thiele modulus which relates the rate of reaction of oxygen scavenger to the rate of diffusion of the oxygen to the scavenger sites, can be calculated from equation 2-14. In the case of oxygen barrier system it would be preferred to have Thiele modulus ≥ 1 so that oxygen that diffuses to the scavenger sites reacts quickly. Therefore, fast rate of oxidation is preferred, the diffusion coefficient is a constant and thickness would vary based on the packing [110, 111].

2 k퐶퐵푂L Ф2 = ( ) Eq 2-14 D

Where

k – Reaction rate constant, cc/ (mol.sec-1)

CBO – Concentration of reactive compound, mol/cc

L – Thickness of film, m

D – Diffusion coefficient, m2/sec

The rate of reaction of the oxygen scavenger plays a vital in the behavior of an oxygen scavenger with the polymer. There are models which have been used to predict

the behavior of oxygen scavenger there were uniformly distributed throughout the polymer matrix like PET and PS [110, 112]. The authors analyzed the rate of oxygen entering a container as function of time for systems with increasing Thiele modulus.

Figure 2-12 shows oxygen permeation with increase Thiele modulus a presentation from

Dr. Cameron work on oxygen scavengers. The relative kinetics of the oxygen scavenger was the only parameter that was changed in these simulations. Based on the predictions of these models the importance of reaction rate in these oxygen scavenger systems has been emphasized. At low Thiele modulus the reaction was slow and there was a general decrease in permeability but little effect on the time lag. At increasing Thiele modulus the reaction rate increases and there is an increase in the time lag. Dr. Cameron model predict for an oxygen scavenger to behave like an ideal oxygen scavenger the Thiele modulus has to be greater than 10 [14, 112].

=0.1 =2 Slow =5

=15 Q

Fast

versus Time versus Oxygen Entering the Container theContainer Entering Oxygen

Figure 2-12: Effect of rate on the oxygen transport through polymer with oxygen scavenger with the polymer. The Effect of various Thiele moduli has also been represented.

2.4.2 Selection of renewably sourced scavenger

There is considerable interest in developing packaging materials from renewably sourced compounds [20-23], which has led to the development of novel polymers and additive systems [113, 114]. Oleic, linoleic and linolenic acids were chosen for this research. Linolenic acid is an omega 3 fatty acid, linoleic acid is an omega 6 fatty acid and oleic acid omega is a 9 fatty acid, which are taken as dietary supplements or as part of the diet [115] as they belong to essential fatty acid groups Figure 2-13 shows the percentage of different types of fatty acid in different oil. There is a high concentration of each fatty acid in these oils which will facilitate bulk application in packaging. 37

Linoleic and linolenic are auto-oxidizable compounds that would require little to no catalyst to initiate scavenging which is an advantage in proposed application. Energy input in the form of metals, light and temperature also promotes oxidation as they aid in the removal of hydrogen during initiation of oxidation [116].

The fatty acids have at least one C=C sites for oxygen scavenging via free radical mechanism as described in detail for the polybutadiene system. The reaction can form hydroperoxides which would decompose to form secondary oxidation products following a hemolytic process where oxygen – oxygen bond is cleaved which is followed by beta scission to form oxo compounds and unsaturated radical [116]. A cross-linked product which does not decompose may also be formed. Secondary product can include various types of aldehydes, carboxylic acid, alcohol and hydrocarbons. Based on the number of

C=C in the structure the rate of oxidation would be highest in linolenic acid which is followed by linoleic and oleic acid.

Oil, linoleic acid and oleic acid have been used in polymers as plasticizer where the glass transition temperature was reduced compared to the base polymer as well as, a reduction in the torque required to process the polymer [117-119]. These unsaturated fatty acid have been studied in rat for their oxidation properties [120] and the ester of these acids have been studied for their oxidation properties and the mechanism of oxidation[121].

Figure 2-13: Composition of the unsaturated fatty acid in common oil. This representation has been taken from http://www.canola-council.org/

2.5 Reactive Extrusion

As the selected oxygen scavenger have only one functional end group carboxyl end groups (-COOH) they can be attached to the end of the PET chain through a reactive extrude process. Reactive extrusion has been employed to prepare copolymers with different polymers, diols or diacid follows various reaction mechanisms which can broadly grouped into trans-esterification, alcoholysis and acidolysis [122-129]. This method has been extensively used when base polymer is being modified with small quantities of additives which were added to improve polymer parameters. Reactive extrusion has been achieved using a twin screw extruder. The reaction can be optimized

by varying the screw speed which affects the residence time of the polymer within the extruder. Low residence times have been shown to result incomplete reaction extrusion taking place, increasing the residence time leads to complete reaction. The temperature at which reactive extrusion were conducted also had an effect on the extent of reaction.

Reaction between the ends groups was confirmed by determining the end group concentration using NMR, IR or titration [68, 122, 128-134]. These methods will be used to monitor inclusion of LA within PET and reaction that may occur.

For the fatty acid the reactive process would lead to PET chain terminated with a fatty acid chain. The hydroxyl end group (-OH) of PET would react with the carboxyl end of the fatty acid that would follow a trans - esterification reaction process, this has been used in polybuatiene with two functional end group hence a copolymer was obtained.

2.6 Barrier Improvement Factor (BIF)

Unsaturated fatty acids have been introduction in polymers as plasticizers but they have not been investigated as oxygen scavenger in polymers [118]. The unsaturated fatty acid must be tested for the amount of oxygen scavenging capacity and confirm the mechanism in Chapter 4. The kinetics of oxidation has to be determined nature of oxygen reaction with the fatty acid and transport mechanism within the polymer. The unsaturated fatty acid can be introduced into PET as a blend or copolymer using reactive extrusion. Reactive extrusion would result in a PET end being terminated with 40

unsaturated fatty acid. The effect fatty acid would have on PET can be determined from thermal transition (Tg, Tc, Tm), density, mechanical properties and oxygen permeation.

The amount of fatty acid that is present has to determine along with the nature in which they are present has been confirmed using TGA, NMR end group and extraction.

The reduction of oxygen permeability can be represented as “Barrier

Improvement Factor”, which is the ratio of oxygen permeability of unmodified PET to modified PET for a given processing history given in equation 2-14. This would give the improvement achieved by addition of fatty acid and the influence of processing methods.

The BIF that were achieved by various systems are compiled in Figure 2-14.

푃푒푟푚푒푎푏푖푙푖푡푦푃퐸푇 퐵퐼퐹 = 푃푒푟푚푒푎푏푖푙푖푡푦 푃퐸푇/퐿퐴 Eq 2-15

The data in Figure 2-15 is for amorphous PET systems. The BIF copolymers range from

0.6 to 2.5, with maximum improvement for copolymers with improved chain packing.

Addition of nanomaterial’s and small molecule additives leads to a sharp reduction in permeability with BIF up to 4. The oxygen scavenger mentioned are CHDM and MO discussed in 2.3.4. Blends are mixing low permeable polymer like polyamide which have a BIF up to 2. Note that LA can affect transport as oxygen scavengers and a small molecule additive.

4.5

3.5

composites composites

)

S Nano

2.5

Free Free volume BIF PET 2

(P Copolymer 1.5

1 Blends 0.5 Oxygen Scavengers

Figure 2-14: Barrier Improvement Factor (BIF) for various systems found in literature.

Chapter 3

3. Materials and Methods

The literature has shown that various approaches have been used to prepare PET/

additives as copolymer or blends and processes that been followed in the research [135].

The various materials that have been used and the methods used to obtain PET/ LA

systems and different characterization techniques of the PET/LA have been explained in

this chapter.

3.1 Materials

Commercial PET (Array 9921) with intrinsic viscosity (IV) of 0.78 to 0.8 was

obtained from DAK America’s for this study. This is a copolymer that contains

cyclohexane dimethanol (CHDM) at undisclosed composition within PET. This is

consistent with lower density of Array 9921 film than pure PET. NMR has also the

confirmed presence of CHDM.

Three unsaturated fatty acids were investigated in this research. Oleic, linoleic

and linolenic acid were purchased from Sigma Aldrich, Atlanta, GA. The fatty acids were

chosen as they have the same number of carbon in its structure but various level of

unsaturation from one to three unsaturated double bonds. These fatty acid have similar 43

molecular weight with boiling points from 195 to 230oC and densities around 0.9 g/cc as shown in Table 3-1. The structures of the fatty acid are shown in Figure 3-1. These fatty acids were selected as potential scavenger because the unsaturation present in their structure could react with oxygen. The selection of the most suitable oxygen scavenger to be incorporated within PET was based on the oxygen scavenger capacity studies discussed in Chapter 4.

The presence of oxygen scavenger in the PET sample, was determined using

NMR with trifluroacetic acid-D and chloroform-D were purchased from Cambridge

Laboratories, Andover, MA and used to dissolve PET and PET/fatty acid samples.

Chloroform-D was also used for extraction of fatty acid from PET as it does not dissolve

PET. A density gradient column was made with water and calcium nitrate tetrahydrate

(Crystalline/Certified ACS), Fisher Scientific, Fair Lawn, NJ. End group of PET and

PET/fatty acid were determined following a deuteriation method where deuterium oxide was purchased from Sigma Aldrich, Atlanta, GA. Gasses used in this research, were oxygen and nitrogen (both industrial grade) for oxygen sorption test. The oxygen permeation study used oxygen and carrier gas a mixture of nitrogen/hydrogen (98/2) that was purchased from Airgas, Toledo.

Table 3-1: Properties of the scavenger

Scavenger Oleic acid [136] Linoleic acid [137] Linolenic acid [138]

Formula C18H34O2 C18H32O2 C18H30O2

Molecular 284.46 g mol−1 280.44 g mol−1 278.43 g mol−1

weight

Melting Point 13oC -5oC -5oC

Boiling point 195oC 230oC 230oC

Relative 0.887 g/mL 0.902 g/mL 0.914 g/ml

density

(a)

(b)

(c)

Figure 3-1: (a) Oleic acid, (b) linoleic acid and (c) linolenic acid.

3.2 Methods

3.2.1 Oxygen scavenging

The selection of an oxygen scavenger played a vital role in this research, as the performance of the scavenger before being incorporation into the polymer was determined. The key parameters of the oxygen scavenger were the isothermal capacity and kinetics of oxygen scavenging.

3.2.1.1 High pressure setup

The oxygen scavenging capacity of a material can be determined by conducting an oxygen reaction test in a pressured vessel as shown in Figure 3-2 at 25oC, where a known quantity of the reactive material and oxygen gas were introduced into the sorption cell at room temperature. The reduction in pressure was monitored as a function of time and the number of moles of gas were calculated using ideal gas law [139].

Figure 3-2 Set-up used to determine the oxygen scavenger capacity.

Based on the oxygen scavenger capacity and utilization of oxygen scavenger, linoleic acid was chosen as the most suitable oxygen scavenger that could be incorporated within PET. The decrease in oxygen pressure was monitored over initial time intervals to determine the kinetics of the oxygen scavenger using the same setup at

30oC. The initial rate was fitted to a pseudo first order model considering the period up to the first 48 hrs.

3.2.1.2 Low pressure setup

The hypothesis that the C=C bonds were consumed during the reaction with oxygen was confirmed using low pressure glass sorption system as shown in Figure 3-3.

In this setup pure oxygen was bubbled through viscous LA. The flow rate of oxygen was

20cc/min, this was run over 30 days, samples were collected every 2 days and the FTIR spectra were run on these samples.

Figure 3-3: Set-up to monitor oxidation of LA

3.2.2 Preparation of PET/LA systems

Linoleic acid was incorporated into PET using different processing methods

(blends and PET terminated with LA) Figure 3-4, shows the various processing methods.

Figure 3-4 outlines broad methods to produce samples for further analysis as either films or bottles. Specifically, (1) Single stage bottles – a mixture of LA and PET resin where introduced in the hopper of the injection molding machine to produce preforms. The preforms are blown into bottles in blow molding. (2) Two stage bottles – a mixture of LA to PET resin was introduced into twin screw extruder to form pellets ( PET is terminated

LA and some LA is blended). These pellets are used in injection molding to produce preforms. (3) Single stage films – a mixture of LA and PET resin are blended in a single stage extruder to directly produce films. (4) Two stage films – a mixture of LA and PET were added into twin screw extruders to produce pellets. The pellets are used in the single screw extruder to produce films.

Being application oriented bottles were prepared using two approaches, (1) PET terminated fatty acid and (2) PET/fatty acid blended bottles. The effect of blends and reactive process were also studied by preparing films blends where end group reactions did not took place and a case where reaction occurred. The impact of the addition of linoleic acid into the matrix of PET was investigated for the thermal, physical and oxygen barrier properties of PET in the films and blow bottles.

PET+ Scavenger

Reactive extrusion Injection Blown into Pellets molded Bottles (Twin screw extruder)

PET+ Scavenger Film

Blends Amorphous Films (Single screw extruder) Oriented

Figure 3-4: Various processes used to prepare PET and PET/LA

3.2.2.1 Blends of PET/ LA films

PET pellets were vacuum dried for 12 hrs at 110oC before mixing with an appropriate amount of linoleic acid and introduced into a single screw extruder with one heating zone to obtain sheets. Sheets were prepared with nominal loading of LA from

0.25 to 2 (%wt). The extruder was operated at 270oC (single heating stage) and the flat sheet die was maintained at 270oC, the extruder had a screw speed of 100 rpm. Films were prepared by pulling through a flat roller.

3.2.2.2 Preparation of LA terminated PET pellets

PET/LA mixture was introduced into a ZSK-30 conjugate co-rotating twin screw extruder with two circular die openings to obtain copolymer pellets of PET/LA as illustrated in Figure 3-5. All the heating zones of the extruder were maintained at 270oC and a screw speed of 100 rpm was used. The strands that were produced were quenched in water, and chopped into pellets. LA was loaded into PET at varying nominal weight ratio of 0.25 to 2 weight %. Nominal loading is defined as the feed composition of LA into hopper. The pellets that were prepared were later made into films or bottles depending on end use.

Dry PET

+ Chopper to Scavenger make Pellets (0.5%

Scaven

ger by

weightFigure 3-5: Schematic representations of twin screw extruder used prepare LA terminated PET. )

3.2.3 Preparation of Bottle

Two liter bottles were produced from the base PET and PET/LA, using both a (i) single stage and (ii) two stage process as described in detail below. Prior to processing,

PET pellets were vacuum dried for 12 hrs at 110oC, and physically mixed with the linoleic acid (LA). As shown in Figure 3-4, PET/ LA mixture was introduced into (a) twin screw extruder or (b) injection molding machine. Based on the initial introduction

PET/LA mixture the bottles were called a two stage or single stage process.

3.2.3.1 Injection molding

For single stage process, the mixture was introduced into ALLROUNDER 320s

Arburg Injection Molding Machine with 55-ton capacity, reciprocating-screw and a

SELOGICA control system to prepare a preform of PET and PET/LA. There are five heating zones and a nozzle heater, the heating zones were set at 270oC, 270oC, 280oC,

280oC, 280oC, 280oC from the hopper to the nozzle. The preforms were made into bottles and samples produced using this method will be referred to as PET/LA 1sp.

The two stage process, the PET/LA pellets that were prepared using the twin screw extruder (0.5 weight %) were vacuum dried followed by injection molding to produce the preform using the same conditions as the single stage process, the preforms were later made into bottles and sample produced using this methods will be referred to as PET/LA 2sp.

3.2.3.2 Stretch Blow Molding

The preforms were stretched and blown into bottles using a lab-scale stretch-blow molding machine which is equipped with a Sidel type heater box. The preform had heating profile divided into 12 regions as shown in Figure 3-6. The preforms were heated using infrared heating elements which were focused to soften the preforms prior to blowning into bottles. The heating elements were controlled by adjusting the heater voltage settings as shown in Table 3-2. The heater box speed was dialed to a value of 220 and the mandral speed was dialed to a value of 350 and the blow pressure was 300 psi.

1 2 3 4 5 6 7 8 9 10 11 12 = 3

Figure 3-6: Preform heating profile.

Table 3-2: Blow molding heaters voltage outputs.

Heater zone Voltage set (V)

1 235

2 235

3 235

4 210

5 145

6 120

7 170

8 170

9 180

10 180

11 180

12 180

3.2.4 Orientation of samples

Films prepared with LA were in the form of blends or PET terminated LA were amorphous in nature. A biaxial stretcher (LET) was used to obtain 30% crystallinity for each of the sample to mimic conditions in bottle. At 90oC and a stretch ratio of 2.5 x 2.5 orientation was achieved for PET and PET/LA films to achieve a crystallinity of 30%.

All processing equipment’s were housed in the Polymer Institute at the University of Toledo. The analytical methods used to characterize structure and properties following each processing method are show in boxes following each stage in Figure 3-7.

NMR, extraction and TGA were used to determine the presence of LA .End group was used to quantify the amount of LA that was present and confirm the nature in which it was present (i.e. Blend vs reaction). DSC was used to understand the effect of LA on the thermal properties of PET. The effect on the apparent molecular weight of PET following the addition of LA was determined by analysis of intrinsic viscosity. The oxygen transport through PET and PET/LA systems were determined using oxygen permeation studies.

Reactive extrusion Characterizion Pellets Injection Blown into NMR, IR , End group analysis, molded Bottles (Twin screw density and extruder) Permeation Characterization Characterization NMR, DSC , TGA, NMR, DSC , TGA , Extraction and Melt IV Extraction amd PET+ (Pellets) Melt IV Scavenger (preform)

Blends Characterization: DSC , Films NMR, TGA , Extraction (Single screw , End group analysis, extruder) density and Permeation

Figure 3-7: Flow of PET/LA samples using different methods and their characterization.

3.2.5 Characterization Methods

3.2.5.1 Fourier Transform Infrared Spectroscopy

FTIR was conducted using Varian FTIR spectroscopy enabled with a Varian resolution pro software. LA was analyzed before and after oxidation to understand the oxidation process of LA and the extent of reaction by following the peak for C=C which decreased as the reaction proceeded.

3.2.5.1.1 End Group Analysis

End group analysis was used to determine the end group concentration of PET and PET/LA films. If PET/LA systems were blended an increase in carboxyl group was expected and reaction occurred between PET and LA end group a decrease in hydroxyl end group of PET was expected with no change in carboxyl. Therefore, end group analysis could be used to determine if LA was simply blended within PET or if reaction extrusion take place. End group analysis was performed using deuteriation method [13,

140], the samples were placed in deuterium oxide at 50oC under an inert environment for

12 hours as shown in Figure 3-8. FTIR was also used to determine the end group concentration of both PET and PET/LA films in scan range of 4000 to 700 cm-1. End group analysis was conducted by subtracting the FTIR scan of dry films from the scan of deuteriated film. The subtracted spectra was fitted to a Gaussian curve, the area under the curve yielded the number of COOH end groups and OH end group using a previously established calibration [141].

Nitrogen

Water bath at 50oC Deuterium oxide Sample films Thermometer

Stirrer bar Heater plate

Figure 3-8: End group analysis setup for deuteriation.

3.2.5.2 NMR

The presences of LA within PET and nature of inclusion (ie. blends and reaction) can be analyzed using a solution NMR technique [17]. PET and PET/LA systems were dissolved in was chloroform- D/ trifluroacetic acid-D in volume ratio

(70/30) [142]. A Bucker Avance 600 was used to determine the proton NMR. The NMR curves were conducted on samples of PET with and without LA to confirm the presence of LA in the system. The reaction between hydroxyl end of PET and carboxyl end of LA

can result in a new peak which was used to monitor the reaction. This is consistent with

methods used for reactive extrusion in PET.

3.2.5.3 Extraction

Solvent extraction was commonly used to verify the presence of leachable

compounds in polymers [143, 144]. If LA was present as blend with PET, LA would

extract out of PET into the solvent. However, if the LA had reacted with the polymer end

group it cannot be extracted. PET/LA samples were powdered under liquid nitrogen to

avoid thermal degradation of the polymer and provide high surface area for extraction.

The powdered samples were incubated in Chloroform D solvent and the solvent were

analyzed using FTIR to determine the presence of LA, an illustration of the process is

given in Figure 3-9.

Powdered Sample

Solvent

Figu re 3-9: Schematics of extraction process of LA from PET/LA powder to monitor presence of LA in the solvent.

3.2.5.4 Thermal Analysis

Thermal analysis was performed to determine the effect of LA on thermal stability, transition temperatures and effect of cooling.

3.3.5.4.1 Thermal Gravimetric Analysis (TGA)

Thermal gravimetric analysis (TGA) was used to investigate the thermal stability of PET and PET/LA system [145, 146] and to confirm whether the linoleic acid was present in the polymer in a bound or unbound form. TGA analysis was conducted using a

TA Q50 TGA instrument at a heating ramp of 5oC/min under nitrogen atmosphere. The weight loss was measured as a function of temperature till 300oC (mp of PET 250oC). At a heating rate was 5oC/min which is slow enough to release any unbound LA as shown in

Figure 3-10. This model curve for un-dried PET where a weight loss upto100oC can be attributed to account for moisture in the sample, thus all sample were dried before TGA was conducted to be consistent. The LA has a boiling point of 230oC so that a maximum temperature 300oC was used.

100 99.9 99.8

99.7

99.6 99.5 99.4 Loss Weight % 99.3 99.2 99.1 0 100 200 300 400 Temperature, oC

Figure 3-10: Weight loss of PET with heating ramp of 5oC/min. This is a curve of un- dried PET

3.3.5.4.2 Differential Scanning Calorimetry (DSC)

DSC was used to determine the thermal transition temperatures. The DSC analysis was conducted on dry PET and PET/LA samples to understand the effect of the incorporation of LA had on the thermal properties of the polymer. A Perkin-Elmer DSC-

7 which is equipped with Priys software for data analysis was used. The glass transition, crystallization and melting temperatures were determined from the second heating ramp

@10oC/min [147-150]. The program used was

1. Heat from 40oC to 300oC at 10oC/min

2. Hold at 300oC for 5 min

3. Cool to 40oC at 300oC/min

4. Hold at 40oC for 5 mins 60

5. Heat from 40oC to 300oC at 10oC/min

A representation of DSC curve ( Figure 3-11) that shows step 1 and step 5 which are the heating ramps which information about thermal transition are determined. The first heating ramp is used to erase thermal history when the sample is dried at 110oC. The second heating ramp gives information about glass transition (Tg), crystallization (Tc) and melting (Tm) temperatures of PET and PET/LA samples. The first and second heating ramp the locations of the thermal transition are marked in Figure 3-11. The amount of crystallinity in films was determined from the first heating ramp. Note that there is no crystalline peak in the first heating ramp which indicates it is crystalline.

(a)

Melting temperature (Tm)

(b) Glass transition temperature (Tg)

Crystallization temperature (Tc)

Figure 3-11: DSC run of PET @ 10oC/min. (a) First heating ramp and (b) Second heating ramp.

Dynamic cooling studies were conducted to explore the effect linoleic acid had the on rate of crystallization of PET. For these studies, samples were melted and cooled at different cooling rates from 10oC/min to 40oC/min. This was done to determine the cooling rate required to obtained a completely amorphous polymer that could be used to determine the kinetics of crystallization [151, 152]. This is important for determining processing conditions needed for either amorphous or crystalline samples.

The program used for dynamic crystallization studies was

1. Heat from 40oC to 300oC at 10oC/min

2. Hold at 300oC for 5 min

3. Cool to 40oC at ramps from 10 to 40oC/min

The kinetics of crystallization established using dynamic cooling method mentioned above [153] , effect on the kinetics of crystallization due to linoleic acid on the were also determined. Crystallinity was calculated using the equation 3-1.

H푚 − H푐 퐶푟푦푠푡푎푙푙푖푛푖푡푦 (훸푐) = Eq 3-1 H표

Where Ho – is maximum heat absorbed by 100% crystalline for pure PET was 140 J/g

[154-156]. Hm and Hc are enthalpy of melting and enthalpy of crystallization.

The level of crystallinity present in each of the films/ bottle sidewall was determined from the first heating ramp and equation 3-1.

3.2.5.5 Intrinsic Viscosity (IV)

The intrinsic viscosity (IV) can be related to molecular weight of a polymer using

Mark-Houwink equation as shown in equation 3-2.

IV = k(Mw)a Eq 3-2

Where k and a are constant which can be obtained from the literature. The values of

The addition of small molecules into PET can have an impact on the flow of PET hence,

Melt IV method would not represent the IV of blends so solution IV method was employed. 63

3.3.5.5.1 Solution IV

Solution IV measurement follow ASTM D 4603-03 using a Cannon Ubbelohde type 1B viscometer as shown in Figure 3-12. The viscosity was determined at 25oC by placing the viscometer in a water bath. PET and PET/LA systems were dissolved in a

Phenol/ 1,1,2,2 tetrachloroethane (60/40 weight %) [150, 157-159] to obtain a solution concentration of 0.5 g/cc solution. The solution was heated to 110oC for 10 mins and cooled to 25oC. In order to determine the intrinsic viscosity of a polymer, viscosity at various concentration have to prepared and extrapolated to zero concentration which gives the intrinsic viscosity (IV) of the sample. This can also be determined by using a one point determination method for PET using the Billmeyer relationship as give in equation 3-3 [157].

0.25(ηr − 1 + 3 ln ηr) η in = ⁄C Eq 3-3

Where

ηin =Intrinsic viscosity

ηr = Relative viscosity

C = Concentration of the polymer solution (g/cc).

Figure 3-12: Cannon Ubbelohde type 1B viscometer. Used to monitor solution viscosity of PET and PET/LA @ 25oC

3.3.5.5.2 Melt IV

Melt viscosity approach was also used to determine the equivalent intrinsic viscosity (IV) of PET and PET/LA systems, using parallel plate Rheometric Scientific

(RDA III) dynamic analyzer at 270oC and a strain rate of 15% under nitrogen atmosphere

(avoid oxidative degradation). The parallel plates had a diameter of 25 mm, a frequency sweep of 10 rad/sec and the gap between the plates 1 mm and a frequency range between

1 to 500 rad/sec were recorded. This process was used to obtain an IV through a simplified process which does not involve any solvents. The zero- shear viscosity is independent of shear rate and this is obtained from the flow curves. Viscosity at 10 rad/sec is representative of zero shear viscosity. The parallel plate rheometer was calibrated with known IV of PET as shown in equation 3-4 and Figure 3 -13 shows the calibration cure that was used.

IV = m ln (η) + c Eq 3-4

Where m=0.388, c = -0.356

The IVs obtained from these methods were apparent IV of the systems. The IVs obtained from these two methods were compared as function of LA content and processing methods.

1.2

0.8

0.6

0.4 Intrinsic viscosity (dl/g) Intrinsic(dl/g) viscosity 0.2

0 2.00 2.20 2.40 2.60 2.80 3.00 3.20

Log(Melt viscoity at 10 rad/ sec)

Figure 3-13: Calibration of Melt viscosity to intrinsic viscosity. Determined for know IV samples at a frequency sweep of 10 rad/sec at 270oC.

3.2.5.6 Density

Density of the PET and PET/LA films were measured using a density gradient column filled with water-calcium nitrate solution maintained at 25oC using a water bath.

Small pieces of the samples were dropped into the density gradient column and the density of the sample was determined based on the calibration beads within the following

ASTM D 792-98. Based on the height of the sample in the column, the density of the sample can be determined from equation 3-5.

g Density ( ) = x(height) + y Eq 3-5 cc

Where x = -0.0018 y = 1.353

The density of the sample can be related to the effect of LA on fractional free volume

(FFV) of the sample. The FFV can be calculated from density and specific free volume using a group a contribution methods described by Van Krevelen [160].

3.2.5.7 Oxygen Permeation

The oxygen transmission rate is the rate of oxygen gas passing through a film or sheet per unit time. A Mocon test setup was used which utilizes a coulometric sensor to determine the oxygen permeation through PET and PET/LA films [161-165]. ASTM

D3985 was followed temperature at a temperature of 25oC and moist gases. Figure 3-14

shows an illustration of the permeation setup. In this setup, a carrier gas and oxygen is swept across film surface. The oxygen concentration in the permeate has measured using coulometric method. The cumulative amount of oxygen permeated through a film was calculated using equation 3-6.

OTR Q = ∑ t Thickness Eq 3-6 n

The OTR was determined from signal output and instrumentation factor of the device as shown in equation 3-7.

푂푇푅 = 푠푖푔푛푎푙 푥 퐼푛푠푡푟푢푚푒푛푡 푓푎푐푡표푟 Eq 3-7

The permeability was determined from OTR by knowing the partial pressure across the film and thickness of the films. The unit of permeability is cc (STP) mil/100 in2 day atm.

The Barrier improvement factor (BIF) is defined as the ratio of permeability of PET to the Permeability of modified PET as in equation 3-8 [38, 135, 166].

Permeability BIF = PET PermeabilityModified PET Eq 3-8

To the coulometric sensor

Carrier Gas N2/ H2 Mix Oxygen Film

Figure 3-14: Oxygen permeation setup.

Chapter 4

4. Oxygen scavenging capacity and kinetics

The oxygen scavenger embedded within a polymer can react with oxygen that

permeates through the polymer film. The ability of the scavenger to react with oxygen

can be determined before introduction into PET. For this project unsaturated fatty acids

were characterized for oxygen capacity and kinetics using described in method in 3.2.1.

The oxidation process follows a free radical mechanism as discussed in chapter 2. This

chapter discusses the screening of unsaturated fatty acids which could be introduced into

PET based on oxygen scavenger capacity and kinetics of oxidation.

4.1. Oxygen scavenger capacity

Three unsaturated fatty acids were chosen for this study with different levels of

unsaturation and the same number of carbon chain length were used as potential oxygen

scavengers (OS). Specifically oleic, linoleic and linolenic acids were chosen as they have

similar structure but the number of C=C bonds increases from 1 to 3. The oxygen

scavenger capacity was determined for the three fatty acids at room temperature (25oC).

In addition, catalyst was used to enhance the rate of reaction with oxygen [13, 14, 18, 99] to confirm auto catalyst by each fatty acid. The mechanism of the oxidation is given in equation 4-1and 4-2 and was described in section 2.3.2 for polybutadiene.

∗ + 푅퐻 + 푂2 → 푅푂푂 + 퐻 Eq 4-1

∗ − 푅퐻 + 푂2 → 푅푂 + 푂퐻 Eq 4-2

The oxygen scavenger studies were conducted using 0.5 ml of the oxygen scavenger and pure oxygen fills the volume above the oxygen scavenger with an initial pressure of 20 psi. The amount of oxygen that can react with a mole of each scavenger can be estimated assuming that one mole of oxygen reacts with one mole of C=C as shown in the mechanism. For linoleic acid at 25oC, the required pressure to completely react with the entire available C=C molecules is 23 psi. This is based on the assumption of ideal gas and two moles of C=C bonds for each of LA. Linolenic acid has three moles of C=C bonds per mole of linolenic acid, oleic acid has one mole of C=C bonds per mole of oleic acid.

2.5

2 (a)

1.5 (b)

Absorbed/ Inital Molesacidfattyof

2 0.5

0 0 5 10 15 20 25 30 35 40 Time, Days

The moles of oxygen absorbed by the three oxygen scavengers at 25oC and with no catalyst are presented in Figure 4-1, with time on the x axis and the ratio of moles of oxygen absorbed to the initial moles of the oxygen scavenger in the system on y axis.

Based on the assumption that each mole C=C can react with one mole of oxygen, this plot would give information about the reaction and the utilization of OS that were studied. From Figure 4-1 it can noted that linoleic acid and linolenic acid had much high rates of reaction with oxygen and oleic acid had a very slow rate of reaction with oxygen.

This which is consistent with literature that linoleic and linolenic acid were antioxidant that could react with oxygen without the use of any catalyst [116]. The reactive capacities of these fatty acids were determined when the pressure drop did not change as function of 72

time (̴ less than 5% change over 48 hrs). The scavenger utilization was calculated using a ratio of experimental and theoretical capacity as shown in equation 4-3.

푉표푙푢푚푒 표푓 표푥푦푔푒푛 푐표푛푠푢푚푒푑 퐸푥푝푒푟𝑖푚푒푛푡푎푙 푆푐푎푣푒푛푔푒푟 푈푡푖푙푖푧푎푡푖표푛 = Eq 4-3 푉표푙푢푚푒 표푓 표푥푦푔푒푛 푐표푛푠푢푚푒푑 푇ℎ푒표푟푒푡𝑖푐푎푙

The volume of oxygen reacted per gram of scavenger at the experimental conditions and their theoretical capacity were determined as shown in Table 4-1. Note that there was plateau for sorption of oxygen with linoleic and linolenic acid in Figure 4-1 indicating capacity was reached. The oleic acid did not reach a plateau so reported oxygen consumed is not the equilibrium capacity at more than 35 days.

Table 4-1: Conditions used for oxygen scavenging and their capacity of oxygen reactivity theoretical and experimental at 25oC without catalyst.

Initial Theoretical Experimental Volume of pressure Volume of Volume of Scavenger scavenger of Oxygen oxygen oxygen Utilization (ml) (psi) consumed* consumed*# 10 Oleic acid 0.5 20 80.5 0.12 (±3)

153 Linoleic acid 0.5 20 161 0.95 (±5)

Linolenic 122 0.5 20 244.5 0.50 acid (±5)

* cc of oxygen/ gram of scavenger

# the experimental average was based on three run of the experiment conducted.

The theoretical capacity was determined by using ideal gas law at STP and simple mass balance.

푛푅푇 Eq 4-4 푉 = ∆푃

The volume of oxygen that can react with the volume of fatty acid added to sorption cell can be determined by the number of moles of C=C bonds that were present (n

=0.003216) moles and standard pressure at STP taken as ∆푃, and the temperature was

25oC, as the experiment was conducted at this temperature. The theoretical capacity for linoleic acid with 0.5 ml loading there were 3.2 x 103 moles of double bonds leading to a theoretical capacity 161 cm3/ g of LA. The experimental capacity was determined from the difference in initial and final moles of the oxygen present in the sorption cell.

The conclusion from the oxygen scavenger study without catalyst is that oleic acid exhibits little reaction with oxygen as it was only able to use 10% of its oxygen reaction capacity. While linoleic and linolenic acids react with oxygen these fatty acids have different utilization of scavenging capacity. Linoleic acid and linolenic acid utilized

95% and 50% of their oxygen scavenging capacity respectively without a catalyst. This is indicative of autocatalytic anility the linoleic acid and linolenic aid.

The impact of catalyst (cobalt acetate) on oxygen scavenging capacity and reaction kinetics were determined for the unsaturated fatty acids. This addition had an significant impact on the oxygen scavenging capacity for oleic acid but in case of linoleic

and linolenic acid there was little effect of sorption capacity as shown in Figure 4-2 and the values are listed in Table 4 -2. For this experiment 10 mg of cobalt was added to the oxygen scavenging cell which is about 20,000 ppm which is in excess of the recommended amount of 300 to 500 ppm of catalyst. The purpose of the experiment was to determine if catalyst would facilitate the reaction of oxygen with the fatty acids. The oxygen uptakes by the fatty acid are shown in Figure 4-2, with the experimental and scavenger utilization are shown in Table 4-2. Oleic acid exhibited rapid reaction with oxygen in the presence of cobalt catalyst.

(a) 1.8 1.6

1.4 (b) 1.2 (c) 1

0.8 Absorbed/ Molesofacid fatty

2 2 0.6 0.4

MolesO 0.2 0 0 5 10 15 20 25 30 35 40 Time, Days Figure 4-2: Moles of oxygen consumed as function of time (a) linoleic acid, (b) linolenic acid and (c) oleic acid at 25oC in the presence of 20,000 ppm of cobalt catalyst.

Table 4-2: Conditions used for oxygen scavenging and their capacity of oxygen reactivity theoretical and experimental with catalyst (10mg) at 25oC

Initial Theoretical Experimental Volume of pressure Volume of Volume of Scavenger scavenger of oxygen oxygen Utilization (ml) Oxygen consumed* consumed* # (psi) 70 Oleic acid 0.5 20 80.5 0.87 (±2)

Linoleic 144 0.5 20 161 0.90 acid (±5)

Linolenic 128 0.5 20 244.5 0.52 acid (±1)

* cc of oxygen/ gram of scavenger

# the experimental average was based on three run of the experiment conducted.

Table 4-1 and 4-2 shows a comparison of scavenger the capacity and the scavenger utilization at equilibrium for the base fatty acid with and without the cobalt catalyst. In both cases, linoleic acid had over 0.9 scavenger utilization which is the best capacity out of the three fatty acids. The cost of the fatty acids was included in the selection of linoleic acid as potential oxygen scavenger. The ability of the oxygen scavenger to react was determined using these sorption studies and the conditions under which the reaction takes place were proposed. However, understanding the mechanism and the products that were formed is of interest for application in polymer. FTIR analysis of scavenger with time of exposure to oxygen was used to monitor the reaction

mechanism. This follows the free radical process for oxidation were unsaturated carbon bonds reacts with oxygen, the mechanism is explained in detail for polybutadiene in

Chapter 2 [13, 18, 99].

Table 4-3: FTIR Peak locations of LA before and after oxidation

Functional group Peak location (cm-1) CH2 3000-2880 CH 3010 CO 1710 OH 3500 ROOR 1230 C-O of C-O-O 970 C-O of O=C-O 1180

The peak locations for the base fatty acids and expected reaction products are shown in Table 4-3. FTIR was used to confirm the mechanism of oxidation where the

C=C bond which has a peak at 3010 cm-1 disappeared and new peaks at 1230 cm-1 appeared which corresponds to peroxides that are being formed as product of oxidation.

The FTIR spectrums for before and after oxidation are shown in Figure 4-3 for linoleic acid. In Figure 4-3, the complete disappearance of peak at 3010 is consistent with near complete utilization of double bonds for LA during scavenging. The FTIR spectra for linolenic, linoleic and oleic acid before oxidation were the same as each has the same functional groups and FTIR is not sensitive enough to distinguish the concentration of double bonds. Similar changes in peak were observed for each fatty acid.

FTIR shows a peak at 1710 which represent the carboxylic acid peak and the

-1 methyl group (CH3) are peaks at 3000- 2800 and 1400 cm . The key location to monitor

the reaction progress are represented as arrow 1 (C=C) and arrow 2 (ROOR), where peak

for C=C decreases and peak appears for ROOR are being formed.

(1) (2)

(b)

(a)

4300 3800 3300 2800 2300 1800 1300 800 Wavenumber cm-1

Figure 4-3: FTIR spectra of LA (a) before and (b) after oxidation (35 days) at 25oC at an initial pressure of 20 psi.

It was difficult to determine which peroxides were being formed by FTIR but the

general trend confirms that a free radical mechanism was followed [116]. The free radical

mechanism leads to water as a byproduct which is represented by a peak 3500 cm-1 for

the hydroxyl group in Figure 4-3 (b), this peak upon vacuum drying at 80oC over 24 hr

disappears over a 24 hour period as shown in Figure 4-4. This confirms that water is

being formed as a byproduct, the other products that was formed are peroxides which are

hard to differentiate.

Dried in the vacuum at 80oC

Linoleic acid after oxidation

2hr 24hr 3hr

Figure 4-4: FTIR of linoleic acid product after oxidation where vacuum dried over 24 hrs. The peak decrease over time.

4.2. Confirmation of the mechanism of oxidation

(1)

For the capacity studies, the oxidation was conducted in a high pressure cell and

hence physical changes in LA with time could not be noted. Oxidation studies of LA

were also conducted in a low pressure set up as described in Chapter 3 where LA samples

were taken at regular time intervals for FTIR analysis. Note that this experiment was

conducted at atmospheric pressure and room temperature (25oC) so that the kinetics

would be different than those in high pressure sorption cell. As the experiment proceeded

a change in color was observed that is consistent with oxidation which is shown in Figure

4-5. FTIR spectrum shown in Figure 4-6 indicated that there is a decrease in C=C peak

3010 cm-1 over time. As the reaction proceed the complex peak at 1220 cm-1 which

represent ROOR that was being formed. Peaks at 1000 and 1180 cm-1 represent C-O

functional group present in C-O-O and O=C-O group that are formed during the

intermediate steps of the free radical process as described in Chapter 2. Additionally,

there is a large peak at 3500 that is consistent with the pressure systems where water was

formed. These FTIR are consistent with the mechanism described for polybutadiene

oxidation.

(b) (a) (c)

Figure 4-5: Change in color due to oxidation of linoleic acid at atmospheric pressure and room temperature. (a) Picture taken on day 0 (b) Picture taken on day 15 (c) Picture taken on day 29

2935 cm-1

3010 cm-1 -1 3500 cm-1 1230 cm 1180 cm-1 980 cm-1

Day 29

Day 15

Day 7

Day 0 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber , cm-1

Figure 4-6: FTIR Spectra of LA being oxidized over time in glass cell with oxygen at room temperature. The oxidation experiment was conducted over 30 days.

4.3. Kinetics of Oxidation

There is an interest in determining reaction kinetics for oxygen scavengers that are incorporated within the polymer. Therefore, the rate of reaction for oxygen scavenging systems was determined by measuring the change in overall pressure in the steel cell over time, assuming there is an excess of C=C a pseudo first order reaction was assumed. In this study based on the oxygen scavenger capacity the kinetics were

determined from the pressure drop of oxygen and its concentration was determined using equation 4-5

훥푛 훥푃 퐶표푛푐푒푛푡푟푎푡푖표푛 ( ) = ( ) Eq 4-5 푉 푅푇

Where

Δn - Change in moles of oxygen due to reaction with scavenger

ΔP – Change in pressure

R – Gas Constant (82.05 cm3 atm K−1 mol−1)

T – Temperature the experiment was conducted (30oC)

V- Volume of fatty acid used (ml).

The pressure drop of oxygen was monitored as function time to determine the rate kinetics. The change in pressure drop of oxygen can be related to the change in the number of moles of oxygen.

The reaction could be stiochoimetrically written as

푂푥푦푔푒푛 (퐴) + 퐷표푢푏푙푒 푏표푛푑푠 표푓 퐿퐴 (퐵) → 푃푟표푑푢푐푡(퐶) Eq 4-6

Two moles of oxygen would react with one mole of linoleic acid as there are two unsaturated C=C present in linoleic acid. Moles of LA were determined from weight

(0.45 g) of LA used and its molecular weight (280g/mol). Weight of LA can be determined from volume (0.5 ml) used and density (0.901g/cc).

The rate equation based on equation 4-6 is given as equation 4-8

푑퐶퐴 −푟 = = 푘퐶 퐶 Eq 4-7 퐴 푑푡 퐴 퐵

Where CA – concentration of oxygen and CB – concentration of double bonds.

At 20 Psi gauge pressure the concentration of oxygen is 9.5x10-5 mol/cc (volume filled oxygen - 49.5 cc) and the LA concentration was 0.0032 mol/cc (volume 0.5 cc) . The concentration of LA is 32 times higher than of oxygen, and hence a pseudo first order form of the rate equation can be written as shown in equation 4-8 which on integration yields equation 4-9. For the study initial rate were determined for 0-2 days.

푑퐶퐴 −푟 = = 푘′퐶 Eq 4-8 퐴 푑푡 퐴

퐶퐴 −푙푛 ( ) = 푘′푡 Eq 4-9 퐶퐴푂

Where CAO - initial moles of oxygen. k’ - kCBO

0.45 0.4

0.35

) 0.3

AO 0.25

/C A

0.2 ln(C - 0.15 0.1 0.05 0 0 0.5 1 1.5 2 2.5 Time, Day

Figure 4-7: Plot of -ln (CA/CAO) verses time to Determination of Rate constant for linoleic acid determined at 30oC using an initial pressure of 20 psi

Figure 4-7 validates the assumption of pseudo first order rate mechanism. The apparent rate constant was the slope when –ln( CA/CAO) was plotted as function of time and shown in Figure 4-7. The average apparent rate constant was 0.2 day-1 when taken was over the first two day period which is also consistent with free radical mechanism which is of the first order [13, 18, 99]. The apparent rate constants for the three fatty acids were determined and are shown in Table 4-4.

Table 4-4: Apparent rate constant (k') day -1 obtained at 30oC and initial pressure of 20 psi.

Oxygen scavengers Without catalyst With Catalyst

Oleic acid -NA- 0.06

Linoleic acid 0.20 0.40

Linolenic acid 0.30 0.45

The apparent rate constants when compared to other oxygen scavenger systems were kinetics of oxidation were determined using different techniques from the one described in this work, but all of which followed a pseudo first order model are shown in

Table 4-5. The kinetics of linoleic acid was slightly lower than linolenic acid but when catalyst was added they were nearly similar to each other. When compared to monooolein (one C=C) the kinetics of LA were much faster but low molecular weight polybutadiene shows high rate than LA. The rate constant of LA was similar to high molecular weight polybutadiene, thus LA can be considered a suitable oxygen scavenger based on scavenger studies.

Table 4-5: Apparent rate constant of different systems (k'- day-1). Catalyst was a cobalt complex.

Oxygen scavengers Without catalyst With Catalyst

Oleic acid -NA- 0.06

Linoleic acid 0.20 0.40

Linolenic acid 0.30 0.45

Monoolein 0.062 (50oC) [14]

CHDM 0.033 (50oC) [14]

Polybutadiene (Mn:2800 0.5 (55oC) [13] g/mol)

Polybutadiene (Mn:1200 2.9 (55oC) [13] g/mol)

4.4. Kinetics under diluted conditions.

Linoleic acid would not have the same kinetics when diluted in a polymer and may echibits much less autocatalytic effect. Therefore oxygen scavenging studies were done in the high pressure setup was used, hexanoic acid as a non-reactive diluent for linoleic acid. The total volume of the mixture was maintained at 0.5 ml while the concentration of linoleic acid was varied between 10 to 75% and the initial pressure of oxygen was held at 20 psi. The diluted system also followed pseudo first order reaction model. Using the kinetic equation 4-9, for the diluted system the kinetic curves are shown in Figure 4-8 when the percentage of linoleic acid was 75, 25 and 10% by volume. The reduction in oxygen pressure was due to the presence of LA in the systems. Hexanoic acid by itself did not show any reduction of pressure.

0.25

0.2

(a)

0.15

)

A ln(C - 0.1

(b) 0.05

Figure 4-8: Kinetics of oxidation of Linoleic when diluted in hexanoic acid. The linoleic acid fraction was varied between (a) 75, (b) 25 and (c) 10 % by volume.

Dilution of linoleic acid showed a reduction in value of the apparent rate constant. Table

4-6 gives the apparent rate constant as a function of concentration of LA. The apparent rate constants decrease sharply with increase in dilution.

Table 4-6: Apparent rate constant with dilution of Linoleic acid in hexanoic acid

Linoleic acid faction Concentration Apparent rate constant

(% by volume) (mol/cc) (day-1)

10 0.00032 0.008

25 0.0008 0.0314

75 0.0024 0.11

100 0.0032 0.2

4.5. Calculation of Thiele modulus

When oxygen scavengers for polymer systems are being selected the kinetics of oxidation is parameter that is required to determine if the oxygen scavenger would behave as an ideally. Dr. Cameron’s work reported in PET Consortium (University of

Toledo) analyzed effect of Thiele modulus varied between 0 to 15 on the cumulative oxygen transport through a polymer film. Kinetics of oxidation and diffusion coefficient were important parameters to be determined. Thiele modulus defined as the ratio between reaction and mass transfer as shown in equation 4-10.

푘′ 푥 퐿2 Ф2 = Eq 4-10 퐷

Where k’ – Apparent rate constant

L – Thickness of the films (m)

D – Diffusivity of oxygen through PET

From literature the diffusivity of oxygen through amorphous PET is 4.8 x 10-13 m2/sec

[81, 86]

For the case of LA with no catalyst, the Thiele modulus for inclusion into PET bottle can be estimated The parameters used to estimate Thiele modulus are listed below. k = 0.2 day-1

L = 0.00025 m (assuming the this of the bottle side wall are 10 mil thick)

D = 4.8 x 10-13 m2/sec

From Equation 4-10

0.2 ( ) 푥 0.000252 Ф2 = 86400 = 0.3 4.8 × 10−13

훷 = 0.55

The Thiele modulus shows that if LA were to be introduced into PET it would behave as slowly reacting oxygen scavenger and would not show a time lag (period over which the oxygen transmission rate is zero) as shown in Figure 2-12. The net result would result in a slight shift in time lag and a decrease in permeability. The Thiele modulus that was obtained for this system was much higher than that of monoolein and CHDM systems

[14].

4.6. Conclusion

Three unsaturated fatty acids were chosen as potential oxygen scavenger for PET in this study, oleic, linoleic and linolenic acids. The reactivity of oleic, linoleic acid and linolenic acids with oxygen were studied at 25oC in pressure decay cell, using 0.5 ml of

OS and an initial pressure of 20 psi without a catalyst, Linoleic and linolenic acids reacted with oxygen but the reaction of oleic acid with oxygen under the conditions that are mentioned above was much lower. Linoleic acid utilizes most of it oxygen scavenging capacity, while linolenic acid utilizes only about 50% of its oxygen scavenging capacity. The oxygen scavenging capacity of these OS under the same condition mentioned above in the presence of cobalt acetate was used catalyst, the improvement in the scavenging capacity was marked when oleic acid was a scavenger showing 90% of scavenger utilization. However in the case of linoleic and linolenic acid the improvement in the scavenger utilization in the presence of catalyst was not appreciable. Thus LA as it reacted with oxygen and almost completely utilized the C=C even in the absence of catalyst was chosen for introduction into PET.

Since the oxygen scavenger capacities were done in a high pressure system, the changes in structure of the OS scavenger were not determined, hence a low pressure system was used to collect sample at different times. The oxidation process followed a free radical mechanism which has been verified by FTIR spectra where hydroxyl peak were formed and the C=C peak decreased over time, peaks due to peroxide where also noted. This is consistent with other scavenger with unsaturated groups.

The kinetics was determined using high pressure setup, during the initial time period the rate of reaction followed a pseudo first order reaction model. The kinetics was determined at 30oC and an initial pressure of 20 psi. The kinetics of oleic, linoleic and linolenic acid with and without catalyst were determined and compared with the other oxygen scavengers. The Thiele modulus which was used to determine if reaction with oxygen or oxygen diffusion through PET had a dominating effect was determined, the

Thiele modulus of 0.55 was obtained which indicated that the systems would be slowly reacting system.

Chapter 5

5 Bottles Blown with PET/ LA

Linoleic acid was chosen as the model scavenger to prepare bottles and films with

PET as it had the best oxygen scavenging capacity and kinetics as discussed in Chapter 4.

As this work is application oriented and geared toward the packaging industry, two liter

bottles were prepared with PET/LA to establish the effectiveness of the oxygen scavenger

on reducing oxygen permeability. The impacts of LA on processing ability of the

mixture, thermal-mechanical and oxygen transport properties of the bottle sidewalls were

monitored.

The bottles were produced using two methods that involved introducing the LA

either in an extruder to form compounded pellets or the injection molding step to form

preform. Specifically, the single stage process involves direct mixing of the 0.5 wt% LA

with PET pellets feed into hopper of the injection molding machine to produce preforms.

In the two stage process, a twin screw extruder was used to produced pellets of 0.5 wt%

LA in PET that were introduced into the injection molding machine to produce the

preforms. The preforms were blown into two liter bottles for testing in both cases.

Controls with base PET were produced using a two stage process without addition of LA.

Images of the bottles that were produced using both methods are shown in Figure 5-1. 92

ddition of LA did not cause any haze but there was a slight yellow coloring to the bottle produced by the two stage process.

The effect of processing method on blending and extent of reaction of LA with

PET end group to form PET terminated LA was characterized using NMR, end group analysis, thermal gravimetric analysis and solvent extraction will be discussed in section

5.1. The impact of inclusion of LA on the thermal-mechanical properties of the bottle sidewall will be discussed in section 5.2. Finally, the oxygen permeation through samples cut from sidewall with LA produced using the single and two stage methods will be compared with the control PET in Section 5.2.3

PET PET 0.5% 0.5% PET 1 Stage 2 Stage process process

Figure 5-1: Bottles prepared using single and two stage methods

5.1 Presence of LA within PET

5.1.1 Solution NMR of Bottle Sidewall

Solution NMR was used to confirm the presence of LA within the PET following each stage of processing from pellets to preform and bottle sidewall. In addition, H-

NMR was used to confirm reaction between carboxyl end group of LA and the hydroxyl end group of PET. The H-NMR spectra of LA and the base PET are shown in Figure. 5-

2 with peak designations for each structure listed in Table 5-1. Of specific interest for this work are the peaks for LA at 5.4 ppm for the C=C bonds, at 2.8 ppm for the methyl peak, and 11.18 ppm for the carboxylic acid end group. The base PET has a peak at 8.13 ppm which is representative of protons present in the terephthalic acid ring and at 4.78 ppm for protons of ethylene glycol bound in chain the of the polymer. Reaction between carboxyl end group of the LA and hydroxyl end of the PET is expected to result in a shift in the peak at 4.03 ppm for the ethylene glycol end groups. The proposed structure PET terminated LA is shown in Figure 5-3.

The presence of LA within PET was confirmed using solution H-NMR of the bottle sidewalls. The peaks at 2.8 ppm (Arrow at 2) and 5.4 ppm (Arrow at 1) in the spectra for the bottle sidewall shown in Figure 5-4 are consistent with the presence of

LA. The NMR spectra for the samples produced using the single stage and two stage methods are similar and indicate that LA was incorporated within the samples when

using both methods. This data does not address whether or not the LA reacted with the

PET to form a PET end capped LA. The carboxylic acid end groups of LA were masked by the presence of the more abundant TFA solvent used to dissolve the PET. Therefore data for the carboxyl end group of LA could not be used to confirm reaction with hydroxyl group of PET.

The reaction between the hydroxyl end group and carboxylic acid were confirmed by the presence of a peak at 4.03 ppm as shown in Figure 5-5. This peak is due to shift in

CH2 of ethylene glycol adjacent to the hydroxyl end group to form an ester in the PET terminated LA. The H-NMR results are consistent with inclusion of the LA within the

PET and binding of the LA to polymer end group. Because the peaks were small and difficult to accurately quantify for this relative low level of LA within the system, the extent of reaction between the carboxyl group of LA and the PET hydroxyl end group was confirmed and quantified using end group analysis.

1.0 PET.002.001.1r.esp

0.9

0.8

0.7

0.6

0.5

0.4

0.3 Normalized Intensity

0.2

0.1 (a) 0

-0.1 (b)

11 10 9 8 7 6 5 4 3 2 1 0 Chemical Shift (ppm)

Figure 5-3: PET terminated LA Structure

Table 5-1: Peak Location of functional group in PET and PET/LA systems

Peak Location

(ppm)

CH3 0.90

CH2 in chain 1.33

CH2 ( second group from – 1.65

COOH end)

CH2 before and after C=C 2.06

CH2 (near –COOH) 2.36

CH2 ( between C=C bonds) 2.8

CH (C=C) 5.4

PET Ethylene Glycol in chain 4.78

Benzene ring 8.13

PET-LA PET-COO-LA 4.03

PET Control.001.001.1r.esp

0.010

(1) (2) 0.005

(c)

-0.005 (b) Normalized Intensity

-0.010

(a) -0.015

8 7 6 5 4 3 2 1 0 Chemical Shift (ppm) Figure 5-4: NMR spectra of (a) PET, (b) PET+ LA 2sp Bottle side wall (c) PET+ LA 1sp bottle sidewall dissolved in Chlorofrom –D / Trifluroacetic acid (70/30). The peaks at (1) for C=C double bond (2) for CH2 group which are due to the presence of LA.

0.005 PET Control.001.001.1r.esp

0.004

0.003

0.002

0.001 (c)

-0.001 (b)

-0.002 Normalized Intensity -0.003

-0.004

-0.005 (a) -0.006

4.25 4.20 4.15 4.10 4.05 4.00 3.95 3.90 3.85 3.80 Chemical Shift (ppm) Figure 5-5: NMR spectra of (a) PET, (b) PET/LA 2 sp bottle sidewall (c) PET/LA 1sp bottle sidewall . The reaction between hydroxyl end of PET and the carboxylic acid of LA is confirmed by the appearance of a peak at 4.03 ppm.

5.1.2 End group concentration

Reactive extrusion of LA with PET was expected to result in a decrease in the concentration of hydroxyl group of PET due to reaction with the carboxyl group of

LA with little change in the carboxyl concentration of PET. Simple blending of LA was expected to result in an increase in concentration of carboxyl end group with no change in the hydroxyl end group concentration. End group analysis was performed using FTIR analysis of base and deuteriated samples of bottle sidewall using a method described in detail by Abdhul Razzak et.al[141]. The hydroxyl and carboxyl end group are located in the region of 3700-3100 cm-1, with peaks for hydroxyl end group were around 3540 cm-1

and carboxyl end group were around 3270cm-1. The concentration of hydroxyl end groups present in the base PET was 74 µeqmol/g so that the estimated maximum equivalent amount of LA that could react with these hydroxyl end groups was 2% by weigh. A plot of nominal scavenger loading (weight % LA fed to hopper) versus the hydroxyl and carboxyl end groups concentration (µeqmol/g PET) is shown in Figure 5-6.

Note that the nominal scavenger loading is defined as the weight fraction of LA fed to the hopper in the initial processing step and does not account for any potential loss of LA during processing. In both the cases of single stage and two stage processing, a decrease in hydroxyl end group concentration was observed when linoleic acid was added to PET.

The equivalent concentration of carboxylic acid end group for 0.5% loading was 18

µeqmol/g of LA. Analysis of hydroxyl end group for PET following two stage processing indicates that all of the linoleic acid reacted with the PET end group. However, the decrease in the hydroxyl end group concentration was smaller for the single stage process than that observed for the two stage process indicating that the reaction did not reach completion. In the two stage process the decrease in the hydroxyl end group compared well with the theoretical decrease however, for the single stage process it was observed that not all the LA was bound to PET.

The carboxyl end group concentration of PET/LA systems did not show a change in relative to the base PET for the two stage process as shown in Figure 5-6. This is consistent with complete reaction to form a PET terminated LA and no unbound LA.

The two stage process includes formation of pellets in a twin screw extruder with longer residence time that would encourage reactive extrusion. This is consistent with complete reaction between LA and PET. The concentration of the carboxyl end group, in the single 100

stage process was greater than that in the control PET as shown in Figure 5-6, indicating the presence of free linoleic acid in the mixture. Since there are free LA molecules in the matrix of PET following single stage processing, the question to be asked would if those free molecule migrate from the PET/LA blends with time. For this purpose solvent extraction and weight loss studies were performed on bottle samples.

COOH], µeqmol/g of PET PET COOH],of µeqmol/g 40 -

OH] [ and 20 -

Conc of [ of Conc 0 0 0.2 0.4 0.6 0.8 Scavenger Loading ( weight %)

Figure 5-6: Concentration of hydroxyl and carboxyl end group from bottle sidewall for base PET and PET/LA mixture. Where hydroxyl end group as a function of linoleic acid loading are indicated by for two stage process ( ), and for single stage process ( ). The carboxyl end group as function of linoleic acid loading are indicated by for two stage process ( ) and single stage process ( ).

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5.1.3 Migration of Linoleic Acid

The potential for migration of linoleic acid from the PET was monitored using extraction from pellets from two stage process and preforms produced by the single and two stage processes. A physical blend of powdered PET with 1% LA was used as control for extraction studies. In all cases, the samples were ground in liquid nitrogen to produce a powder to facilitate extraction. Chloroform D was used as the extraction solvent because it does not dissolve PET or interfere with distinct FTIR peaks of LA.

FTIR peak locations for the LA and PET are given in Table 5-2. Of specific interest are the peaks at 2800-3000 cm-1 for methyl bending and 1712 cm-1 for the carboxyl peak that were used to track the presence of LA in the extraction solvent. In order to qualitatively understand the nature in which linoleic acid was present within the polymer, extraction was conducted on PET and PET/LA pellets and preforms. If unreacted linoleic acid was present within the PET it would dissolve in chloroform D during the extraction process.

Table 5-2: Peak location of functional groups for LA and solvent in extraction study.

Peak Location Material Functional group cm-1

CH 2800-2900 Linoleic acid 2

-COOH 1720

Chloroform- D 900,730

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The FTIR spectra of the extract for (a) PET+ LA physical blend (1%), (b)

PET (c) PET/LA 2sp pellets (d) PET/LA 2sp preform and (e) PET/LA 1sp preform are shown in Figure 5-7. As expected there were no peaks for PET or LA in the base PET extract. The extraction of physical blend (a) shows distinct peaks for LA for methyl bending (Position 1) and carboxyl peak (Position 2). The extract did not contain any linoleic acid for two stage pellets or preforms suggesting that all of the linoleic acid was bound to PET (spectra c and d). For the single stage process samples (spectra e), linoleic acid was extracted from the perform suggesting that some of the linoleic acid added in the single stage process remained unbound. While it is possible that some of the LA reacted with the PET end group, end group analysis and extraction studies indicate that there was some unbound LA present in the PET/LA 1sp sample.

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(1) (2)

(e)

(d)

(c)

(b)

(a)

4000 3500 3000 2500 2000 1500 1000 500 Wavenumber cm-1

5.1.4 TGA

Thermal gravimetric analysis was utilized to determine the amount of unbound LA within PET, following the methods described in section 3.2.5.4. Physical blends were prepared by mixing finely powdered PET with LA monitoring weight loss via TGA. LA was added at 0.25% to 7% by weight with weight loss shown in Figure 5-8 and in Table 5-3. The physical blend of 1.5 wt% LA showed a weight loss of 1.4 wt.% which is consistent with the nominal physical blended systems. Similar results were seen 104

for physical blends up to 7 wt% LA and PET powder shown in Figure 5-8. The weight loss from these blends corresponded to weight ratio of LA in the physical blends. The onset of weight loss occurred at 130oC for the physical blend which is consistent with the evaporation of the LA (Boiling point 230oC) from the surface of PET powder. Note that at higher feed concentrations of LA, the weight loss was lower than the nominal loading which may be due to loss of LA during the blending process.

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100 (a) (b) 99

% Weight Loss Loss Weight % 95

(e) 94

93 0 50 100 150 200 250 300 350

Temperature,oC

Figure 5-8: Weight loss curves of physically blended samples of PET+ LA, to determine the nature of the weight loss curve obtained when heated to 300oC at a rate of 5oC/min. Physical blends of PET with varying % of LA (a) 0% (b) 0.5% (c) 1.5% (d) 2.5% and (e)

7%.

105

Table 5-3: Weight loss observed for physical blends for various loading of physicals blends. The weight loss was obtained at 250oC

LA loading into PET Weight Loss (Physical blends) % 0 0

0.5 0.50

1.5 1.4

2.5 2.19

7 6.17

100 (a) (b) (c) (d)

99.5 (e) (f)

99 % Weight Loss Weight % 98.5

98 0 50 100 150 200 250 300 350 Temperature,oC

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Thermal gravimetric analysis was used to monitor the weight loss of PET and

PET/LA samples as function of processing to confirm the presence of unbound LA.

There was no loss in weight for the base PET with increase in temperature up to 300oC as shown in Figure 5-9 (a). The weight loss following each processing step for the two stage process are shown in Figures 5-9 (b) to (d) the total weight loss at 250oC decreased after each processing step from pellets to preforms and bottle for the two stage process as shown in Table 5-4. Weight loss at 250 oC was used as an indicator of concentration of unbound LA since the PET exhibited little weight loss at this temperature.

The weight loss at 250 oC for the two stage pellets was around 0.16% which is lower than the nominal 0.5%. The two stage preforms have lower weight loss which confirms the results from end group and extraction studies for the two stage systems. In the case of single stage process, the onset of loss of LA was observed at 120oC for the preform with a weight loss of 0.3 %. Based on the TGA the preform had unbound LA in the PET matrix following single stage processing and some bound LA. End group analysis also confirmed that there was both bound and unbound LA present.

The presence of LA within PET following each processing stage was confirmed using NMR, TGA and end group analysis methods. The reaction between hydroxyl end group of PET and the carboxyl group of LA to produce the PET terminated LA was confirmed for the two stage process. However, single stage processing resulted in the combination of blending and reactive extrusion so that there are two populations of LA within the PET bottles.

Finally, end group analysis confirmed that the two stage processes results in complete reaction and single stage process in partial reaction. The nature of inclusion of 107

LA within PET (ie. Blending or reaction with end group) can affect the physical properties of PET as discussed in detail below.

5.2 Characterization of PET/ LA systems

5.2.1 Melt IV

The melt IV of PET/LA were determined following each processing step to explore the impact of processing the PET and PET/LA systems on molecular weight and processing condition. A material with low IV will not have sufficient melt strength to obtain the desired products. Melt IV can also be used to determine apparent molecular weight following each processing stage. The melt IV values of pellets and preforms are shown in Table 5-4. The addition of LA resulted in a reduction in Melt IV, which can be associated with a reduction in the average molecular weight due to the presence of small molecules and/or a degradation of PET following the addition of LA. When the pellets were processed into preforms it can be noted that there was a reduction in IV relative to

PET but a more significant reduction was seen for PET/LA following two stage processes. This may be due to residence time in two stage process that leads to greater degradation of PET. The single stage process preforms had similar IV as that obtained for two stage process for the same loading.

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Table 5-4: Weight loss analysis of PET and PET/LA samples – pellets to bottles.

Pellets Preform Bottle

Melt IV Melt IV Weight Loss dl/g Weight Loss dl/g Weight Loss %

0.68 0.72 PET 0 (0.01) 0 (0.03) 0

0.16 0.07 0.09 0.62 0.57 PET/ LA 2sp (±0.02) (0.02) (±0.03) (0.01) (±0.02)

0.33 0.58 0.30 PET/ LA 1sp N/A (±0.03) (0.03) (±0.01)

5.2.2 Thermal –Physical Properties of PET/LA systems

An understanding of the impact of additives on the thermal transition temperatures of polymers is important in bottle processing and the end use of the polymer. Therefore the effects of inclusion of LA on the thermal transitions temperatures of PET were determined for pellets, preforms and bottles prepared using both single and two stage processes. Specifically, analysis of the second heating cycle from differential scanning calorimetry was used to establish the thermal transition temperatures of the PET and PET/LA samples. The transition temperatures shown in Table 5-5 are from the

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second heating run after the thermal history was erased. Glass transition (Tg) and crystallization (Tc) temperature remained fairly constant with respect to the control PET for PET/LA 2sp pellets. In the case of both single and two stage processing, the preform showed a reduction in Tg which is consistent with addition of small molecule in polymer.

The reductions in glass transitions temperature were due to plasticizing effect of the LA on the PET which was confirmed by the reduction of Melt IV. The Tc was lower for the two stage process but in case of single stage process was the higher than base PET. The melt temperatures were similar for all the samples which shows that the addition of LA did not have any effect on PET crystal melting. The Tg of the preforms determine the operating condition for blow molding. Tg for PET/LA 2sp and 1sp preforms were similar and hence all the bottles were blown at the same conditions. The side walls of the bottles were analyzed for crystallinity from the first heating cycle from DSC as discussed in

Section 3.3.5.4.2. The first heating ramp showed no crystallization peaks therefore Hc = 0

[27, 167] the melting peak was noted from which the percentage crystallinity was obtained using equation 5-1.

Eq 5-1 H −Hc Crystallinity = 푚 푐 H표

where Hm is the enthalpy absorbed during melting, Hc is the heat of crystallization,

Where Ho – is the maximum heat absorbed by 100% crystalline is 140 J/g[154-156]

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Table 5-5: Transition temperature of PET and PET/LA systems.

Pellets Preform Bottle side wall

Tg Tc Tm Tg Tc Tm Tg Tc Tm

(oC) (oC) (oC) (oC) (oC) (oC) (oC) (oC) (oC)

79.1 145.5 243.2 79.5 149.9 238.6 79.3 156.4 247.2 PET (±1.0) (±0.2) (±0.1) (±0.6) (±1.6) (±0.7) (±0.3) (±0.3) (±1.5)

PET/LA 79.4 145.2 243.5 75.1 134.7 244.4 79 137.9 248.0

0.5 2sp (±1.2) (±0.5) (±0.2) (±1.0) (±0.9) (±0.5) (±0.2) (±2) (±1.7)

PET/LA 75.1 154.7 244.4 78.2 154.1 247.3 N/A 1sp (±1.2) (±1.1) (±1.6) (±1.3) (±0.8) (±1.3)

The effects of LA loading and the processing method on the physical properties of

PET are given in Table 5-6 for each processing step. The density of PET bottle side wall was slightly higher than that of the PET/LA bottle side wall irrespective of processing method which is consistent with presence of low density additive (density of LA =0.9 g/cc). The Young Modulus and yield strength for tensile testing of PET and PET/LA bottle sidewalls produced by the two methods were similar to the control PET bottle.

Optical clarity for the bottles sidewall was measured with respect to % haze and the inclusion of LA on haze was monitored. The PET and PET/LA 0.5% two stage bottle sidewalls have similar amount of haze but the single stage process showed a decreased

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level of haze. Therefore, the addition of LA did not cause any opaqueness to the sidewall when 0.5% loading was used.

Table 5-6: Density, mechanical properties and haze level of bottle side wall

Delta Hm Yield Density Modulus (first Strength %Haze Crystallinity g/cc MPa heating MPa ramp) 5.4 1.356 1172 76 39.4 PET (±1.1) 28% (±.0.0006) (±93) (±2) (±2.03)

6.4 PET/ LA 1.352 1308 80 36.2 (±0.7) 26% 2sp (±.0.0007) (±85) (±2) (±3.52)

PET/ LA 1.352 1021 69 2.5 40.8 29% 1sp (±.0.0005) (±115) (±1.5) (±0.6) (±4.00)

5.2.3 Oxygen permeation

The purpose of including LA within PET was to reduce the rate of oxygen transport through the bottle sidewall by reacting with oxygen. Oxygen permeation rates at

25oC were determined for films cut from bottle side wall as described in detail in experimental section. Studies were conducted on bottle side walls to determine the oxygen transmission rate as function of LA addition. The cumulative oxygen permeated

(Qt) through the PET and PET/LA bottle sidewalls as a function of time are shown in

Figure 5-10. In all cases, the thicknesses of the films were between 10 to 11 mil so this is

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a direct reflection of differences in inherent transport properties of the films. The oxygen permeated through a sample of PET bottle sidewall in Figure 5-10 (a) as the oxygen transmission rate was constant hence the curve would yield a straight line. The inclusion of LA reduced the oxygen permeating through the bottle sidewall samples as represented in Figure 5-10 (b)-(c).

The permeability of the bottle sidewall are given in Table 5-7, along with the

Barrier improvement factor (BIF). The Qt curves of PET/LA systems show that the slope of the line are lower than that of PET which indicated that the addition of LA leads to a reduction on oxygen permeability. The reduction can be due to a combination of effect, oxygen scavenging and impact of LA on microstructure of PET. When rate of reaction of oxygen with the scavenger in PET is lower than diffusion of oxygen would result in reduction of oxygen permeability alone and no time lag could be noticed as discussed in

Chapter 4.

Table 5-7: Oxygen transport properties PET and PET/ LA bottle sidewall.

Permeability BIF CC. mil/(100in2.day. atm) 7.22 PET 1.0 (±0.6) 3.14 PET/ LA 2sp (±0.2) 2.29

3.53 PET/LA 1sp 2.04 (±0.4)

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300 (a) 250

200

Q 150 (b)

CC.mil/100in 100 (c)

0 0 10 20 30 40 Time, days

Figure 5-10: Cumulative oxygen permeated through the bottle side wall (a) PET, (b) PET/ LA 1sp (c) PET/ LA 2sp.

5.3 Conclusion

Linoleic acid was incorporated into PET using two different methods namely two stage and single stage process. The two stage resulted in PET terminated with LA and the single stage resulting in partial reaction was achieved using solely injection molding. The presence of linoleic acid within PET was confirmed using NMR, where C=C were seen in the spectra along with the methyl peak of LA. The reaction with the hydroxyl end

114

group of PET and carboxyl end group of LA was also determined by using NMR. NMR could not be used to quantify the extent of reaction so end group analysis of bottle sidewalls was used. Injection molding results in partial reaction (single stage process) as does reactive extruded of pellets. However, the reactive extrusion followed by injection molding lead to full reaction during the two stage process. Extraction of LA from the

PET were studied using chloroform- D extraction, the two stage process showed no LA in extract indicating it was bound with the PET while the single stage process showed the presence of LA in the extract indicating that some of the LA was in the unbound form.

TGA was also used to verify the quantity of unbound LA, which confirmed that as each processing stage was completed the amount of unbound LA was reduced. The thermal analysis showed that Tg decrease with addition of LA. Melt IV also decreased with addition of LA. The mechanical strength of these bottles were similar to that of PET. The optical clarity of the bottles was determined using haze analysis and both cases showed low haze values. The oxygen permeability of the bottle side wall showed that addition of

LA of 0.5% using the two stage process reduced the permeability by 56% while in the case of the single stage process the reduction was 51%.

While the permeation of oxygen in PET/LA blown bottles were reduced, it is unclear whether this is due solely to oxygen scavenging or effect on polymer microstructure. Therefore, films were produced with LA at concentration upto 2% to analyze effect on microstructure and crystallinity. This will be discussed in Chapter 6 for blending and reactive extruded samples.

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Chapter 6

6. PET Blends and Terminated with LA

Bottles were prepared with linoleic acid at 0.5 wt % using either a single or two

stage methods as discussed in chapter 5. The PET/LA bottles showed a 50% reduction in

oxygen permeation for both cases relative to PET bottle. The LA was incorporated within

the bottle via both blending and reaction to produce PET terminated LA and oriented to

form bottles. While these results are promising, the impact of LA on the microstructure

and mechanism of transport were unclear. In order to determine which mechanism has a

dominant effect on the reduction of oxygen permeation, films were produced using

blends and reactive extrusion of PET/LA to understand the impact of nature of LA on the

properties. These films that were prepared were studied as amorphous and oriented

resulting in strained induced crystalline sample to study effect of LA on microstructure

and properties.

Blends were prepared using a single screw extruder following the procedure

described in 3.2.2.1 where flat sheets were obtained with LA loading of 0.25 to 2% by

weight. These films were amorphous sheets as verified by density and DSC analysis. The

single screw extruder has a very short residence, which does not allow time for reaction

of the end group of PET and LA. The films were stretched bi-axially to prepare oriented

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crystalline films of 25 to 30%. The microstructure, physical and transport properties were monitored as function of LA loading.

A two stage procedure with a twin screw extruder was followed as described in section 3.2.2.2 to obtain PET terminated with LA pellets of loading from 0.25 to 2% by weight. The pellets were made into sheets using a single screw extruder and oriented as described for single stage films. Reactive extruded films of LA with nominal loading of

0.25 and 0.5% by weight were obtained. Higher loading of LA 1 and 2% by weight could not be processed from pellets into sheets. The PET/LA pellets had a relatively low IV following twin screw processing so that, the polymer melt did not have enough melt strength to be pulled by the roller following single screw extrusion. This work distinguish which process has a dominate effect on achieving reduction in oxygen permeation. The effects of loading LA into PET on the properties of the polymer were also determined.

Figure 6-1 gives an overall flow diagram for both processing methods and the various characterizations that were used following each process step.

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Reactive extrusion Films Characterization Pellets (Single screw End group analysis, (Twin screw extruder) extruder) density and Permeation

Characterization NMR, DSC , TGA PET+ and Melt IV Scavenger

Blends Characterization: DSC , Films NMR, TGA , End group (Single screw analysis, density and extruder) Permeation

Figure 6-1: Flow diagram for processing of PET/LA samples using single stage (Blended films) and two stage (Reactive extrusion) and their characterization studies that were conducted on each stage.

The concentration and nature of inclusion of LA within PET was determined using NMR, TGA and end group analysis. The thermal transition was monitored for films made from blends and LA terminated PET pellets made from reactive extrusion so they had one processing step. Crystallization studies were done using a dynamic approach and IV was determined using two methods. Permeation measurements were performed on films which were both amorphous and oriented films with 30% crystallinity. When characterizing these systems the PET/LA systems, NMR, TGA, thermal analysis (DSC) were conducted on pellets and End group analysis, density, oxygen permeation were conducted on films.

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6.1. Presence, nature and quantification of LA within PET

Films with 0.25 to 2% nominal loading of LA were produced using a single stage process and films with 0.25 and 0.5% nominal loading of LA were produced using a two stage process. The goal was to develop films that are blends of PET/LA (single stage process) and those that involve reaction of LA with end group of PET (two stage process). Several methods were used to confirm the presence of LA and any reaction between LA and PET. Inclusion of LA within PET was confirmed using several analytical techniques as discussed in Chapter 3 and used for PET/LA bottles discussed in

Chapter 5.

6.1.1. NMR

Solution NMR was used to confirm the presence of LA in PET and any reaction between LA and PET end group. H-NMR spectra of LA and the base PET are shown in

Figure 5-3 in Chapter 5 with peak designation for each structure listed in Table 6-1. The major peaks of interest for LA were at 5.4 ppm which are due to the presence of C=C bonds and the peak round 2.8 ppm the methyl peak. These are isolated from peaks for the

PET and can be used to demonstrate inclusion of LA in PET.

Solution H-NMR spectra of PET/LA films produced by the single stage process are shown in Figure 6-2 and for pellets from the two stage process are shown in Figure 6-

3. The peaks at 5.4 ppm (Arrow 1) and 2.8 ppm (Arrow 2) were used to indicate presence

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of LA. There is a progressive increase in peak at both locations with increasing nominal loading that is consistent with increased inclusion of LA in PET.

Single stage films shows no reaction between hydroxyl end group of PET and carboxyl end group of LA, as peak at 4.03 ppm was not present as shown in Figure. 6-4.

Figure 6-4 shows the region from 3.85 and 4.10 ppm to focus on the peak which appears due to reaction between COOH of LA and hydroxyl end group of PET. This peak represents an acetate type of compound being formed and the peak represents the CH2 protons from the PET side end, a representation of the structure is shown in Figure 5-3.

In Fig. 6-4 case (f) where complete reaction took place there was a peak at 4.03 ppm which is proof of reaction between hydroxyl end of PET and carboxyl end of LA. These results confirm that films prepared using single screw extruder were blends and were not terminated with LA.

Pellets from twin screw extruder shows the presence of a peak at 4.03 ppm in the solution NMR which confirms that the LA reacted with the hydroxyl end group of PET as shown in Figure 6-5. The increase in LA concentration shows an increase in normalized peaked intensity which is indicative of higher concentration of reacted end groups of LA and PET. The reactive extruded pellets obtained from twin screw extruder show that PET has been terminated with LA. Because the peaks for reaction between end group and LA are relatively small it is difficult to quantify the reaction using NMR.

Therefore, the amount of LA within the PET and the nature in which the LA was present was quantified by end group analysis.

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Table 6-1: Peak Designation for Linoleic acid, base PET and PET/ LA reacted groups.

Peak location

(ppm)

LA CH3 0.90

CH2 in chain 1.33

CH2 (second group from – 1.65

COOH end)

CH2 before and after C=C 2.06

CH2 (near –COOH) 2.36

CH2 ( between C=C bonds) 2.8

CH 5.4

PET Ethylene Glycol in chain 4.78

Benzene ring 8.13

PET-LA CH2-OCO-CH2 4.03

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PET Control.001.001.1r.esp 0.012

0.011

0.010

0.009 (1) (2) 0.008

0.007

0.006

0.005 (e) 0.004

0.003

Normalized Intensity (d) 0.002

0.001 (c)

0 (b) -0.001

-0.002 (a) -0.003

9 8 7 6 5 4 3 2 1 Chemical Shift (ppm) Figure 6-2: NMR spectra of the single stage or blended films prepared (a) PET, (b) 0.25PET (c) 0.5PET (d) 1PET (e) 2PET. The regions around 5.4 ppm (arrow 1) and 2.8 ppm (arrow 2) are due to C=C bonds present in LA. PET does not show any peak in these regions there by confirming the presence of LA.

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0.015 PET Control.001.001.1r.esp

(1) (2) 0.010

0.005 (e)

Normalized Intensity (d)

(a)

9 8 7 6 5 4 3 2 1 Chemical Shift (ppm) Figure 6-3: NMR spectra of reactive extruded pellets prepared (a) PET, (b) 0.25PET (c) 0.5PET (d) 1PET (e) 2PET. The regions around 5.4 ppm and 2.06 are due to C=C bonds present in LA. PET does not show any peak in these regions there by confirming the presence of LA.

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0.005 PET Control.001.001.1r.esp

0.004

0.003

0.002 (f) 0.001 (e) 0 (d)

-0.001 Normalized Intensity (c) -0.002 (b) -0.003 (a) -0.004

4.10 4.05 4.00 3.95 3.90 3.85 Chemical Shift (ppm) Figure 6-4: Zoomed NMR spectra of single stage or blended films prepared (a) PET, (b) 0.25PET (c) 0.5PET (d) 1PET (e) 2PET and (f) PET/LA (Bottle side wall). This is to show that using a single screw extruder blends were obtained as there was no peak at 4.03 which is present in reacted samples.

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PET Control.001.001.1r.esp 0.007

0.006

0.005

0.004

0.003

0.002 (e)

0.001

Normalized Intensity (d) 0 (c) -0.001 (b) -0.002

-0.003 (a)

4.15 4.10 4.05 4.00 3.95 3.90 3.85 3.80 3.75 3.70 3.65 3.60 3.55 Chemical Shift (ppm) Figure 6-5: Zoomed NMR Spectra of reactive extruded pellets prepared (a) PET, (b) 0.25PET (c) 0.5PET (d) 1PET and (e) 2PET. The twin screw extruder has confirmed reaction between the end groups of COOH of LA and OH of PET. The increase in concentration of LA has shown an increase in peak intensity which confirm with higher loading higher reaction has taken place.

6.1.2. End group

The concentration of carboxyl and hydroxyl end group of PET were determined using an FTIR technique with films as explained in detail in section 3.2.5.1.1. This method was established by Al-Abdul Razzak et al to monitor the end group of PET as function of processing conditions [141]. The presence of fatty acid in the PET/LA samples was confirmed by solution NMR and in the case of two stage process reaction was also confirmed. End group concentrations were determined following the FTIR 125

technique as shown in Figure 6-6 and Table 6-2. When LA was blended into PET, the carboxyl end group concentration would increase due to additional carboxyl concentration of LA. The expected increase in carboxyl end group due to the presence of

LA can be calculated based on the weight % of LA added as is represented by the dash line in Figure 6-6. The carboxyl end group concentration show an increase while hydroxyl end group remains fairly constant, thus confirming that linoleic acid is present within the polymer in the form of a blend. At lower loading (0.25, 0.5% loading) the carboxyl end group increase due to LA was consistent with theoretical carboxylic acid end concentration. At higher loading (1 and 2% loading) the measured carboxyl end group was lower than theoretical value, this decrease could be due loss in LA that occurred during processing on some reaction with PET. The hydroxyl end group of PET remains constant which again confirms that reaction with PET did not occur. The end group concentrations are shown in Table 6-2 along with weight loss data. The constant value of hydroxyl concentration for the single screw extrusion films confirms no reaction has taken place. When reactive extruded pellets were made into films using a single screw extruder no further reaction would be expected to takes place and the decrease in hydroxyl end group can be attributed to reaction that had taken place in twin screw extruder during pellet formation.

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100 -OH End Group

90 80 70 Theoretical -OH

)mol/g] 6

- 50 40 -COOH End Group [(x10^ 30 20

End Group Concentration Group End Theoretical - 10 COOH 0 0 0.5 1 1.5 2 2.5 Scavenger Loading (Weight %)

Figure 6-6: End group analysis of linoleic acid in PET and PET/linoleic acid formed by single stage process.

Pellets made using twin screw extruder were made into film in single screw extruder to determine the end group concentration. The end group concentration of these two stage films shows that the hydroxyl end group decreases relative to base PET which confirms reaction of hydroxyl end group of PET and carboxyl end group of LA as shown

Figure 6-7 and Table 6-3. There is slight increase in carboxyl end group concentration relative to base PET which shown that there is some unbound LA. The amount of LA that has been bound to PET can be determined from the decrease in hydroxyl end group.

NMR of the pellets has shown that reaction between the end groups took place which was confirmed by the end group analysis of the two stage films. The NMR spectra have shown the presence of LA with PET and if reaction had taken place between the end

127

groups. End group analysis confirmed the NMR result and was used to quantify the amount unbound or bound LA that are present within PET/LA systems. These results confirmed that the single screw extruder produced blends and the twin screw extruder can produce PET terminated LA. From this point the single screw stage process films will be referred to as blends (B) and those produced using two stage process will be reactive extruded (RE).

100 -OH Theoretical 90 80 70 RE Film -OH

)mol/g] 6

- 50 40 RE Film -COOH

[(x10^ 30

20 -COOH End Group Concentration Group End 10 Theoretical 0 0 0.2 0.4 0.6 Scavenger Loading (Weight %)

Figure 6-7: End group analysis of PET and PET/LA two stage or reactive extruded films.

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% Unbound LA Scavenger TGA weight loss -OH -COOH based on End concentration @ 250oC group analysis

66.84 24.30 0 0 0 (±0.48) (±0.97) (±0)

66.59 38.72 0.22 0.27 0.25 (±0.82) (±1.0) (±0.02)

69.0 41.18 0.47 0.46 0.5 (±0.88) (±2.63) (±0.04)

63.92 45.25 0.65 1 0.67 (±0.4) (±0.3) (±0.03)

67.90 58.25 0.87 2 0.96 (±3.4) (±0.45) (±0.06)

129

% Bound LA TGA weight loss Scavenger -OH -COOH based on End @ 250oC concentration group analysis (Pellets)

68.37 22.13 0 0 0 (±2) (±0.25) (±0)

64.56 25.17 0.13 0.25 0.11 (±0.42) (±1.25) (±0.02)

56.62 30.78 0.11 0.5 0.33 (±0.76) (±0.18) (±0.01)

0.27 1 NA NA NA (±0.05)

0.22 2 NA NA NA (±0.06)

130

6.1.3. TGA

End group analysis of PET/ LA blended films show an increase in the carboxylic end group concentration which means the LA is unbound within PET which can be confirmed using TGA. PET and PET/LA systems were analyzed by TGA at ramp of

5oC/min upto 300 oC. The weight losses that were obtained can be related to the concentration of unbound LA included into PET, which is shown in Table 6-2 for the single stage films.

The weight loss at the lower loading of 0.25% and 0.50% yielded a weight loss similar to nominal loading into PET during processing and is consistent with end group analysis. TGA and end group methods for 1 and 2 weight % loading in blends confirm that the amount of LA is lower than initial nominal loading of LA with PET. There is no indication of reaction so this was attributed to loss during processing.

When two stage processes was used, the weight loss was lower than the nominal loading in PET there by confirming that reaction took place but not complete reaction.

There is some unbound linoleic acid shown in Table 6-3, which is consistent with end group analysis as well. Note that the % bound LA is shown in Table 6-3 from end group analysis. The amount of decrease in hydroxyl end group gives a measure of the amount of

LA that has reacted with PET. The amount of unbound LA was determined from TGA based on the weight loss. The increase in carboxyl end group was consistent with TGA result. When summed up from the end group and TGA gave values close to the nominal amount of LA that was added into PET. 131

Thus using NMR, end group and TGA on PET and PET/ LA system the presence of LA within PET and the nature in which it was present were determined. The single stage PET/LA films will be referred to as PET 0.25 B, PET 0.5 B, PET 0.65B and PET

0.9 B based on the amount of unbound LA that were present. For the PET/LA reactive extruded, samples will be referred to as PET 0.11RE, PET 0.33RE, PET 1RE and PET

2RE, the lower loading are based on the bound LA and the higher loading are based on the nominal loading as films that were not produced as outlined in Table 6-4.

Table 6-4: Nomenclature for the Blend and Reactive extruded PET/LA systems.

Nominal loading Blends Reactive Extruded

(Weight %)

0 PET B PET RE

0.25 PET0.25 B PET 0.11 RE

0.50 PET 0.5 B PET 0.33 RE

1 PET 0.65 B PET 1 RE

2 PET 0.9 B PET 2RE

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6.2. Characterization of PET/ Linoleic acid systems:

The effects of inclusion of LA into PET on the physical and thermal properties, density of samples were determined for both films and pellets. The effect of crystallization of PET due to the addition LA was also determined as this is critical for processing. Average molecular weight of PET and PET/LA samples were determined using melt IV and solution IV methods.

6.2.1. Density

The density of PET and PET/LA films were analyzed to determine the effect of inclusion LA on the chain packing of PET. Density of films can be used to calculate fractional free volume of the polymer. It has to be noted that totally amorphous PET has a density 1.335 g/cc from literature [14, 27], the density of the control PET is lower than this literature value which may due to the presence of CHDM as copolymer in the base

PET[8]. The density of LA is 0.902 g/cc as supplied by Sigma Aldrich. PET/LA blends show a decrease in density of the films with an increased in loading of linoleic acid when compared to PET as shown in Table 6-5. Density of PET films can be used to determine the fractional free volume of the polymer. The fractional free volume (FFV) was calculated based.

Eq 6-1 FFV= (V-Vo)/ V

133

V is the specific volume of the polymer (inverse of density)

Vo is specific volume of a glassy polymer, obtained by a group contribution method described by Van Krevelen. The Vo for the PET was estimated based on contribution to occupied volume of the various groups present in the polymer.

For PET/LA system

Vo = wV퐿퐴 + (1 − w) V푝표 Eq 6-2

Where w- is the fraction of linoleic acid, present with the PET/LA systems, Vpo is Van

Krevelen volume based on groups present in the polymer. The VLA is a dilutant with value of 0.6733 cc/g from the group contribution method.

Table 6-55 show the fractional free volume of the PET/LA blended films and

Table 6-6 shows the fractional free volume of PET/LA for the reactive extruded films.

The fractional free volume of the PET/LA films was determined from the density, following the same method as PET. If the inclusion of small molecules has a free volume effect there would have been a decrease in the fractional free volume, this decrease in fractional free volume has been related to reduced permeability of gases [27, 77].

134

Table 6-5: Density and free volume of PET and PET/linoleic acid blends.

Specific Specific Free Fractional Free Sample Density (g/cc) volume volume Volume

1.3278 0.753 PET B (±0.0006) 0.101 0.156

1.3278

PET 0.25 B (±0.0003) 0.753 0.101 0.156

1.3270 PET 0.5B 0.754 0.102 0.156 (±0)

1.3255 PET 0.62 B 0.754 0.103 0.157 (±0)

1.3234 PET 0.9 B 0.756 0.103 0.158 (±0)

135

Table 6-6: Density and free volume of PET and PET/LA reactive extruded films.

Specific Free Fractional Sample Density (g/cc) Specific volume volume Free Volume

PET RE 1.3278 0.753 (±0.0006) 0.101 0.155

PET 0.11 RE 1.3278

(±0.0005) 0.753 0.101 0.155

PET 0.33 RE 1.3267 0.754 0.102 0.156 (±0.0004)

The blends and reactive extruded films have a similar density fractional free volume of the PET/LA systems shows similar FFV as PET or a slight increase. There is no indication of bulk changes in chain packing or overall free volumes

6.2.2.Differential scanning calorimetry (DSC)

Thermal analysis was conducted on PET and PET/LA systems to determine transition temperature as function of LA loading and processing as shown in Table 6-7 and 6-8. The samples were films for blended system and pellets for reactive extruded systems, as both systems have only one processing stage. Glass transition temperature of

PET/LA systems decrease with increasing loading relative to the control PET which has been noted with the addition of low molecular weight additives[118]. Crystallization

136

temperature decreases with increasing loading LA into PET. The addition of LA into the polymer makes it crystallize sooner relative to control PET. Reduction in crystallization temperature has been noted when antiplasticizers were introduced into PET [27, 77].

However the melting point does not decrease with increased linoleic acid loading. This trend has been noted for blended films and reactive extruded pellets.

Table 6-7: The thermal effect of adding linoleic acid as blends in PET as measured by

DSC.

Delta Cp Delta Hc Delta Hm Sample Tg Tc Tm J/g*C J/g J/g

79.36 0.32 146.73 34.45 241.50 30.175 PET (±0.41) (±0.01) (±0.91) (±7.00) (±0.49) (±0.18)

PET 0.25 78.85 0.28 143.76 33.84 242.82 30.254

B (±0.21) (±0.03) (±0.01) (±9.75) (±0.01) (±1.83)

78.63 0.302 142.12 34.06 243.63 31.712 PET 0.5 B (±0.08) (±0.03) (±0.49) (±7.85) (±1.13) (±1.59)

243.16 PET 0.65 77.37 0.302 137.19 28.796 34.371 5 B (±1.22) (±0.05) (±4.67) (±0.41) (±0.17) (±0.40)

76.14 0.257 138.89 24.179 243.16 36.664 PET 0.9 B (±0.28) (±0.09) (±3.30) (±0.30) (±0.40) (±0.17)

137

Table 6-8: The thermal effect of adding linoleic acid as reactive extruded pellets as measured by DSC.

Delta Cp Delta Hc Delta Hm Sample Tg Tc Tm J/g*C J/g J/g

79.31 0.253 147.87 27.21 244.46 30.282 PET (±0.41) (±0.04) (±0.91) (±7.00) (±1.37) (±0.2)

PET 0.11 78.74 0.302 143.25 27.07 243.90 30.984

RE (±0.48) (±0.02) (±0.01) (±1.0) (±0.7) (±0.70)

PET 0.33 78.49 0.29 140.49 28.41 244.23 36.30

RE (±0.29) (±0.03) (±0.49) (±1.71) (±0.20) (±0.17)

77.54 0.32 138.95 27.46 244.77 36.01 PET 1 RE (±0.24) (±0.05) (±4.67) (±7.67) (±0.10) (±0.30)

77.20 0.301 139.28 27 244.77 36.53 PET 2 RE (±0.35) (±0.06) (±3.30) (±3.54) (±0.60) (±0.50)

With increase in loading of linoleic acid there was a decrease in the crystallization temperature of the PET/linoleic acid blended films. This may affect crystallization during processing so that the effect of linoleic acid on the crystallization of PET was monitored using a dynamic crystallization. This study will give information about the nature in which crystallization would occur in the polymer during processing including strain induced crystallization. The polymer blends were cooled at cooling rates from 10-

40oC/min and the minimum cooling rate required to obtain a completely amorphous polymer system (ie. to have zero change in enthalpy of crystallization when cooled from

138

the melt) was determined. The addition of LA increased the rate of cooling that was required to obtain completely amorphous polymer system as shown in Tables 6-9 and 6-

10. The addition of LA in both cases show a similar trend where the rate required to obtain 100% amorphous polymer increased with respect to the control PET.

Figure 6-8 represents the change in enthalpy of crystallization on cooling from the melt as an inverse function of cooling rate for the PET and PET/LA blended films. This graph was used to determine the cooling rate required for zero enthalpy change in crystallization which is represented in Table 6-9. Figure 6-9 shows the plot of enthalpy vs inverse of cooling rate for the reactive extruded pellets and the cooling rate required are given in Table 6-10. This would affect how the polymer would crystalize and processes required to obtain higher level of crystallinity would improve the barrier properties of

PET. This is indicative of plasticization of PET by LA on bulk scale.

139

45 40 35 (a)

30 (b) (c) 25 (d) 20

Delta H J/g J/g Delta H (e) 15 10 5 0 0 0.01 0.02 0.03 0.04 0.05 1/ Cooling Rate (min/C)

Figure 6-8: Effect of loading LA on crystallization of PET from melt - (a) PET 0.9 B, (b) PET 0.65 B, (c) PET 0.5 B, (d) PET 0.25 B and (e) PET.

Table 6-9: Cooling rate required to obtain amorphous polymer.

Sample PET PET 0.25 B PET 0.5 B PET 0.65 B PET 0.9 B

Intercept 44 51 53.5 67 72

(oC/min)

140

40 35 30 (a)

(b) 25 (c) 20 (d)

Delta Delta H, J/g 15 10 (e) 5 0 0 0.01 0.02 0.03 0.04 0.05 0.06 1/Cooling rate, (min/C)

Figure 6-9: Effect of loading LA on crystallization of PET from melt - (a) PET 2 RE, (b) PET 1 RE, (c) PET 0.33 RE, (d) PET 0.11 RE and (e) PET.

Table 6-10: Cooling rate required to obtain amorphous polymer.

Sample PET PET 0.11 PET 0.33 PET 1 RE PET 2 RE

RE RE

Intercept 38 52 62 65 61

(oC/min)

Crystallization kinetics can be obtained from dynamic cooling studies following Ozawa modified Avarami Equation 6-3.

log[− ln(1 − 푎)] = log 퐾 − 푛 log 푅 Eq 6-3

Where a is the amount of transformed material at temperature T, R is the cooling rate, K is the rate constant, which is a function of nucleation growth rates and n is the

141

avarami exponent which describes qualitatively the mechanism of crystallization[153].

The values of n can vary from 1 to 4 depending on the mechanism of crystal growth, 1-

Rod – like growth from instantaneous nuclei, 2 - Rod – like growth from sporadic nuclei,

2 - Disk – like growth from instantaneous nuclei, 3 - Disk – like growth from sporadic nuclei, 3 - Spherulitic growth from instantaneous nuclei and 4- Spherulitic growth from sporadic nuclei [14], some of the values have two mechanism and cannot be distinguished. The K and n values were determined for the various loading of LA via equation 6-3 as shown in Table 6-11-11 for the blended films and Table 6-12 for the reactive extruded pellets. Based on the K be noted that LA increases the rate of crystallization and the avarami exponent remain constant. The blends and reactive extrusion has shown similar results. The addition of LA has shown to increase the rate of crystal growth while the mechanism of nucleation would form spherulitic growth with instantaneous nuclei and disc – like growth from sporadic nuclei.

Table 6-11: Non isothermal crystallization studies to determine n and K, PET and PET/LA blends Temperature PET PET 0.25 B PET 0.5 B PET 0.65 B PET 0.9 B

n K n K n K n K N K

180 3.4 6.4 3.3 8.9 2.9 6.12 3.3 10.85 2.7 10.9

170 3.1 8.85 2.8 9.34 2.8 11.41 3.0 13.35 2.5 12.35

160 3 11.47 2.9 14.72 2.4 13.92 2.8 17.658 2.5 17.66

150 2.9 16.47 2.6 13.66 2.5 16.94 3.1 20.2 2.6 21.95

142

Table 6-12: Non isothermal crystallization studies to determine n and K, PET and PET/LA reactive extruded. Temperature PET 0.11 PET PET 0.33 RE PET 1 RE PET 2 RE RE

n K n K n K n K n K 180 3.4 3.5 2.7 4.45 2.7 5.322 2.6 5.38 2.7 7.3

170 3.6 10.07 2.7 7.74 3.2 14.84 3.1 19.1 2.2 18.8

160 3 15.12 2.6 8.15 2.9 14.64 3.6 17.64 2.2 16.8

150 3.1 12.19 2.9 21.1 3.0 22 2.6 16.02 2.5 17.0

6.2.3. Intrinsic Viscosities

The intrinsic viscosities of the films were determined to understand the effect on

PET from the inclusion of LA using Melt IV and solution IV methods. This gives an apparent molecular weight of the PET/LA systems and monitors the plasticization effect

LA had on PET.

6.2.4.1. Solution IV

Solution IV was determined by ASTM D 4603- 03 for PET and PET/ LA systems dissolved in a Phenol/ 1,1,2,2 tetracholroethane (60/40 weight%) solution. The viscosity of the PET and PET/LA solution were determined from which inherent viscosity (IV) was calculated using a Billmeyer relationship which has been described in 3.2.5.5.1. The

143

values obtained for the PET/LA blended films are shown in Table 6-13 and the PET terminated LA pellets are shown in Table 6-14. When solution IV of physical blends of powder PET and LA were measured the presence of LA did not have any effect on solution IV.

6.2.4.1. Melt IV

Melt IV for PET and PET/LA blended films were determined using curves of complex viscosity vs shear rate as shown in Figure 6-10. Curves for higher loading

Figure 6-10 (c-e) overlapped and could not be easily distinguished distinguishable. The

PET curve has a much higher complex viscosity than PET/LA systems. The shape of these curves remain the same, however the viscosity of the sample was significantly reduced with addition of LA in both cases (blends and reactive extrusion). The melt IV of blends shows an initial drop upto to 0.5 wt% and remains constant with increase loading.

There is little change in solution IV over this range. This is evident that fatty acid has a plasticizing effect on PET.

The reactive extrusion pellets show a more gradual reduction with the addition of

LA indicating that there is less unbound LA and these results when compared to IV of the solution methods are consistent. The presence of unbound LA in PET has a plasticizing effect which resulted in a reduction of melt viscosity of PET/LA. When fatty acid were introduced into a polymer in literature it has known to reduce torque required for processing [118]. The melt IV values of the PET and PET/LA systems were determined from the melt viscosity and are shown in Table 6-13 for the PET/LA blended films and

Table 6-14 for PET terminated LA pellets. 144

Viscosity vs. Shear Rate 270°C 1000

(a)

s) - (b)

100 (c), (d), (e)

Complex Viscosity (Pa Viscosity Complex 10 1 10 100 1000 Shear Rate (rad/s)

Figure 6-10: Melt viscosity curves of PET/LA blended films of (a) PET, (b) PET 0.25 B, (c) PET 0.5B, (d) PET 0.65 B and (e) PET 0.9 B at 270oC.

Table 6-13: Intrinsic Viscosity of PET and PET/LA blended films

Solution IV Melt IV

dL/g dL/g

PET 0.75 0.71

PET 0.25 B 0.65 0.53

PET 0.5 B 0.66 0.46

PET 0.65 B 0.65 0.47

PET 0.9 B 0.61 0.48

145

Table 6-14: Intrinsic Viscosity of PET and PET/LA reactive extruded pellets.

Solution IV Melt IV

dL/g dL/g

PET RE 0.73 0.72

PET 0.11 RE 0.67 0.68

PET 0.33 RE 0.65 0.63

PET 1 RE 0.59 0.58

PET 2RE 0.58 0.52

The solution viscosity analysis showed that the addition of LA into PET in the form of blends resulted in slight decrease in IV which did not change with concentration of LA as shown in Table 6-13. The decrease in solution IV may be due to plasticizing of

PET while processing PET in the presence of LA, as physical blends of powdered PET and LA in different ratios gave a solution IV value similar to PET that was used. The

Melt IV of PET/LA show a significant decrease that could be due to the improved flow of

PET melt as linoleic acid acts as a plasticizer [118].

When intrinsic viscosities of reactive extruded pellets were determined there was no change in IV obtained using solution and melt methods. For cases where PET was terminated by LA the overall IV of the polymer was reduced by the addition of low molecular weight LA to the polymer chains. The values determined using both methods as shown in Table 6-14.

146

6.2.4. Oxygen permeation

The rate of oxygen passing through the PET and PET/LA film was studied over 15 days, with both amorphous and oriented films with crystallinity of about 30%. The impact of processing method and LA content on the transport properties of PET/LA films will be discussed.

6.2.4.1. Oxygen permeation PET and PET/LA Blends

Amorphous:

The amorphous nature of the films was confirmed using first run of DSC, as shown in

Figure 6-11 were two distinct peaks in the form of crystallization and melting peak were present. There is a small difference in the enthalpy of crystallization and melting so the percentage of crystallinity were around 10%, for all the PET and PET/LA prior to stretching. The cumulative amount of oxygen that passed through the amorphous films of PET and PET/LA are shown in Figure 6-12 for blended systems. The curves of PET and PET/LA showed no time lag period (region over which no oxygen passes through the film). This may be due to the fact that the thin films exhibited breakthrough before first point. The methods used for permeation is designed to accommodate thick films and bottle sidewall where time lag may be several days. The films used were 10 times thinner than the bottle sidewall and the estimated time lag based on the diffusion coefficient of

4.8 x 10-13 m2/sec [81, 86] for PET where less than 12 hrs. Therefore, it would be difficult to detect break through or time lag for base PET.

147

When linoleic acid is diluted into a non-reactive medium the apparent rate would decrease which has been discussed in Chapter 4. This would also occur when introduced into PET but the reaction with oxygen would be a slow process as established by Dr.

Cameron with Thiele modulus less than 10 [112]. At lower Thiele modulus (i.e. lower rate kinetics for scavenging) a decrease in permeability would be observed relative to base material as oxygen was being scavenged. The amount of oxygen that permeates through an amorphous PET/LA blended films were slightly lower than PET. The permeability of base PET and PET/LA blends are shown in Table 6-16.

Figure 6-11: First heating ramp of DSC to determine the amorphous nature in PET film.

148

300

250

(a),(b),(c),(d),(e)

) 2

200

Q 150

100 CC.mil/(day.100in 50

0 0 5 10 15 20 25 30 Time, days

Figure 6-12: Cumulative amount of oxygen permeating through amorphous PET and PET/LA films. (a) PET, (b) PET 0.25 B, (c) PET 0.5B, (d) PET 0.65 B and (e) PET 0.9 B

The oriented nature of the films was determined using the first heating ramp of the DSC shown in Figure 6-13, where only one peak was noted due to melting. The lack of crystalline peak around 150oC was observed for all oriented films their crystallinity was around 30%. The conditions at which films were oriented and the crystallinity are shown in Table 6-15. The oxygen permeability of base PET was reduced by 30% relative to amorphous PET when the films were oriented with crystallinity of about 30%. The orientation of PET/LA blended films resulted in larger reduction in oxygen permeation than crystalline base PET. The cumulative amount of oxygen that permeates through oriented crystalline PET and PET/LA films are shown in Figure 6-14. The inclusion of

LA into PET matrix results in a reduction in oxygen permeation with the largest decrease for sample with 0.9% loading of LA. The permeability values and the barrier

149

improvement factor (BIF) of PET/LA oriented films are also given in Table 6-16. For films with LA present in PET as a blend, the amorphous films show a small improvement in BIF or a small reduction in oxygen permeability. Upon orientation a larger improvement in BIF was noted with the addition of LA. This indicates that the inclusion of LA into PET acts not only as oxygen scavenger but may also act as a small molecule that affects the microstructure of PET. Results in literature indicate that small molecules blended into PET act as antiplasticizer leading to reduced permeability. This has been attributed chain motion.

Figure 6-13: First heating ramp of DSC to determine degree of crystallinity in oriented

PET film.

150

Table 6-15: Orientation conditions and crystallinity level of blended films.

Temperature of Stretch Ratio Crystallinity orientation (in x in) 26% PET 90 2.5x2.5 (±4%) 27% PET 0.25 B 90 2.5x2.5 (±1%) 30% PET 0.5 B 90 2.5x2.5 (±6%) 30% PET 0.65 B 90 2.5x2.5 (±1%) 34% PET 0.9 B 90 2.5x2.5 (±3%)

180

160 (a) 140

(b) ) 2 120 (c)

100 (d)

t Q 80 (e)

60 CC.mil/(day.100in 40

0 0 5 10 15 20 Time, days

Figure 6-14: Cumulative amount of oxygen permeating through oriented PET and

PET/LA films. (a) PET, (b) PET 0.25 B (c) PET 0.5 B (d) PET 0.65 B and (e) PET 0.9 B at 25oC. 151

Amorphous Oriented Permeability Permeability (cc.mil/100 BIF BIF (cc.mil/100 in2.atm) in2.atm) 10.2 7.7 PET 1 1 (±0.5) (±0.5) 9.2 6.35 PET 0.25 B 1.11 1.16 (±0.4) (±0.4) 8.9 PET 0.5 B 1.14 5.64 1.36 (±0.3) 8.2 1.20 4.6 PET 0.65 B 1.70 (±0.2) (±0.3) 8.7 3.97 PET 0.9 B 1.17 1.80 (±0) (±0.2)

6.2.4.2. Oxygen permeation PET and PET/LA terminated films.

Amorphous

The cumulative oxygen permeated through amorphous PET terminated LA films are shown as function of time in Figure 6-15. It can be noted that the amorphous films with PET terminated LA shows a reduction in oxygen permeability with increase in BIF when compared to PET and their permeability values are shown in Table 6-18.

Interestingly, addition of LA led to progressive decrease in oxygen permeability with increasing LA loading. This was not observed for the blended films. On comparing the 152

results from with blended systems, has lower oxygen permeability the reactive extruded systems. This indicates that the method in which LA was included into PET plays a role in reducing oxygen permeability.

Orientation

The condition at which the films were oriented and the level of crystallinity for

PET terminated LA films are given in Table 6-17. The cumulative oxygen permeating through these films are shown in Figure 6-16. It can be noted that the oriented films with

LA terminated PET shows a sharp reduction in oxygen transport when compared to PET with permeability values are shown in Table 6-17. The 0.5% nominal loading films has a reduction in permeability similar to that obtained from the bottle sidewall with the same nominal loading. Thus to achieve the highest reduction in permeability the sample has to be reactive extruded as compared to blending and oriented to high crystallinity.

153

250

(a) 200

(b)

) 2 150

(c)

t Q

100 CC.mil/(100in

0 0 5 10 15 20 Time, days

Figure 6-15: Cumulative amount of oxygen permeating through amorphous PET and PET terminated LA films. (a) PET, (b) PET 0.11 RE and (c) PET 0.33 RE

154

250

)

2 200

(a)

Q 150 CC.mil/(100in 100 (b)

50 (c)

0 0 10 20 30 Time, days

Figure 6-16: Cumulative amount of oxygen permeating through oriented PET and PET terminated LA films. (a) PET, (b) PET 0.11 RE and (c) PET 0.33 RE

Table 6-17: Orientation conditions and crystallinity level of reactive extruded films.

Temperature Stretch Ratio of Crystallinity (in x in) orientation 28% PET 90 2.5x2.5 (±3%) PET 0.11 RE 26% 90 2.5x2.5 (Nominal loading 0.25%) (±2%) PET 0.33 RE 29% 90 2.5x2.5 (Nominal loading 0.50%) (±3%)

155

Table 6-18: Oxygen Permeability values of PET and PET terminated LA and their Barrier improvement factor

Amorphous Oriented Permeability Permeability BIF BIF (cc.mil/100 in2.atm) (cc.mil/100 in2.atm) 10.2 6.9 PET 1 1 (±0.5) (±0.5) 9.5 5.5 PET 0.11 RE 1.1 1.25 (±0.4) (±0.4) 7.1 3.43 PET 0.33 RE 1.43 2.01 (±0.3) (±0.6)

6.2.5. Confirmation of reaction of Linoleic acid with oxygen

The reaction of C=C of linoleic acid with oxygen can be confirmed from NMR analysis of the films following permeation as shown in Figure 6-17. The figure shows that after oxygen permeation the unsaturated C=C peaks disappear which is indicated by the arrow at 5.4 ppm as well as the peak at 2.8 ppm has disappeared. This is consistent with reaction of C=C with oxygen permeating through PET. The NMR of the bottles sidewall before oxidation described in section 5.11 and for the films are described in section 6.1.1. This is in accordance that LA would slowly react with oxygen permeating through PET estimated using Thiele modulus.

156

0.040 PET+0.25% LOSSE amp.001.001.1r.esp

0.035

0.030

0.025

0.020 (e)

Normalized Intensity 0.015 (d)

0.010 (c)

0.005 (b)

(a) 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 Chemical Shift (ppm) Figure 6-17: NMR spectra of PET/LA systems after oxygen permeation. (a) PET, (b) PET 1sp bottle side wall, (c) PET 2sp bottle, (d) PET 0.9B and (e) PET 0.33RE

These systems do not show a change in time lag during which the oxygen

transmission rate would be zero, is because the rate of oxidation is slow and the time lag

could not be noted as mentioned section 6.2.4.1. In chapter 4 when LA was diluted in

non-reactive oil the rate of oxidation was decreased with lower concentration of LA.

These systems have even greater dilution in the polymer (less than 2%). Thus relatively 157

slow reaction of oxygen with LA takes place which has been shown in constant reduction in oxygen permeation over time. This is also in accordance with Dr. Cameron were slow reaction would show a reaction in oxygen permeability [112].

6.2.6. Potential cases for reduction in oxygen permeation

When PET/LA systems were characterized for their bulk properties in terms of

Tg, Tc which show general reduction relative to PET. The dynamic crystallization studies show that a higher rate of cooling is required to obtain completely amorphous systems all of which have indicated the addition of LA has a plasticizing effect. However, the oxygen permeability through these PET/LA systems exhibited a reduction relative to base PET.

Table 6-19 shows the reduction in oxygen permeability’s when 0.5% nominal loading was added to obtain various forms of PET/LA systems.

158

Table 6-19: Oxygen permeability’s and Barrier improvement factor (BIF) for PET with 0.5% nominal loading of LA

Amorphous Oriented

Permeability Permeability BIF BIF (cc.mil/100 in2.atm) (cc.mil/100 in2.atm)

10.2 6.9 PET* 1 1 (±0.5) (±0.5)

8.9 PET 0.5 B 1.14+ 5.64 1.36+ (±0.3)

7.1 3.43 PET 0.33 RE 1.43 2.01 (±0.3) (±0.6) 3.14 PET/ LA 2sp - - (±0.2) 2.29# (Bottle)

* PET when reactive extruded films were studied (Table 6-18) + Based on the permeability of PET control (Table 6-16) # Based on the permeability of PET control bottle (Table 5-7)

The NMR of the films and bottle sidewall conducted after oxygen permeation has show that LA reacted with oxygen permeating through PET. However, when the oxygen permeability of all the forms were compared there are difference in level of oxygen reductions, these could be due are two factors that can affect the reduction in oxygen permeation:

(1) Chain conformation ( Trans- gauche)

The ethylene glycol chain in PET can have two different confirmation a trans

(extended) or a gauche (relaxed) form [168] in which, the amorphous region of PET has both of these confirmations. The relative amount of trans and gauche conformation have 159

been known to affect the oxygen permeability through PET where higher concentration of trans form leads to reduced oxygen permeability. Note Oxygen cannot permeate through the crystalline regions, so that only the amorphous region allows the gases to permeates [169]. When we consider the blends and reactive extrusion with LA, the reactive extruded films show a greater reduction in oxygen permeation. This could be due the fact that the LA has been attached end of PET which could affect the confirmation of the ethylene chains. This could be a reason as to why a higher reduction in oxygen permeation was noted when PET was terminated LA. When the samples were oriented the crystalline regions would not include LA, hence LA would be present only the amorphous region, thus if more amorphous trans confirmation were present the reduction in oxygen permeation would be higher. There have been cases where copolymers of PET were prepared where the trans confirmation has been known to reduce oxygen permeability [81, 84, 170].

(2) Small molecule effect ( Free volume )

When small molecules are used in PET as antiplasticizer, reduction in thermal properties like Tg, Tc and Tm have been reported which is similar when LA was introduced into PET [27, 77]. When small molecules are added into the PET, the microstructure of the polymer has been determined by studying the β relaxation at temperature below room temperature. This is related to the ethylene glycol chain mobility, and the addition of small molecules would restrict the chain motion of the polymer chains. When LA is present within PET especially in the blends it could affect the local polymer chain motion as antiplasticizer. Inclusion of LA as blend there is a 160

reduction in oxygen permeability and when oriented all the LA are present in the amorphous phase thereby a higher local concentration would be present in the amorphous phase. This higher local concentration could affect the chain motion in the amorphous phase, giving the oriented blends a greater reduction in oxygen permeation [27, 77].

The goal of this work was to understand the effect of LA on the bulk properties

PET and confirm that LA could react with oxygen within the PET. The results indicates that further understanding into the microstructure of PET and the interaction of LA on the chain motion and confirmation of the polymer chain have to be looked into as well.

6.3. Conclusion

Linoleic acid was incorporated into PET using single and twin screw extruder to form PET/LA as blends and reactive extruded samples. The single screw process produced blends which was confirmed with NMR which showed that no reaction took place and end group analysis showed that the hydroxyl end group do not change with increase in carboxyl end group which confirm that Linoleic acid is present in the form of blends. TGA has also confirmed the blended systems and confirms when single screw extrusion was conducted blends are only prepared. Reactive extrusion was conducted with the twin screw extruder to make pellets which were made into sheets using the single screw extruder, from the blends it was confirmed that no reaction takes place while sheets are made. The reaction was confirmed using NMR and end group analysis which not all of nominal loading got reacted, which was confirmed with TGA which shows some weight loss which is due to unbound LA. The density of the films was nearly the same and the free volume that was calculated showed no effect on the free volume when 161

LA was added into PET in both cases. The Thermal transition show a reduction in Tg and

Tc, hence a dynamic cooling study was conducted which showed that the addition of LA increased the rate of crystallization which has been confirmed by non-isothermal crystallization studies. The intrinsic viscosity of the samples were determined using solution and melt approaches, were melt IV of blends does not give the actual IV of the

PET/LA blends as LA has a plasticizing effect on PET. The solution method was not affected by the presence of LA thus gives the actual IV of the PET/LA blends. The reactive extruded pellets when analyzed using solution and melt methods has given the same IV values. The films of blended and reactive extruded films were analyzed for the amount of oxygen permeation through them showed that the reduction was better when reactive was used these films were amorphous in nature. The amorphous films were stretched using LET to obtain oriented films and their crystallinity in these films were around 30%. When oxygen permeation was conducted on the oriented films there was an improvement when compared to the amorphous films, but the reactive extruded films showed the best results for a nominal loading of 0.5%. This shows that the reduction which was obtained for the bottle systems were due to reactive extrusion orientation

162

Chapter 7

7. Conclusion

This work was geared towards identifying a bio based oxygen scavenger that can

react with oxygen permeating through PET. The work has three distinct parts (1)

selection of a bio based oxygen scavenger Chapter 4 (2) Methods of inclusion of oxygen

scavenger into PET Chapter 3 (3) the effects of inclusion of oxygen scavenger had on the

bulk properties of PET Chapters 5 and 6.

Three unsaturated fatty acids were chosen as potential oxygen scavenger for PET

- oleic, linoleic and linolenic acids. The reactivity of oleic, linoleic acid and linolenic

acids with oxygen were studied at 25oC in pressure decay cell, using 0.5 ml of OS and an

initial pressure of 20 psi without a catalyst a detailed description can be found in 4.1.

Linoleic and linolenic acids reacted with oxygen but the reactions of oleic acid with

oxygen under without catalyst were very slow and low. Linoleic acid (LA) utilized most

of the oxygen scavenging capacity, while linolenic acid utilized only about 50% of its

oxygen scavenging capacity. The oxygen scavenging capacities of these compounds were

163

monitored with cobalt acetate as the catalyst. The improvement in the scavenging capacity was marked when oleic acid was a scavenger showing 90% of scavenger utilization. However in the case of linoleic and linolenic acid the improvement in the scavenger utilization in the presence of catalyst was not appreciable. Since LA reacted rapidly with oxygen and almost completely utilized the C=C even in the absence of catalyst was chosen for introduction into PET.

Since the oxygen scavenger capacities were determined in a high pressure system, the changes in structure of the OS scavenger were not studied. A low pressure system was used to collect the sample at different times to understand the change in structure of

OS. The oxidation process followed a free radical mechanism as verified by FTIR spectra where a hydroxyl peak was formed and the C=C peak of LA decreased over time, peaks due to peroxide formation were also noted. This is consistent with other scavengers reported in literature with unsaturated groups [13, 68]. Upon drying of the samples that had undergone oxidation, the FTIR spectra indicated that the hydroxyl peak decreases over time which is consistent with water being formed.

The kinetics was determined using a high pressure setup at, during the initial time period the rate of reaction followed a pseudo first order reaction model. The kinetics of oleic, linoleic and linolenic acid with and without catalyst were determined and compared with the other oxygen scavengers in terms of their apparent rate constant. The apparent rate constant of linoleic and linolenic acid in the presence of cobalt as catalyst were 0.4 and 0.45 day-1, which when compared with literature was higher than oxygen scavengers 164

with one unsaturated carbon site, but when compared with polybuatdiene it was lower which had multiple unsaturated carbon sites. This is consistent with free radical oxygen scavenging mechanism.

As the LA would be diluted in the polymer, the effect of dilution of LA on reaction kinetics in a non-reactive medium was monitored. LA was diluted in hexanoic acid, which did not react with oxygen. Dilution of LA from 10 to 75% was used for kinetics studies. The kinetics of the LA decreased with lower concentration of LA in the systems as expected. This reveals that LA when introduced into PET at low concentration

(<2%) would have low oxidation kinetics. The Thiele modulus, was used to determine if reaction with oxygen or oxygen diffusion through PET had a dominating effect on reaction. The Thiele modulus for pure linoleic acid was 0.55 which indicated that the systems would be slowly reacting system related to oxygen diffusion.

Linoleic acid was incorporated into PET using two different methods namely two stage and single stage process as described in Chapter 3 (3.2.2). The aim of the two stage process was to achieve PET terminated with LA and the single stage process to obtain blends of PET/LA. Bottles and films were prepared using these two approaches. The preparations of bottles are described in 3.2.3 with all the bottles prepared using 0.5 wt% nominal loading of LA. Films were using the single stage process, the loading were varied between 0.25 to 2 wt % nominal loadings. Two stage pellets were prepared with nominal loading of LA between 0.25 and 2 wt%, but films were achieved only for 0.25 and 0.5wt % nominal loading due to plasticizing and degradation that resulted in low 165

melt IV. The presence of linoleic acid within PET was confirmed by NMR, where C=C were observed in the spectra along with the methyl peak of LA. The reaction with the hydroxyl end group of PET and carboxyl end group of LA was also confirmed with

NMR. NMR could not be used to quantify the extent of reaction so end group analysis of bottle sidewalls and films that were prepared. There was no reaction taking place in single stage films but the two stage pellets showed reaction taking place between the end groups. The single stage process bottle also showed reaction between the end groups. The end group analyses on the bottle sidewall and films confirmed the NMR results that the single stage process bottles had partial reaction taking place.

End group analyses conducted on the single stage films showed that the hydroxyl end group does not change with an increase in carboxyl end group which confirm that linoleic acid is present in the form of blends. The two stage films showed a decrease in hydroxyl end groups which is indicative that reaction between the end groups has taken place. The single stage bottle showed some of the LA was bound to PET and there was some unbound LA. However, the reactive extrusion followed by injection molding lead to full reaction during the two stage process of bottles.

Extraction of LA from the PET were studied using chloroform- D extraction, the two stage process showed no LA in the extract indicating that it was bound to the PET as end group. The single stage process showed the presence of LA in the extract indicating that some of the LA was in an unbound form. TGA was also used to verify the quantity of unbound LA with the PET, which confirmed that as each processing stage was completed the amount of unbound LA was reduced. Based on the TGA and end group 166

analysis, the amount of unbound and bound LA present in each PET/LA sample were determined.

The densities of the films (single and two stage) were nearly the same and there was no effect on the free volume when LA was added to PET in all cases. There was a reduction in Tg and Tc with inclusion of LA, hence a dynamic cooling study was conducted that showed that the addition of LA increases the rate of crystallization. The intrinsic viscosity of the samples were determined using solution and melt approaches, were melt IV of blends does not give the actual IV of the PET/LA blends as LA has a plasticizing effect on PET. The solution IV was not affected by the presence of LA thus provides the true IV of the PET/LA blends. The reactive extruded pellets when analyzed using solution and melt methods gave the same IV values. The mechanical strength of these bottles was similar to that of PET. The optical clarity of the sidewall and films determined by haze analysis indicated that there was little effect on haze in all cases.

The oxygen permeability of the bottle side wall showed that addition of LA of

0.5% using the two stage process reduced the permeability by 56% while in the case of the single stage process the reduction was 51%. The impact of LA loading and the method of incorporation of LA (blend verses reaction) were conducted on amorphous films which showed that reaction of end group give a higher reduction in oxygen permeability. When bottles are prepared they undergo an orientation process. This can be replicated on the films to obtain the same level of crystallinity as oriented bottles following the method explained in 3.2.4. The permeation through the oriented sample 167

showed a higher reduction of oxygen permeation than their amorphous counterparts. The reactive extruded films had lowest permeability. Thus reaction with the end group followed by orientation has led to decrease in oxygen permeability’s in the bottles. NMR showed the unsaturated carbon bonds have disappeared after oxidation which show that

LA acted an oxygen scavenger.

The reduction on the oxygen permeability by the addition LA in various forms could have an effect on the free volume and microstructure of PET. To better understand the reduction in oxygen permeability further investigation on these types of systems have to conducted when the free volume of the PET/LA systems have to be determined using

DMA or positron analyses. The diffusion and solubility coefficient of oxygen through the

PET/LA would also help understand the why these reduction have taken place. The fraction of trans and gauche confirmation which has been linked to reduction in oxygen permeability would give an understanding on the reduction of oxygen permeability.

168

Chapter 8

8. Future Work

8.1. Microstructure of PET/oxygen scavenger systems

The current work utilized LA which has behaved like an oxygen scavenger, but

has resulted in only a reduction in permeability of oxygen over time. This has led to

understanding the microstructure of the PET/LA systems. There are various approaches

in the literature in understand the microstructure of polymer. Free volume of polymer and

the distribution of free volume, positron annihilation can be used to determine the free

volume distribution. This would give information about the major distributions of free

volume, as even small change in free volume could impact the oxygen permeating

through a polymer.

The ethylene glycol chain relaxation can be determined using Dynamic

mechanical analysis (DMA) at temperature below room temperature. This relaxation is

referred to as β transition which occurs at -75oC for PET. There have studies where

copolymers are produced which have reduced the oxygen permeability and the reduction

has been related to on the relaxation of PET by the addition on a new monomer. The

fraction of trans and gauche confirmation would also be useful to understand these 169

reduction that were obtained. The trans concentration can be varied by various levels of orientation to understand the how the fraction of trans would affect then oxygen permeability.

In this study the permeability was determined directly, Permeability has two components which are diffusivity and solubility. The solubility of the oxygen through the polymer a can be determined using a gas sorption step up as shown in figure 8-1. These further analyses could give a better understanding on the reduction observed using the LA into

PET.

Pressure transducer Reservoir Cell Sample cell

Gas inlet Polymer

Figure 8-1: Oxygen Sorption Setup, to determined solubility coefficient of the polymer

8.2. Potential oxygen scavengers

The current work utilized a bio based unsaturated fatty acid that has shown the potential to react with oxygen. There are other natural antioxidants in the form of carotenoids that

170

can be studied as potential oxygen scavengers. Carotenoids are present in vegetable and fruits grains like oats, wheat’s and cereals. Some of the carotenoids that of interest are cryptoxanthin, lutein the structures of these molecules are shown in Figure 8-3.

Cryptoxanthin has only one functional end group but lutein has two functional end group and there 9 unsaturated C=C in their structure than can be used to react them with PET.

Using these antioxidants would impart color into the polymer but have the capability to react with oxygen their rate and capacity has to be explored.

Figure 8-2: β- cryptoxanthin

Figure 8-3: Lutein

171

8.3. Linoleic acid as catalyst

Linoleic acid can react with oxygen without the use of a catalyst, which has been studied in this work and oleic acid required a catalyst for oxidation of oleic acid takes place.

Some preliminary work was conducted by blending linoleic and oleic acid. Figure 8-3 shows that a mixture of (a) linoleic and oleic acids and (b) linoleic and hexanioc acid, in both cases the fraction of LA was present in 10% by volume. It can be noted from Figure

8-3 that when oleic acid was present a higher pressure drop was observed than with only linoleic acid in the mixture. This excess pressure drop is due to oleic acid, but also shows that LA could work as catalyst which would enable oleic acid to react with oxygen. This could be extended for polybutadiene and MXD6 systems which require a metal catalyst to react with oxygen. These could be future direction that could be taken to study new oxygen scavenger within polymer or to use these fatty acid to replace the metal catalyst in polymer systems.

172

10 9

8 (a) 7 6 5 4 (b) 3 Pressure psi Drop, Pressure 2 1 0 0 5 10 15 20 25 30 35 Time, days

Figure 8-4: Linoleic acid mixed with oleic and hexaionic acid (10% Linoleic acid was present in the mixture) (a) Linoleic acid/ oleic acid (b) Linoleic acid/ hexaionic acid.

173

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Appendix

Table A-1: Oxygen scavenger studied using linolenic acid (0.5 ml) at 25oC and an initial pressure of 20 psi

Moles O2 sorbed/ Moles O2 sorbed/ Moles O2 sorbed/ Moles of Moles of Linolenic Moles of Linolenic Time Linolenic acid Time acid Time acid 0.000 0.000 8.975 1.448 25.057 1.513 0.042 0.008 9.058 1.448 26.057 1.518 0.083 0.004 9.142 1.456 27.047 1.519 0.125 0.008 9.867 1.458 27.203 1.519 0.292 0.036 9.925 1.453 0.917 0.415 9.961 1.457 1.979 0.870 10.040 1.450 2.854 1.082 10.128 1.454 2.896 1.092 10.187 1.450 3.076 1.121 10.831 1.460 3.190 1.139 11.003 1.458 3.232 1.144 11.044 1.457 3.815 1.227 11.086 1.456 3.919 1.240 11.128 1.456 4.072 1.254 11.867 1.485 4.131 1.257 11.930 1.491 4.172 1.262 11.961 1.487 4.846 1.320 12.044 1.480 4.888 1.329 12.211 1.485 4.929 1.330 12.867 1.479 4.971 1.328 12.925 1.485 5.013 1.331 13.071 1.479 5.054 1.334 13.238 1.481 5.096 1.334 13.272 1.482 5.169 1.340 14.029 1.487 5.867 1.377 14.238 1.487 5.929 1.377 14.925 1.489 5.950 1.380 15.231 1.501 5.992 1.380 16.890 1.519 6.117 1.387 16.932 1.519 195

6.158 1.382 17.057 1.513 6.200 1.383 17.124 1.507 6.815 1.415 17.988 1.501 6.898 1.417 18.071 1.505 6.950 1.411 18.911 1.509 6.981 1.418 19.071 1.510 7.082 1.418 19.935 1.524 7.124 1.421 20.015 1.525 7.161 1.418 20.153 1.514 7.274 1.420 20.892 1.517 7.913 1.435 20.949 1.517 8.020 1.437 22.015 1.510 8.159 1.440 24.057 1.517

Table A-2: Oxygen scavenger studied using linoleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi

Moles O2 sorbed/ Moles O2 sorbed/ Moles O2 sorbed/ Moles of Linoleic Moles of Linoleic Moles of Linoleic Time acid Time acid Time acid 0.000 0.000 3.044 1.275 14.272 1.718 0.000 0.039 3.094 1.288 14.308 1.716 0.011 0.059 3.122 1.276 14.975 1.745 0.022 0.094 3.184 1.279 15.083 1.746 0.037 0.140 3.263 1.289 15.215 1.758 0.058 0.222 3.992 1.374 15.254 1.762 0.078 0.300 4.064 1.357 15.306 1.764 0.110 0.406 4.145 1.373 15.413 1.771 0.152 0.468 5.030 1.446 15.469 1.768 0.212 0.572 5.356 1.465 15.969 1.781 0.249 0.631 5.419 1.458 16.063 1.781 0.294 0.675 5.944 1.500 16.149 1.780 0.335 0.745 5.978 1.495 16.231 1.776 0.351 0.744 6.072 1.508 16.288 1.780 0.413 0.776 6.153 1.498 16.493 1.791 0.454 0.806 6.327 1.509 16.971 1.808 0.496 0.824 6.382 1.516 17.087 1.798 0.936 0.965 6.431 1.515 18.018 1.808 0.976 0.982 6.930 1.529 18.102 1.806 0.999 0.977 7.026 1.531 19.027 1.805 1.016 1.004 7.111 1.521 19.980 1.814 1.078 0.993 7.183 1.516 20.094 1.801 1.119 1.027 7.274 1.536 20.306 1.805 196

1.160 1.013 7.359 1.538 20.960 1.825 1.217 1.021 7.479 1.524 21.082 1.831 1.250 1.040 7.956 1.544 21.167 1.826 1.333 1.045 8.038 1.556 21.274 1.829 1.381 1.055 8.121 1.557 21.971 1.843 1.413 1.060 8.240 1.559 22.087 1.844 1.455 1.095 8.331 1.574 22.213 1.850 1.496 1.078 8.899 1.576 22.976 1.877 1.972 1.167 9.013 1.585 23.199 1.866 2.001 1.160 9.076 1.597 22.869 1.877 2.039 1.181 9.397 1.622 23.951 1.874 2.081 1.170 9.485 1.626 24.083 1.866 2.131 1.195 9.933 1.628 24.169 1.866 2.165 1.197 10.040 1.630 24.255 1.865 2.207 1.185 10.150 1.633 25.259 1.885 2.272 1.202 10.227 1.636 26.949 1.911 2.324 1.210 11.227 1.662 27.326 1.882 2.415 1.213 12.994 1.709 28.289 1.908 2.885 1.253 13.186 1.716 28.958 1.914 2.913 1.277 14.086 1.737

Table A-3: Oxygen scavenger studied using oleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi

Moles O2 sorbed/ Moles O2 sorbed/ Moles of Linolenic Time Moles of oleic acid Time acid 0 0 8.945139 0.046447 0.007639 0 11.94514 0.046447 0.004167 0.009289 12.94514 0.065026 0.011111 0 13.94514 0.065026 0.018056 0 14.94514 0.055737 0.025 0 15.94514 0.046447 0.031944 0 18.94514 0.092895 0.038889 0 19.94514 0.102184 0.045833 0 20.94514 0.111474 0.052778 0.009289 26.93472 0.130053 0.059722 0.009289 27.93472 0.139342 0.068056 0.009289 28.93472 0.1765 0.075 0 29.93472 0.1765 0.080556 0.009289 33.93472 0.195079

197

0.099306 0.018579 34.93472 0.222948 0.110417 0 35.93472 0.222948 0.120833 0.018579 0.129167 0.009289 0.139583 0.009289 0.15 0.009289 0.193056 0.018579 0.233333 0.009289 0.275 0.018579 0.316667 0.018579 0.358333 0.018579 0.934722 0.009289 1.961111 0.018579 3.052083 0.009289 4.945139 0.046447 5.941667 0.046447 6.945139 0.037158 7.945139 0.046447

Table A-4: Oxygen scavenger studied using linolenic acid (0.5 ml) at 25oC and an initial pressure of 20 psi with cobalt as catalyst Moles O2 sorbed/ Moles of Linolenic Time acid 0 0 0.0625 0.229589 0.083333 0.293874 0.166667 0.440811 0.3125 0.551013 0.979167 0.771419 1.03125 0.780602 1.104167 0.79897 1.166667 0.808153 1.28125 0.817337 1.322917 0.835704 2.125 0.918356 2.166667 0.927539 2.416667 0.936723 3.041667 0.973457 4.104167 1.056109 4.979167 1.120394 5.020833 1.129578 198

5.201389 1.138761 5.356944 1.147945 5.940278 1.175495 6.255556 1.184679 6.970833 1.21223 7.0125 1.221413 7.991667 1.23978 8.054167 1.258147 8.939583 1.276514 9.286111 1.285698 10.0375 1.294882 10.28403 1.304065 11.1 1.313249 12.08611 1.322432 13.12778 1.331616 13.16944 1.340799 13.99236 1.349983 14.05486 1.359167 20.1125 1.36835 22.13958 1.377534 23.01736 1.386717

199

Table A-5: Oxygen scavenger studied using linoleic acid (0.5 ml) at 25oC and an initial pressure of 20 psi with cobalt as catalyst

Moles O2 Moles O2 Moles O2 sorbed/ Moles sorbed/ Moles sorbed/ Moles of Time of Linoleic acid Time of Linoleic acid Time Linoleic acid 0 0 5.427083 1.035877 15.97708 1.530485 0.040972 0.018664 5.952778 1.119867 16.07083 1.521153 0.056944 0.037329 5.986806 1.119867 16.15694 1.521153 0.118056 0.027997 6.080556 1.119867 16.50139 1.530485 0.159722 0.037329 6.161806 1.119867 16.97917 1.539817 0.201389 0.037329 6.335417 1.129199 17.09514 1.539817 0.641667 0.065326 6.390278 1.119867 18.02639 1.558482 0.68125 0.074658 6.438889 1.157196 18.11042 1.567814 0.704167 0.093322 6.938194 1.185193 19.03542 1.567814 0.721528 0.102654 7.034028 1.166528 19.98819 1.567814 0.783333 0.111987 7.119444 1.157196 20.10278 1.567814 0.825 0.139983 7.190972 1.185193 20.31389 1.567814 0.865278 0.139983 7.282639 1.185193 20.96875 1.577146 0.922917 0.139983 7.367361 1.17586 21.09028 1.586478 0.955556 0.16798 7.4875 1.185193 21.17569 1.586478 1.038194 0.177312 7.964583 1.213189 21.28264 1.595811 1.086111 0.195977 8.045833 1.241186 21.97917 1.623807 1.11875 0.195977 8.129167 1.222522 22.09514 1.623807 1.160417 0.223973 8.248611 1.250518 22.22153 1.623807 1.201389 0.205309 8.338889 1.250518 22.98472 1.642472 1.677778 0.382621 8.906944 1.269183 23.20764 1.633139 1.70625 0.382621 9.021528 1.287847 22.87778 1.633139 1.744444 0.382621 9.084028 1.297179 23.95903 1.633139 1.786111 0.391953 9.21875 1.287847 24.09097 1.623807 1.836111 0.410618 9.326389 1.287847 24.17778 1.633139 1.870833 0.401286 9.405556 1.306512 24.26319 1.633139 1.9125 0.429282 9.49375 1.325176 24.99167 1.642472 1.977778 0.475943 9.940972 1.334508 25.11458 1.642472 2.029167 0.466611 10.04792 1.34384 25.21806 1.642472 2.120139 0.494608 10.15833 1.353173 25.26736 1.642472 2.893056 0.606595 10.23542 1.362505 26.32639 1.670468 2.920833 0.625259 11.23542 1.381169 26.95764 1.670468 3.052778 0.634591 13.00208 1.437163 27.01875 1.651804 3.102083 0.681252 13.0875 1.455827 27.11389 1.651804 3.129861 0.681252 13.19444 1.465159 27.33472 1.651804 3.192361 0.699917 13.27014 1.455827 28.18681 1.661136

200

3.270833 0.709249 14.01458 1.483824 28.29722 1.661136 4 0.849233 14.09444 1.474492 28.96667 1.661136 4.072222 0.849233 14.18125 1.465159 29.22917 1.679801 4.153472 0.858565 14.28056 1.474492 32.08889 1.717129 5.038194 1.00788 14.31667 1.483824 32.47708 1.717129 5.364583 1.017213 14.98333 1.502488 35.05347 1.726462

Table A-6: Kinetics study of linoleic acid ( Figure 4-7)

Time - Ln(Ca/Cao) 0 0 0.077083 0.015074 0.1125 0.023997 0.209722 0.036215 0.247917 0.043264

0.289583 0.051849 0.647222 0.127797 0.704861 0.141036 0.742361 0.149195 0.788194 0.159405 0.822222 0.16805 0.866667 0.17677 0.911111 0.186587 0.954167 0.195815 0.994444 0.204435

1.039583 0.21383 1.296528 0.266953 1.650694 0.332067 1.692361 0.339571 1.747917 0.34873 1.836806 0.363643 1.932639 0.37837 1.993056 0.387062 2.032639 0.392898

201

Table A-7: Kinetics study of linoleic acid diluted in heaxanic acid ( Figure 4-8 (a))

Time - Ln(Ca/Cao) 0.000 0.00 0.014 0.33 0.083 1.98 0.000 0.00 0.735 17.65

0.767 18.40 0.787 18.88 0.848 20.35 0.975 23.40 1.041 24.98 1.136 27.27 1.164 27.93 1.503 36.07 1.526 36.63 1.609 38.62 Table A-8: Kinetics study of linoleic acid diluted in 1.639 39.33 heaxanic acid ( Figure 4-8 (b)) 1.810 43.45 1.854 44.50 Time - Ln(Ca/Cao) 1.913 45.92 0.000 0.00 2.035 48.83 0.035 0.83 0.080 1.92 0.132 3.17 0.170 4.08

0.222 5.33 0.253 6.08 0.281 6.75 0.427 10.25 0.962 23.08 1.007 24.17 1.156 27.75 1.201 28.83 1.240 29.75 1.291 30.98

1.983 47.58 2.042 49.00 2.067 49.62 2.087 50.08 2.133 51.20 2.203 52.87 2.241 53.78 2.276 54.63 202

Table A-9: Kinetics study of linoleic acid diluted in heaxanic acid ( Figure 4-8 (c))

Time - Ln(Ca/Cao) 0.000 0.00 0.086 2.07 1.740 41.75 1.777 42.65 1.822 43.73 1.860 44.65

1.881 45.15 1.909 45.82 2.006 48.15 0.000 0.00 0.086 2.07

1.740 41.75 1.777 42.65

1.822 43.73

1.860 44.65 1.881 45.15 1.909 45.82 2.006 48.15

203

Table A-10: Oxygen permeation studies on PET bottles

PET bottles

Day OTR Qt Permeance Permiability CC/m2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 3.629325 46.09243 3.65E-05 3.028501 2 3.992258 96.7941 4.01E-05 3.328006 3 5.141544 162.0917 5.17E-05 4.294693 4 6.169853 240.4488 6.19E-05 5.138124 5 7.016695 329.5609 7.04E-05 5.843356 6 7.500605 424.8185 7.57E-05 6.284165 7 6.835229 511.6259 6.89E-05 5.720926 8 6.835229 598.4334 6.91E-05 5.738279 9 6.835229 685.2408 6.91E-05 5.738279 10 9.6782 808.1539 9.74E-05 8.084127 11 10.28309 938.7491 0.000103 8.580753 12 10.28309 1069.344 0.000104 8.598035 13 10.28309 1199.94 0.000103 8.589385 14 10.28309 1330.535 0.000103 8.537849 15 10.28309 1461.13 0.000103 8.554959 16 10.28309 1591.725 0.000103 8.589385 17 10.28309 1722.32 0.000104 8.650303 18 10.88798 1860.598 0.00011 9.103802 19 6.653763 1945.1 6.65E-05 5.52449 20 9.073313 2060.332 9.09E-05 7.548493 21 9.073313 2175.563 9.06E-05 7.518359 22 9.073313 2290.794 9.09E-05 7.548493 23 9.073313 2406.025 9.09E-05 7.548493 24 9.073313 2521.256 9.12E-05 7.571252 25 9.073313 2636.487 9.11E-05 7.563651 26 9.073313 2751.718 9.07E-05 7.533396 27 9.073313 2866.949 9.19E-05 7.63262 28 9.6782 2989.862 9.86E-05 8.182915 29 10.04113 3117.385 0.000101 8.345304 30 11.00895 3257.198 0.00011 9.104104

204

31 9.315268 3375.502 9.26E-05 7.688158 32 9.315268 3493.806 9.28E-05 7.703473 33 8.347448 3599.819 8.34E-05 6.923801 34 9.980644 3726.573 9.96E-05 8.270195 35 10.04113 3854.095 0.000101 8.353666 36 9.19429 3970.863 9.26E-05 7.687655 37 9.073313 4086.094 9.16E-05 7.601812 38 7.621583 4182.888 7.67E-05 6.36625 39 7.621583 4279.682 7.67E-05 6.36625 40 7.621583 4376.476 7.67E-05 6.36625

205

Table A-11: Oxygen permeation studies on PET 1sp bottles

PET 1 sp bottles

Day OTR Qt Permeance Permiability CC/m2 CC.mil/m2 cc/(day.m2) cc.mil/(100 in2.day.atm)

1 5.59953 57.32519 5.65E-05 3.718908 2 5.798279 116.6851 5.89E-05 3.872566 3 6.70561 185.3337 6.8E-05 4.476102 4 5.003284 236.5549 5.06E-05 3.33058 5 6.757458 305.7343 6.78E-05 4.46092 6 3.119491 337.6701 3.14E-05 2.063425 7 4.026823 378.8947 4.07E-05 2.679052 8 7.05126 451.082 7.11E-05 4.677591 9 5.539041 507.7879 5.56E-05 3.658347 10 6.619198 575.552 6.65E-05 4.371753 11 6.619198 643.316 6.65E-05 4.371753 12 7.483323 719.9265 7.56E-05 4.973034 13 4.890948 769.9976 4.94E-05 3.252081 14 4.890948 820.0687 4.95E-05 3.256591 15 4.1478 862.5318 4.19E-05 2.755637 16 4.847741 912.1605 4.88E-05 3.208338 17 4.925513 962.5855 4.95E-05 3.253263 18 4.97736 1013.541 4.99E-05 3.284211 19 4.821818 1062.905 4.86E-05 3.194395 20 4.787253 1111.914 4.84E-05 3.186579 21 5.063773 1163.754 5.14E-05 3.383136 22 4.044105 1205.156 4.1E-05 2.69431 23 4.97736 1256.112 5.01E-05 3.294123 24 5.150185 1308.837 5.15E-05 3.388051 25 5.32301 1363.331 5.32E-05 3.501744 26 5.063773 1415.171 5.1E-05 3.358069 27 5.063773 1467.012 5.15E-05 3.388814 28 4.545298 1513.544 4.64E-05 3.051148 29 4.545298 1560.077 4.6E-05 3.026443 30 4.890948 1610.148 4.91E-05 3.227193 31 5.037849 1661.723 5.04E-05 3.314151 32 6.472296 1727.983 6.5E-05 4.274902 206

33 5.495835 1784.246 5.56E-05 3.659349 34 5.564965 1841.218 5.64E-05 3.709133 35 4.890948 1891.289 4.96E-05 3.263196 36 4.804535 1940.475 4.85E-05 3.189369 37 6.057516 2002.489 6.09E-05 4.004964 38 5.513118 2058.93 5.52E-05 3.630437 39 5.409423 2114.309 5.43E-05 3.572882 40 5.124261 2166.768 5.65E-05 3.718908

207

Table A-12: Oxygen permeation studies on PET 2sp bottles

PET 2 sp bottles

Day OTR Qt Permeance Permiability CC/m2 CC.mil/m2 cc/(day.m2) cc.mil/(100 in2.day.atm)

1 2.97259 34.7793 3.00231E-05 2.296482 2 2.022053 58.43732 2.05201E-05 1.569593 3 3.421935 98.47396 3.47524E-05 2.658227 4 3.421935 138.5106 3.46294E-05 2.648815 5 4.381114 189.7696 4.395E-05 3.361756 6 4.381114 241.0287 4.40623E-05 3.370343 7 4.208289 290.2656 4.2588E-05 3.257573 8 4.208289 339.5026 4.23795E-05 3.241629 9 4.381114 390.7616 4.3995E-05 3.365199 10 4.381114 442.0207 4.3995E-05 3.365199 11 4.381114 493.2797 4.3995E-05 3.365199 12 4.381114 544.5387 4.42188E-05 3.382317 13 3.862639 589.7316 3.9041E-05 2.986263 14 3.862639 634.9245 3.90517E-05 2.987078 15 3.862639 680.1174 3.90229E-05 2.984875 16 2.808406 712.9757 2.82536E-05 2.161129 17 3.084926 749.0693 3.09732E-05 2.36915 18 3.413294 789.0049 3.42597E-05 2.620539 19 3.620684 831.3669 3.64474E-05 2.787876 20 3.881217 876.7771 3.9224E-05 3.000262 21 3.033079 912.2642 3.08199E-05 2.357427 22 3.214545 949.8743 3.25589E-05 2.490448 23 3.568836 991.6297 3.59762E-05 2.751833 24 3.681173 1034.699 3.68117E-05 2.815744 25 4.070029 1082.319 4.07003E-05 3.113182 26 3.266393 1120.536 3.28942E-05 2.51609 27 2.929384 1154.809 2.98004E-05 2.279449 28 2.912101 1188.881 2.97153E-05 2.272937 29 3.04172 1224.469 3.07866E-05 2.354883 30 3.231828 1262.281 3.24481E-05 2.481966 31 3.344164 1301.408 3.34416E-05 2.557965 32 4.121876 1349.634 4.13843E-05 3.165503 208

33 3.983616 1396.242 4.04018E-05 3.09035 34 4.087311 1444.064 4.13695E-05 3.164374 35 3.551554 1485.617 3.60564E-05 2.757968 36 3.577478 1527.474 3.60997E-05 2.761279 37 4.121876 1575.7 4.13843E-05 3.165503 38 3.992258 1622.409 3.99226E-05 3.053695 39 3.819433 1667.096 3.83477E-05 2.933233 40 2.97259 1705.313 3.28281E-05 2.511033

209

Table A-13: Oxygen permeation studies on PET SSE control amorphous film

PET SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 4.68 9.36 4.71E-05 9.53 2 4.98 19.32 4.97E-05 10.07206 3 5.04 29.4 5.03E-05 10.19341 4 5.49 40.38 5.46E-05 11.06489 5 5.04 50.46 5.01E-05 10.15793 6 5.04 60.54 5.01E-05 10.15793 7 5.04 70.62 5.01E-05 10.15793 8 5.04 80.7 5.01E-05 10.15793 9 5.04 90.78 5.01E-05 10.15793 10 5.04 100.86 5.01E-05 10.15793 11 5.04 110.94 5.04E-05 10.21533 12 5.04 121.02 5.04E-05 10.21533 13 5.04 131.1 5.04E-05 10.21533 14 5.04 141.18 5.04E-05 10.21533 15 5.04 151.26 5.04E-05 10.21533 16 5.04 161.34 5.04E-05 10.21533 17 5.04 171.42 5.04E-05 10.21533 18 5.04 181.5 5.04E-05 10.21533 19 5.04 191.58 5.04E-05 10.21533 20 5.04 201.66 5.04E-05 10.21533 21 5.04 211.74 5.04E-05 10.21533 22 5.04 221.82 5.04E-05 10.21533 23 5.04 231.9 5.04E-05 10.21533 24 5.04 241.98 5.04E-05 10.21533 25 5.04 252.06 5.04E-05 10.21533 26 5.04 262.14 5.04E-05 10.21533 27 5.04 272.22 5.04E-05 10.21533 28 5.04 282.3 5.04E-05 10.21533 29 5.04 292.38 5.04E-05 10.21533 30 5.04 302.46 5.04E-05 10.21533

210

Table A-14 Oxygen permeation studies on PET +0.25 LA SSE amorphous film

PET+ 0.25 % SSE amorphous

Day OTR Qt Permeance Permeability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 7.595 9.548 7.6E-05 9.68423 2 7.455 18.92 7.46E-05 9.504577 3 7.42 28.248 7.45E-05 9.489683 4 7.49 37.664 7.5E-05 9.553502 5 7.28 46.816 7.27E-05 9.259871 6 7.28 55.968 7.31E-05 9.310445 7 7.315 65.164 7.39E-05 9.411523 8 7.35 74.404 7.41E-05 9.442058 9 7.245 83.512 7.28E-05 9.279472 10 7.525 92.972 7.55E-05 9.6148 11 7.455 102.344 7.46E-05 9.496688 12 7.385 111.628 7.41E-05 9.440844 13 8.155 121.88 8.21E-05 10.45773 14 7.7 131.56 7.72E-05 9.838696 15 7.245 140.668 7.26E-05 9.244337 16 7.315 149.864 7.39E-05 9.414851 17 7.21 158.928 7.31E-05 9.307735 18 7.595 168.476 7.6E-05 9.68423 19 7.455 177.848 7.46E-05 9.504577 20 7.42 187.176 7.45E-05 9.489683 21 7.49 196.592 7.5E-05 9.553502 22 7.28 205.744 7.27E-05 9.259871 23 7.28 214.896 7.31E-05 9.310445 24 7.315 224.092 7.39E-05 9.411523 25 7.35 233.332 7.41E-05 9.442058 26 7.245 242.44 7.28E-05 9.279472 27 7.525 251.9 7.55E-05 9.6148 28 7.455 261.272 7.46E-05 9.496688 29 7.385 270.556 7.41E-05 9.440844 30 8.155 280.808 8.21E-05 10.45773

211

Table A-15: Oxygen permeation studies on PET +0.5 LA SSE amorphous film

PET + 0.5 SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 6 10.05 6.06956E-05 10.30146 2 5.616 19.4568 5.68484E-05 9.648508 3 5.832 29.2254 5.83801E-05 9.908473 4 5.712 38.793 5.71789E-05 9.704595 5 5.712 48.3606 5.71789E-05 9.704595 6 5.712 57.9282 5.71789E-05 9.704595 7 5.712 67.4958 5.71789E-05 9.704595 8 5.712 77.0634 5.71789E-05 9.704595 9 4.632 84.822 4.57893E-05 7.771515 10 4.68 92.661 4.65301E-05 7.89725 11 5.16 101.304 5.17584E-05 8.784607 12 4.632 109.0626 4.69044E-05 7.960778 13 5.208 117.786 5.27815E-05 8.958249 14 5.184 126.4692 5.25382E-05 8.916966 15 5.208 135.1926 5.23733E-05 8.888972 16 5.256 143.9964 5.34483E-05 9.071428 17 5.208 152.7198 5.23081E-05 8.877901 18 5.208 161.4432 5.27815E-05 8.958249 19 5.736 171.051 5.81326E-05 9.866458 20 4.632 178.8096 4.69439E-05 7.967475 21 4.68 186.6486 4.74303E-05 8.050039 22 5.136 195.2514 5.20518E-05 8.834402 23 4.584 202.9296 4.64574E-05 7.88491 24 5.208 211.653 5.27815E-05 8.958249 25 5.208 220.3764 5.27815E-05 8.958249 26 5.208 229.0998 5.27815E-05 8.958249 27 5.208 237.8232 5.27815E-05 8.958249 28 5.208 246.5466 5.27815E-05 8.958249 29 5.208 255.27 5.27815E-05 8.958249 30 5.208 263.9934 5.27815E-05 8.958249

212

Table A-16: Oxygen permeation studies on PET +0.65 LA SSE amorphous film

PET + 0.65 SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 4.3832 8.7664 4.43E-05 8.96796 2 4.3112 17.3888 4.31E-05 8.727514 3 4.2632 25.9152 4.25E-05 8.607387 4 4.2152 34.3456 4.27E-05 8.651486 5 4.1672 42.68 4.22E-05 8.554181 6 4.1672 51.0144 4.22E-05 8.554181 7 4.3112 59.6368 4.42E-05 8.960048 8 4.3352 68.3072 4.37E-05 8.865904 9 4.3352 76.9776 4.37E-05 8.865904 10 4.3352 85.648 4.37E-05 8.865904 11 4.3352 94.3184 4.37E-05 8.865904 12 4.5272 103.3728 4.54E-05 9.19196 13 4.2632 111.8992 4.31E-05 8.740001 14 4.3592 120.6176 4.37E-05 8.858399 15 4.3592 129.336 4.37E-05 8.858399 16 4.3592 138.0544 4.37E-05 8.858399 17 4.3592 146.7728 4.37E-05 8.858399 18 4.3592 155.4912 4.37E-05 8.858399 19 4.3592 164.2096 4.37E-05 8.858399 20 4.5752 173.36 4.53E-05 9.172432 21 4.1432 181.6464 4.12E-05 8.350382 22 4.1192 189.8848 4.12E-05 8.351681 23 3.9824 197.8496 4.04E-05 8.177568 24 4.1672 206.184 4.23E-05 8.564244 25 4.1672 214.5184 4.23E-05 8.564244 26 4.0232 222.5648 4.04E-05 8.187102 27 4.2632 231.0912 4.33E-05 8.782291 28 4.0472 239.1856 4.08E-05 8.270406 29 4.1 247.3856 4.16E-05 8.431097 30 4.3832 8.7664 4.43E-05 8.96796

213

Table A-17: Oxygen permeation studies on PET +0.9 LA SSE amorphous film

PET + 0.9 SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 4.3625 6.1075 4.38E-05 6.206383 2 5.725 14.1225 5.8E-05 8.229693 3 5.6 21.9625 5.67E-05 8.050005 4 5.6 29.8025 5.6E-05 7.945259 5 6.2 38.4825 6.2E-05 8.796537 6 5.6 46.3225 5.6E-05 7.945259 7 5.6 54.1625 5.6E-05 7.945259 8 5.6 62.0025 5.6E-05 7.945259 9 5.6 69.8425 5.6E-05 7.945259 10 3.65 74.9525 3.65E-05 5.178606 11 6.025 83.3875 6.03E-05 8.548247 12 6.05 91.8575 6.13E-05 8.701378 13 6.05 100.3275 6.13E-05 8.701378 14 6.05 108.7975 6.13E-05 8.701378 15 6.05 117.2675 6.13E-05 8.701378 16 6.05 125.7375 6.13E-05 8.701378 17 6.05 134.2075 6.13E-05 8.701378 18 6.05 142.6775 6.13E-05 8.701378 19 6.05 151.1475 6.13E-05 8.701378 20 6.05 159.6175 6.13E-05 8.701378 21 6.05 168.0875 6.13E-05 8.701378 22 6.05 176.5575 6.13E-05 8.701378 23 6.05 185.0275 6.13E-05 8.701378 24 6.05 193.4975 6.13E-05 8.701378 25 6.05 201.9675 6.13E-05 8.701378 26 6.05 210.4375 6.13E-05 8.701378 27 6.05 218.9075 6.13E-05 8.701378 28 6.05 227.3775 6.13E-05 8.701378 29 4.3625 6.1075 4.38E-05 6.206383 30 5.725 14.1225 5.8E-05 8.229693

214

Table A-18: Oxygen permeation studies on PET SSE oriented film

PET SSE Oriented

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 8.09 6.70 8.19E-05 6.87 2 8.13 13.44 8.21E-05 6.89 3 8.54 20.52 8.57E-05 7.19 4 8.58 27.63 8.63E-05 7.25 5 9.26 35.30 9.28E-05 7.79 6 8.67 42.49 8.72E-05 7.32 7 8.67 49.67 8.65E-05 7.27 8 9.39 57.46 9.46E-05 7.94 9 8.49 64.49 8.54E-05 7.17 10 8.58 71.61 8.67E-05 7.28 11 8.81 78.91 8.88E-05 7.46 12 9.30 86.61 9.26E-05 7.78 13 9.66 94.62 9.71E-05 8.15 14 9.21 102.26 9.30E-05 7.81 15 9.21 109.89 9.30E-05 7.81 16 9.21 117.52 9.30E-05 7.81 17 9.21 125.16 9.30E-05 7.81 18 9.21 132.79 9.30E-05 7.81 19 9.21 140.43 9.30E-05 7.81 20 9.21 148.06 9.30E-05 7.81 21 9.21 155.70 9.30E-05 7.81 22 9.21 163.33 9.30E-05 7.81 23 9.21 170.96 9.30E-05 7.81 24 8.54 178.04 8.62E-05 7.23 25 8.58 185.15 8.66E-05 7.27 26 9.26 192.82 9.34E-05 7.84 27 8.67 200.01 8.75E-05 7.35 28 8.67 207.20 8.75E-05 7.35 29 9.39 214.98 9.48E-05 7.96 30 8.49 222.02 8.57E-05 7.20

215

Table A-19: Oxygen permeation studies on PET+ 0.25 LA SSE oriented film

PET+0.25 SSE Oriented

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 9.09 5.91 9.14E-05 6.02 2 9.00 11.76 9.03E-05 5.94 3 9.39 17.86 9.47E-05 6.24 4 9.51 24.04 9.58E-05 6.31 5 9.54 30.24 9.60E-05 6.32 6 9.33 36.31 9.37E-05 6.17 7 9.15 42.26 9.21E-05 6.07 8 9.45 48.40 9.54E-05 6.28 9 9.15 54.35 9.17E-05 6.04 10 8.94 60.16 8.96E-05 5.90 11 9.12 66.09 9.21E-05 6.07 12 9.21 72.07 9.32E-05 6.14 13 9.21 78.06 9.32E-05 6.14 14 9.21 84.05 9.32E-05 6.14 15 9.21 90.03 9.32E-05 6.14 16 9.21 96.02 9.32E-05 6.14 17 9.21 102.00 9.32E-05 6.14 18 9.21 107.99 9.32E-05 6.14 19 9.00 113.84 9.03E-05 5.94 20 9.39 119.94 9.47E-05 6.24 21 9.51 126.13 9.58E-05 6.31 22 9.54 132.33 9.60E-05 6.32 23 9.33 138.39 9.37E-05 6.17 24 9.15 144.34 9.21E-05 6.07 25 9.45 150.48 9.54E-05 6.28 26 9.15 156.43 9.17E-05 6.04 27 8.94 162.24 8.96E-05 5.90 28 9.12 168.17 9.21E-05 6.07 29 9.21 174.15 9.32E-05 6.14 30 9.21 180.14 9.32E-05 6.14

216

Table A-20: Oxygen permeation studies on PET+0.5 LA SSE oriented film

PET+0.5 SSE Oriented

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 8.62 4.65 8.72E-05 4.77 2 9.87 9.98 9.97E-05 5.45 3 10.41 15.60 1.04E-04 5.71 4 9.72 20.85 9.75E-05 5.33 5 10.17 26.35 1.02E-04 5.57 6 9.78 31.63 9.83E-05 5.38 7 9.63 36.83 9.60E-05 5.25 8 9.81 42.12 9.88E-05 5.40 9 10.11 47.58 1.02E-04 5.56 10 10.35 53.17 1.04E-04 5.72 11 10.62 58.91 1.07E-04 5.86 12 10.47 64.56 1.04E-04 5.70 13 10.47 70.21 1.04E-04 5.70 14 10.47 75.87 1.04E-04 5.70 15 10.47 81.52 1.04E-04 5.70 16 10.47 87.18 1.04E-04 5.70 17 10.47 92.83 1.04E-04 5.70 18 10.47 98.48 1.04E-04 5.70 19 9.87 9.98 9.97E-05 5.45 20 10.41 15.60 1.04E-04 5.71 21 9.72 20.85 9.75E-05 5.33 22 10.17 26.35 1.02E-04 5.57 23 9.78 31.63 9.83E-05 5.38 24 9.63 36.83 9.60E-05 5.25 25 9.81 42.12 9.88E-05 5.40 26 10.11 47.58 1.02E-04 5.56 27 10.35 53.17 1.04E-04 5.72 28 10.62 58.91 1.07E-04 5.86 29 10.47 64.56 1.04E-04 5.70 30 10.47 70.21 1.04E-04 5.70

217

Table A-21: Oxygen permeation studies on PET+0.65 LA SSE oriented film

PET+0.65 SSE Oriented

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 7.68 5.46 7.84E-05 5.65 2 8.26 11.34 8.38E-05 6.03 3 7.01 16.32 7.07E-05 5.09 4 8.01 22.01 8.02E-05 5.78 5 7.06 27.03 7.08E-05 5.10 6 7.21 32.16 7.24E-05 5.21 7 7.01 37.14 7.09E-05 5.11 8 7.18 42.25 7.26E-05 5.23 9 7.11 47.31 7.25E-05 5.22 10 7.76 52.82 7.81E-05 5.63 11 7.71 58.31 7.69E-05 5.54 12 7.28 63.48 7.32E-05 5.28 13 8.51 69.53 8.59E-05 6.19 14 8.41 75.51 8.38E-05 6.04 15 5.96 79.75 6.00E-05 4.32 16 6.13 84.11 6.29E-05 4.54 17 6.13 88.47 6.29E-05 4.54 18 6.13 92.84 6.29E-05 4.54 19 6.13 97.20 6.29E-05 4.54 20 8.01 22.01 8.02E-05 5.78 21 7.06 27.03 7.08E-05 5.10 22 7.21 32.16 7.24E-05 5.21 23 7.01 37.14 7.09E-05 5.11 24 7.18 42.25 7.26E-05 5.23 25 7.11 47.31 7.25E-05 5.22 26 7.76 52.82 7.81E-05 5.63 27 7.71 58.31 7.69E-05 5.54 28 7.28 63.48 7.32E-05 5.28 29 7.76 52.82 7.81E-05 5.63 30 7.71 58.31 7.69E-05 5.54

218

Table A-22: Oxygen permeation studies on PET+0.9 LA SSE oriented film

PET+0.9 SSE Oriented

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 6.78 4.20 6.83E-05 4.29 2 6.66 8.33 6.69E-05 4.20 3 6.90 12.61 6.98E-05 4.38 4 6.96 16.93 6.94E-05 4.36 5 6.72 21.09 6.75E-05 4.24 6 6.81 25.31 6.98E-05 4.39 7 6.81 29.54 6.98E-05 4.39 8 6.81 33.76 6.98E-05 4.39 9 6.81 37.98 6.98E-05 4.39 10 6.81 42.20 6.98E-05 4.39 11 6.81 46.43 6.98E-05 4.39 12 6.81 50.65 6.98E-05 4.39 13 6.81 54.87 6.98E-05 4.39 14 6.54 58.92 6.64E-05 4.17 15 6.39 62.89 6.40E-05 4.02 16 6.51 66.92 6.54E-05 4.11 17 6.21 70.77 6.30E-05 3.96 18 6.66 74.90 6.64E-05 4.17 19 6.66 79.03 6.64E-05 4.17 20 6.66 83.16 6.64E-05 4.17 21 6.66 87.29 6.65E-05 4.18 22 6.72 91.46 6.69E-05 4.20 23 6.72 95.62 6.71E-05 4.21 24 6.78 4.20 6.83E-05 4.29 25 6.66 8.33 6.69E-05 4.20 26 6.90 12.61 6.98E-05 4.38 27 6.96 16.93 6.94E-05 4.36 28 6.72 21.09 6.75E-05 4.24 29 6.81 25.31 6.98E-05 4.39 30 6.81 29.54 6.98E-05 4.39

219

Table A-23: Oxygen permeation studies on PET RE control amorphous film

PET SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

220

Table A-24: Oxygen permeation studies on PET+0.11 RE amorphous film

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 0 0 0 0 2 2.3445 7.9713 2.33516E-05 8.04493 3 2.3625 16.0038 2.3518E-05 8.102257 4 2.5425 24.6483 2.52957E-05 8.714714 5 2.5125 33.1908 2.50259E-05 8.62175 6 2.7825 42.6513 2.77575E-05 9.56284 7 2.7225 51.9078 2.72326E-05 9.381997 8 2.4825 60.3483 2.50722E-05 8.637706 9 2.6025 69.1968 2.62985E-05 9.06018 10 2.6025 78.0453 2.61224E-05 8.999522 11 2.6925 87.1998 2.71252E-05 9.344982 12 2.7225 96.4563 2.75702E-05 9.498288 13 2.7225 105.7128 2.75702E-05 9.498288 14 2.7225 114.9693 2.75702E-05 9.498288 15 2.7225 124.2258 2.75702E-05 9.498288 16 2.7225 133.4823 2.75702E-05 9.498288 17 2.7225 142.7388 2.75702E-05 9.498288 18 2.7225 151.9953 2.75702E-05 9.498288 19 2.7225 161.2518 2.75702E-05 9.498288 20 2.7225 170.5083 2.75702E-05 9.498288 21 2.7225 179.7648 2.75702E-05 9.498288

221

Table A-25: Oxygen permeation studies on PET+0.33 RE amorphous film

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 2.86 6.4064 2.88519E-05 6.548607 2 3.2 13.5744 3.26641E-05 7.413871 3 2.86 19.9808 2.88889E-05 6.557008 4 2.92 26.5216 2.93435E-05 6.66019 5 2.66 32.48 2.67125E-05 6.063016 6 2.72 38.5728 2.73155E-05 6.199901 7 3.16 45.6512 3.19867E-05 7.260133 8 2.88 52.1024 2.91203E-05 6.609537 9 2.98 58.7776 3.01314E-05 6.839035 10 3.4 66.3936 3.43782E-05 7.802926 11 3.04 73.2032 3.07381E-05 6.976734 12 3.14 80.2368 3.17492E-05 7.206232 13 2.84 86.5984 2.87159E-05 6.517738 14 2.84 92.96 2.87159E-05 6.517738 15 3.22 100.1728 3.25581E-05 7.38983 16 2.88 106.624 2.91203E-05 6.609537 17 2.88 113.0752 2.91203E-05 6.609537 18 2.88 119.5264 2.91203E-05 6.609537 19 2.88 125.9776 2.91203E-05 6.609537 20 2.88 132.4288 2.91203E-05 6.609537

222

Table A-26: Oxygen permeation studies on PET RE control oriented film

PET SSE amorphous

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 2.76 7.057714 2.78456E-05 7.215034 2 2.31 12.96471 2.32769E-05 6.031246 3 2.43 19.17857 2.44587E-05 6.337469 4 2.34 25.16229 2.35256E-05 6.095692 5 2.25 30.91586 2.26367E-05 5.865371 6 2.37 36.97629 2.39377E-05 6.202464 7 2.25 42.72986 2.2555E-05 5.844204 8 2.13 48.17657 2.13849E-05 5.541011 9 2.19 53.77671 2.21185E-05 5.731102 10 2.22 59.45357 2.22334E-05 5.760852 11 2.19 65.05371 2.21862E-05 5.748636 12 2.28 70.884 2.30996E-05 5.985306 13 2.25 76.63757 2.26331E-05 5.864427 14 2.25 82.39114 2.26331E-05 5.864427 15 2.25 88.14471 2.26331E-05 5.864427 16 2.4 94.28186 2.42152E-05 6.27438 17 2.52 100.7259 2.54353E-05 6.590499 18 2.52 100.7259 2.54353E-05 6.590499 19 2.16 118.2167 2.1867E-05 5.665927 20 2.13 123.6634 2.15078E-05 5.572847 21 2.31 129.5704 2.32075E-05 6.01325 22 2.25 135.324 2.25666E-05 5.847193 23 2.34 141.3077 2.34956E-05 6.087919 24 2.34 147.2914 2.33937E-05 6.061505 25 2.37 153.3519 2.37147E-05 6.144684 26 2.43 159.5657 2.43851E-05 6.31839 27 2.55 166.0864 2.57202E-05 6.664316 28 2.55 172.6071 2.57217E-05 6.664719 29 2.64 179.358 2.66038E-05 6.89327 30 2.76 7.057714 2.78456E-05 7.215034

223

Table A-27: Oxygen permeation studies on PET+0.11 RE oriented film

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 1.84 16.14 1.85968E-05 6.406826 2 1.38 17.52 1.3878E-05 4.781151 3 1.38 18.9 1.38977E-05 4.78794 4 1.44 20.34 1.45532E-05 5.013784 5 1.46 21.8 1.47487E-05 5.081109 6 1.38 23.18 1.39269E-05 4.797991 7 1.44 24.62 1.45112E-05 4.999283 8 1.6 26.22 1.60831E-05 5.540856 9 1.38 27.6 1.38617E-05 4.775532 10 1.38 28.98 1.38617E-05 4.775532 11 1.38 30.36 1.38617E-05 4.775532 12 1.38 31.74 1.39724E-05 4.813682 13 1.1 32.84 1.1109E-05 3.827189 14 1.24 34.08 1.24742E-05 4.297533 15 1.3 35.38 1.30529E-05 4.496883 16 1.72 37.1 1.73082E-05 5.962894 17 1.44 24.62 1.45112E-05 4.999283 18 1.6 26.22 1.60831E-05 5.540856 19 1.38 27.6 1.38617E-05 4.775532 20 1.38 28.98 1.38617E-05 4.775532 21 1.38 30.36 1.38617E-05 4.775532

224

Table A-28: Oxygen permeation studies on PET+0.33 RE oriented film

Day OTR Qt Permeance Permiability CC/100in2 CC.mil/100in2 cc/(day.100in2) cc.mil/(100 in2.day.atm)

1 1.19 3.543555556 1.2E-05 4.136688 2 0.69 5.598222222 6.98E-06 2.404723 3 1.09 8.844 1.1E-05 3.79255 4 1.03 11.91111111 1.04E-05 3.565958 5 1.09 15.15688889 1.09E-05 3.766493 6 1.07 18.34311111 1.07E-05 3.702768 7 1.01 21.35066667 1.01E-05 3.477948 8 1.07 24.53688889 1.07E-05 3.683896 9 1.07 27.72311111 1.08E-05 3.703921 10 1.03 30.79022222 1.04E-05 3.578545 11 1.13 34.15511111 1.14E-05 3.925066 12 1.17 37.63911111 1.18E-05 4.06114 13 1.05 40.76577778 1.06E-05 3.653337 14 0.97 43.65422222 9.76E-06 3.362253 15 0.99 46.60222222 9.98E-06 3.437032 16 1.03 49.66933333 1.04E-05 3.587481 17 1.03 52.73644444 1.04E-05 3.584256 18 0.95 55.56533333 9.59E-06 3.304265 19 1.05 58.692 1.06E-05 3.645201 20 1.17 62.176 1.18E-05 4.051955

225