EFFECTS of BIO-FINISHING on COTTON and COTTON/WOOL BLENDED FABRICS by SHRIDHAR CHIKODI, B.Tech. a THESIS in CLOTHING, TEXTILES

Home , Finishing (textiles)

EFFECTS OF BIO-FINISHING ON COTTON AND COTTON/WOOL BLENDED FABRICS by SHRIDHAR CHIKODI, B.Tech. A THESIS IN CLOTHING, TEXTILES, AND MERCHANDISING Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE

Approved

Accepted

May, 1994 fjC fl£1-1 ;q;:; u goS TJ Jh ~t/'li I qq.lf /V/). I U>p·~

In accomplishing this work, there are many people who have inspired my determination. To begin with, I would like to thank my thesis committee chairman, Dr. Samina Khan, for her invaluable guidance and encouragement throughout this project.

I am thankful to Dr. Shelley Harp for the consistent support and attention to detail which was invaluable. I extend my sincere thanks to Dr. R.D. Mehta whose research expertise has been crucial to the success of this project.

I am also grateful to Dr. Jerry Mason, for his support throughout my stay at Tech.

I am indebted to the personnel at International Center for Textile Research and Development and to Mark Grimson at

Scanning Electron Microscopy lab, for their contribution to this research.

I would like to express my heartfelt thanks to my parents, for their undying love, faith and immeasurable sacrifices they have made on my behalf. I truly owe them everything.

A final acknowledgement I extend to my close friend

Janie, for her never-ending encouragement, support, and assistance in the past two years.

11 TABLE OF CONTENTS

.. ACKNOWLEDGMENTS . . . ll

LIST OF TABLES . vi

LIST OF FIGURES . viii CHAPTERS

I . INTRODUCTION 1

Statement of Problem . . 2

Purpose of the Study . 3

Assumptions 4

Hypotheses . . . . 5

Limitations 5

Definition of Terms 6

II. REVIEW OF RELATED LITERATURE . 10

Structural Properties of Cotton Fibers . . . 12

Structural Properties of Wool Fibers . . . 16

A Review of Cellulase and Protease Enzymes . . 21

Cellulase Enzymes . . 21

Protease Enzymes . . 23

Summary . . 23

III. METHODOLOGY 25

Description of the Experimental Fabrics . 25

Fabric Development Procedure ...... 25

Warp and Filling Yarn Production . 27

Fabric Construction . . . 2 7

Enzyme Treatment on Experimental Fabrics . . • 2 8

Application of Cellulase Enzymes ...... 28

iii Application of Protease Enzymes . • 2 9

Physical Tests . . . 2 9

Test for Breaking Strength . . . 31

Test for Abrasion Resistance . . 3 3

Test for Dimensional Stability to Laundering . 33

Test for Fabric Stiffness . . . . . 33

Test for Wrinkle Recovery . . . . 34

Test for Pilling Resistance . . . 34

Fabric Hand ...... 34

Scanning Electron Microscope . 35

Analysis of Data . • • • 3 6

IV. ANALYSIS OF DATA . . 37

Description of Sample . . . 3 7

Analysis of Hypotheses . • • 3 8

Hypothesis 1.a • • • 3 9

Hypothesis 1.b . . 43

Hypothesis 1.c . . 52

Hypothesis 1.d . 60

Hypothesis 1.e . . 64

Hypothesis 2 . 70

Scanning Electron Micrograph Results of Surface Appearance ...... 77

Hypothesis 3 . 82

Summary of Data Analyses ...... 85

V. SUMMARY, FINDINGS, CONCLUSIONS AND RECOMMENDATIONS . 89

Summary of the Study . . 90

Discussion of Findings and Conclusions . 91

iv Hypothesis l.a . . . . . 91

Hypothesis l.b . 92

Hypothesis l.c . • 92

Hypothesis l.d ...... 93

Hypothesis l.e . . 93

Hypothesis 2 . . . 94

Hypothesis 3 . 94

Recommendations for Further Research . • 93

REFERENCES ...... 96

APPENDIX: WEIGHT LOSS TEST RESULTS . • 9 9

v LIST OF TABLES

3.1 Physical Properties of the Experimental Fibers and Fabrics ...... 26

3.2 Description of Physical Tests . 30

3.3 Rating Scale Score Sheet . . . . • • 3 2

4.1 Means and Standard Deviations of Breaking Strength (lbs) in Warp and Filling Directions . . 4 0

4.2 Percentage Strength Loss After Enzyme Treatments .. 41

4.3 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Breaking Strength in Warp Direction ...... 44

4.4 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Breaking Strength in Filling Direction ...... 45

4.5 Means and Standard Deviations of Abrasion Resistance (cycles) in Warp and Filling Directions . 47

4.6 Percentage Loss in Abrasion Resistance After Enzyme Treatments ...... 48

4.7 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Abrasion Resistance in Warp Direction ...... 50

4.8 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Abrasion Resistance in Filling Direction . . . . . 51

4.9 Means and Standard Deviations of Dimensional Stability (inches) in Warp Direction ...... 53

4.10 Percentage Shrinkage in Warp Direction After Enzyme Treatments ...... 54

4.11 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Dimensional Stability in Warp Direction with 3% Treatment . 58

4.12 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Dimensional Stability in Warp Direction with 5% Treatment . 59 . Vl 4.13 Means and Standard Deviations of Fabric Stiffness in Warp and Filling Directions ...... 61

4.14 Overall Flexural Rigidity After Enzyme Treatments . 62

4.15 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Fabric Stiffness in Warp Direction ...... 65

4.16 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Fabric Stiffness in Filling Direction ...... 66

4.17 Means and Standard Deviations of Wrinkle Recovery (degrees) in Warp and Filling Directions ...... 67

4.18 Wrinkle Recovery in Degrees in Warp and Filling Directions After Enzyme Treatments . . . . . 68

4.19 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Wrinkle Recovery in Warp Direction ...... 71

4.20 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Wrinkle Recovery in Filling Direction ...... 72

4.21 Means and Standard Deviations of Pilling Resistance 74

4.22 Interjudge Reliability of Pilling Ratings (Pearson Correlation Coefficients) ...... 76

4.23 One-Way ANOVA and Tukey's Studentized Range Test Results--Influence of Fiber Content on Pilling Resistance ...... 81

4.24 Mean and Standard Deviations of Fabric Hand .. 83

4.25 Interjudge Reliability of Fabric Hand Evaluation (Pearson Correlation Coefficients) ...... 84

4.26 One-Way ANOVA and Tukey's Studentized Range Test Results--Subjective Evaluation of Fabric Hand . 86

A.1 Percentage Weight Loss After Enzyme Treatments . 101

.. Vl.l. LIST OF FIGURES

2.1 Chemical Structure of Cellulose . . 15

2.2 Chemical Reaction of Enzyme on Cellulose . . . . 17

2.3 Chemical Structure of Wool . . • • . 2 0

3.1 Rating scale Score Sheet . . 32

4.1 Percentage Strength Loss . . . 42

4.2 Percentage Loss in Abrasion Resistance . . . 4 9

4.3 Percentage Shrinkage After One Wash ...... 55

4.4 Percentage Shrinkage After Five Washes . . • 56

4.5 Fabric Stiffness . 63

4.6 Wrinkle Recovery in Degrees . 69 4.7 Pilling Resistance ...... 75

4.8 SEM's of 100% Cotton Fabrics ...... 78

4.9 SEM's of 90/10 Cotton/Wool Fabrics . . . . . 79

4.10 SEM's of 70/30 Cotton/Wool Fabrics ...... 80 A.1 Percentage Weight Loss After Enzyme Treatments 102

viii CHAPTER I

INTRODUCTION

Enzymes or bio-catalysts have been utilized on a large scale for more than 75 years in medical investigation-to supplement the body digestive system, in food processing to enrich grains and cereals, in wine production to ferment grapes and in the domestic detergency area to improve overall cleaning performance by leaving fabrics smoother, with decreased ability to trap dirt. Since the beginning of the 20th century, enzymes have been used in textile desizing. However, the concept of treating fabrics produced from low-grade fibers with enzymes (also known as hie polishing or bio-finishing) to improve surface properties was first developed in Japan in 1989.

The main objective of bio-finishing is to create a fabric from low-grade fibers with smooth appearance and improved softness without the use of conventional chemicals which result in toxic effluent (Garrett & Cedroni, 1990).

Recent technical applications of enzymes have revealed that it is possible to remove substances such as pectin, hemicellulose, lignin, seed husks, vegetable matters, skin grease, suint and skin residue that accompany natural fibers

(Hemmpel, 1991).

Cotton and wool fibers are made up of fibers, some of which protrude. These loose fibers which tend to protrude

1 2 from yarn surface are responsible for the formation of

"fuzz." Conventionally, the protruding fibers are removed either by burning off by flame or by infrared radiation or by passing over hot copper plates. These conventional treatments bring about a temporary change to the fabric surface. However, treatment with cellulase and protease enzymes degrades the protruding fibers permanently, giving a smoother fiber surface, which result in a simultaneous improvement of hand and luster (Schubel, 1990; Hemmpel, 1991) .

Cellulase and protease enzyme treatments avoid the high alkaline pollution caused by chemicals during cotton and wool scouring processes, which otherwise would pose a high environmental risk (Hemmpel, 1990). Consequently, it is possible to permanently finish a low-grade inexpensive fabric to look and feel like a top quality fabric in a more environmentally friendly way. At this point in time, no research has been undertaken in the United States, with respect to treating cotton/wool blended fabrics with enzymes. Therefore, the void in this area of textile development serves as a basis for the present study.

Statement of Problem

Modification of textile materials in an environmentally safe way is of paramount certain in an increasingly technological based textile industry. Bio-finishing is one 3 such technological advancement where by means of enzymatic treatment, scouring a major textile finishing process is avoided, thus eliminating the high alkaline pollution.

Research on hie-finishing 100% cotton fabrics has been reported; however, no published research exists concerning the effects of enzyme treatment on cotton/wool blended fabrics. It is expected that the study undertaken here will make a genuine contribution to the existing body of knowledge in textile finishing.

Purpose of the Study

The purpose of this study was threefold: (1) to obtain and treat cotton and cotton/wool blended fabrics with cellulase and protease enzymes; (2) to examine the surface appearance of treated and untreated cotton and cotton/wool blended fabrics, and (3) to assess the differences in selected physical properties between treated and untreated cotton and cotton/wool blended fabrics. In order to accomplish these purposes the following steps were necessary: (a) to secure fabrics manufactured at the

International Center for Textile Research and Development

(ICTRD) of selected cotton-wool fiber content;

(b) to apply cellulase enzymes to the 100% cotton fabric and cellulase and protease enzymes to the 90/10 and

70/30 cotton/wool blended fabrics; 4

(c) to study the effect of enzyme finishing on the surface characteristics of treated and untreated cotton and cotton/wool blended fabrics using a scanning electron microscope;

(d) to compare the selected physical properties of treated and untreated cotton and cotton/wool blended fabrics;

(e) to assess the fabric hand of treated and untreated cotton and cotton/wool blended fabrics using a subjective evaluation technique.

Assumptions

The following assumptions were made for the study:

1. Consumer demand for quality fabrics made from 100% cotton and cotton/wool blends will continue to increase.

2. Refining of surface properties to produce smoother and higher quality fabrics will contribute to the expansion of the 100% cotton and cotton/wool blended fabric market.

3. Primary producers of low-grade cotton and wool fiber would benefit economically from commercial application of bio- finishing.

4. Textile manufacturers will continue to search for environmentally safe methods for textile production.

5. Consumer concern with environmental issues will continue to impact product development and marketing strategy. 5 Hypotheses

Based on the purposes and assumptions of the study, the following null hypotheses were formulated:

1. There are no significant differences in the physical test results for treated and untreated cotton and cotton/wool blended fabrics with regard to:

(a) breaking strength in warp and filling directions.

(b) abrasion resistance in warp and filling directions.

(d) fabric stiffness in warp and filling directions.

(e) wrinkle recovery in warp and filling directions.

2. There are no significant differences in the surface appearance of the treated and untreated cotton and cotton/wool blended fabrics with regard to pill formation.

3. There are no significant differences in subjective evaluation of the treated and untreated cotton and cotton/wool blended fabrics with regard to fabric hand.

Limitations

The following limitations were recognized in this research: 1. Experimental fabrics were developed from West Texas

Pima cotton and Texas wool fibers.

2. Experimental fabrics were limited to plain weave. 6

3. Experimental fabrics were limited to two cotton/wool blend levels.

4. Two concentrations of cellulase and protease enzymes were applied to the experimental fabrics.

5. Enzyme application conditions (pH, temperature and time) remained constant throughout the study.

6. Selected physical tests were utilized on the experimental fabrics.

Definition of Terms

The following terms were defined for the purposes of the study:

Abrasion resistance--The degree to which a fabric is able to withstand rubbing, surface wear and other frictional forces.

American Association of Textile Chemists and Colorists

(AATCC)--A professional association made up of individual members/responsible for the yearly publication of the AATCC technical manual containing the most current versions of all standard AATCC test methods and some related information.

American Society for Testing and Materials(ASTM)--A non-profit corporation formed in 1898 for the development of standards on characteristics and performance of materials, products, systems, and services, and the promotion of related knowledge. 7

Amorphous Region--The random molecular chains in fibers.

Biochemical Oxygen Demand (BOD)--The amount of dissolved oxygen required to meet the metabolic need of microorganisms in organic matter.

Bio-finishing--A finishing treatment given to the fabrics in which enzymes are used under controlled pH and temperature for a specific duration of time to get a smoother appearance and improved softness.

Breaking strength--The maximum tensile force recorded in extending a test piece to breaking point.

Carding--A process by which staple fibers are separated and aligned into a sliver during yarn spinning.

Catalyst--A relatively small amount of a substance which facilitates a chemical reaction but takes no part in it.

Cellulase--An enzyme that hydrolyses cellulose.

Crystalline Region--The orderly packed molecular chains in fiber. Dimensional change--The changes in length or width of the fabric when subjected to specified conditions.

Drawing--An operation by which card slivers are blended, doubled, or levelled, and reduced to the state of sliver or roving suitable for spinning. 8

Enzyme--Any group of complex proteins produced by living cells and acting as catalysts in biochemical reactions.

Experimental fabrics--A collective term for fabric samples used in the study.

Fibril--The microfibrils which combine into larger crystalline groups.

Flexural rigidity--A measure of the resistance of materials to bending by external forces. It is related to stiffness and is one of the factors sensed when a fabric is handled.

Hydrolysis--The chemical decomposition of a substance by the action of water. The result of hydrolysis upon fiber polymers will result in the rupture of inter-polymer forces of attraction.

International Center for Textile Research and

Development (ICTRD)--A research facility of Texas Tech

University, Lubbock, Texas, which has the capacity of converting fibers to a finished fabric.

Microfibril--The individual crystalline areas in a fiber.

Filling--The formation of little balls of fuzz (pills) on the surface of the fabric.

Pima cotton--A variety of long staple cotton fiber.

Polar Group--A group of atoms which are charged either negatively or positively. 9

Protease--An enzyme that hydrolyses proteins, especially peptides.

Resiliency--The ability of fiber or fabric to spr1ng back, recoil, or return to its original form or shape after

compression.

Roving--A relatively fine fibrous strand used in the

later or final processes of preparation for spinning.

Singeing--Is the removal of protruding fibers from the

surface of yarn or fabric by burning.

Slashing--A process of applying stiffening materials to

warp yarn to withstand the weaving operation.

Stiffness--A property concerned with the feel of the

fabric. CHAPTER II REVIEW OF RELATED LITERATURE

Low grade fibers are characterized by staple length and foreign material. The shorter the staple length and higher the percentage of foreign material present, the lower will be the fiber grade. Staple length is biological in origin.

Variation in staple length can be traced down to a single seed of cotton or lock of wool (Morton & Hearle, 1975).

Therefore, the variety of seed, type of breed, and climatic conditions of the region create varying properties in staple length. Foreign material present with fibers depends upon farming and ranching as well as harvesting and shearing techniques.

Staple length has a pronounced influence on the quality of the fabric produced. Longer fibers are finer and smaller in diameter than short fibers, and stay in the core during yarn formation, where as short fibers are often found protruding on the yarn exterior (Klein, 1986) . These short fibers are mainly responsible for the formation of the pill.

Usually these protruding short fibers are removed by burning off. This removal is temporary, and the short fibers come back to the surface after a few washes. However, by enzymatic degradation, these short fibers can be permanently removed, hence replacing the conventional singeing process to a certain extent (Schubel, 1990).

10 11

During the past few years, concern with environmental

issues associated with matters such as occupational health

and consumer product safety has grown at an ever increasing

pace. Currently consumers are concerned with the

environmental friendliness of the products they buy. Today

the environment acts as a major influence on product

development and marketing strategy (Coddington, 1993). As

stated by Ottman (1993), all else being equal, the product

that is environmentally safe will have an unbeatable edge in

tomorrow's marketplace.

Considering the total environment, the role that the

textile industry plays therein is very significant. Among

the textile industry's more serious environmental

preservation problems are air pollution inside the textile

mill and disposal of solid waste. Textile processing has

always resulted in water pollution as large volumes of water

used in finishing processes tend to produce extremely

polluting effluent.

The cotton scouring process is designed to remove

natural impurities (waxes, pectins and alcohols) present on

the fiber to improve dyeability. This scouring process produces about 20-40 pounds of BOD for every thousand pounds of cotton scoured. The wool scouring process removes wool wax, suint and other matters of vegetable origin. This process produces a very high load of approximately 250 pounds of BOD for every thousand pounds of wool produced 12

(Massellie, Massellie & Burford, 1977} . Cotton and wool scouring processes can be avoided, by means of enzymatic treatment, thus eliminating the high alkaline pollution.

The development of a bio-finished fabric requ1res a complete study of various parameters that make up the specific fabric. Among the primary considerations are the morphology, surface properties and chemical structure of fibers and enzyme applications. The review of related literature is divided into three sections as follows: (a} structural properties of cotton fibers, (b) structural properties of wool fibers, and (c) a review of cellulase and protease enzymes.

Structural Properties of Cotton Fibers

Cotton, one of the three major natural fibers is nearly pure cellulose. The basic unit of the cellulose molecule is the glucose unit, which consists of the chemical elements carbon, hydrogen and oxygen. The repeating unit of cellulose molecule is called cellobiose, which is made up of two glucose units. The cotton polymer has about 5000 cellobiose units, hence its degree of polymerization is about 5000 (Gohl & Vilensky, 1987}. The cellulose molecules are held together by hydrogen bonds to form microfibril.

These microfibril align themselves to form crystalline regions called fibrils (Meredith, 1975} . A group of fibrils form the cellulose fibers. 13

Approximately 70% of the cotton fiber is made up of crystalline region and the remaining is amorphous region.

(Gohl & Vilensky, 1987). In the crystalline region the molecules are packed in orderly form, making the fiber strong and relatively inelastic. However, in the amorphous region, the molecules are found in unorderly form causing voids and irregularity in structure, hence making the fiber hygroscopic in nature, allowing the penetration of dyestuff and chemicals (Morton & Hearle, 1975; Needles, 1987).

The cross section of cotton fiber consists of a number of concentric layers. These layers consists of three basic areas. The primary wall or cuticle forms the outer most region; the bulk of the fiber is made up of the secondary wall and the center is a narrow lumen (Balls, 1928).

The primary wall forms a protective layer, which contains non-cellulosic materials like waxes, fats and pectin as well as cellulose fibrils. Cellulose fibrils forming the primary wall give greater peripheral strength and are responsible for resisting forces from any lateral direction (Balls, 1928). The secondary wall is built up of closely lying cellulose fibrils, amounting to 90% of the total fiber weight. These fibrils lie in spiral formation along the fiber axis, reversing in direction periodically, and exerting maximum strength in the longitudinal direction

(Balls, 1928). The reversal in direction of the spiral 14 formation is responsible for a small degree of elasticity and twisted shape of the fiber (Raes, Fransen & Verschrage, 1974) .

The lumen is the hollow space at the center of the fiber which is often partly filled with a remanent of protoplasm, when the fiber is dried. It is highly irregular in both size and shape and provides nutrients to the developing fiber (Hamby, 1949).

The chemical structure of cellulose is very important with respect to the finishing properties of the fiber.

According to the best available evidence, cellulose consists of long chains of the condensation products of ~-glucose.

The chemical structure of cellulose is shown in Figure 2.1.

The chemically reactive groups in cellulose are called hydroxyl or OH groups. They are polar and therefore attract water molecules. Thus the hydroxyl groups are mainly responsible for high moisture absorption. Hydrogen atoms along with oxygen atoms form hydrogen bonds. These bonds draw molecules close to each other and increase the strength of the fiber (Morton & Hearle, 1975).

The oxygen bridges between ~-glucose residues known as

1,4 glucosidic linkages are formed by elimination of water between carbon atom 1 and carbon atom 4. Cellulase enzymes which are capable of degrading cellulose, perform a specific catalytic action on the 1,4-~-glucosidic linkages of the cellulose molecules. The hydrolysis of this linkage 15

primary alcohol group

cellobiose unit glucose umt

Figure 2.1. Chemical Structure of Cellulose 16 separates the cellulose molecules into smaller particles which may be further reduced (Hemmpel, 1991). The chemical reaction is shown in Figure 2.2.

Structural Properties of Wool Fibers

Wool, a natural protein fiber, grows from an opening in the sheep's skin called follicle. The wool molecule consists of flexible molecular chains held together by natural cross-links, sulphur links, and salt bridges that connect the adjacent molecules. Keratin, a protein substance, the principal constituent of wool fiber is composed of 18 amino acid residues (Joseph, 1986) . The proportions of amino acids and their sequence vary with the variety of wool. The amino acids which form repeating polyamide units are responsible for the overall properties of the resultant fiber (Lyle, 1982) .

Wool fiber in its normal relaxed state has a helical configuration called an alpha-keratin and in its stretched state has a beta-keratin configuration. When the tension used to form the beta-keratin is removed the wool polymer tends to return to alpha-keratin configuration mainly due to inter-polymer disulfide bonds. This phenomenon is responsible for the high elastic recovery and resiliency of the wool fiber (Meredith, 1975; Gohl & Vilensky, 1987). The alpha and beta keratin are present in the crystalline 17

CH 0H H OH 2 I I HH I "-hH /"A 0 /0

/c"~ "'- /Vt 6>~I I 0 OH C~OH *

+EnzymeI I

H ~OH I I "-hi! A 0 /0 c"'fI I /c"~ OH 6>~I J OH ~ OH C~OH

Figure 2.2. Chemical Reaction of Enzyme on Cellulose 18 regions of the fiber and account for 40% of the whole

(Morton & Hearle, 1975).

There are three distinct structural parts in the wool fiber. The cuticle or epidermis layer forms the outer most region, the bulk of the fiber is made up of cortex and the center is a hollow core or medulla (Cook, 1968) .

The cuticle, outermost layer of wool, is a scaley non fibrous membrane. The scales overlap and point towards the tip of the fiber causing a directional effect. This phenomenon is important in the frictional properties of the fiber (Morton & Hearle, 1975) . The cuticle is covered with a waxy film known as epicuticle and is the only non-protein membrane of the fiber. This layer gives the water repellency to the fiber (Cook, 1968) .

The major portion of the fiber, cortex or core, is enclosed within the cuticle, and amounts to about 90% of the fiber volume (Joseph, 1986). It is made up of long flattened cells. "The cross linked amino acids form fibrils, which in turn make up the spindle-shaped cortical cells which constitute the cortex of the fiber" (Needle, 1986, p 61).

The cortical cells are not alike and are made up of two distinct sections. These are known as ortho-cortex and the para-cortex cells, and they spiral around one another along the fiber length. These two parts respond differently to the changes in environment and this accounts for wool's natural waviness (Morton & Hearle, 1975) . 19

The center most region, medulla, is prominent in immature fibers and is nearly invisible in matured fibers.

It allows the nutrients to reach the fiber during the growth phase. It has a honey-comblike core containing air spaces that make the fiber lighter and increase its insulating power (Smith & Block, 1982) .

The chemical structure of wool is very important in determining the properties of the fibers. Amino acids linked to each other by peptide bonds form the repeating unit of wool polymer. The peptide chains are adjoined at intervals by cystine (-8-8-) and salt (NH2± -) linkages.

These linkages contribute to the excellent elastic recovery and resiliency of the fiber. The absorbency of the wool fiber is due to the polarity of peptide groups and salt linkages, which attract water molecules (Gohl & Vilensky,

1987) . The chemical structure of wool is shown in Figure

2 . 3 . Protease enzymes, which are capable of degrading wool fiber, perform a specific action on the peptide bonds and cystine linkages. Enzymes act on the interior of peptide bonds and cystine linkages and break them (Lyle,1982;

Gerhartz, 1990). The role of protease enzymes with regard to hie-finishing has not been reported in depth. 20

"C=O C/ -C-H/ H-C" "N-H H-N/ O=C/ "C=O H-"C- CH2- S-S- CH2- C-/ H H/ _ N Cystme . 1·an k age '\.,_N _ H '\.,_ (disulfide) / C=O O=C -C-H/ H-C" ~N-H" H-N~/

C=O C=O -C-H/ H-C" "N-H H-N / o=c/ "c-o H /'t-CHz-CHz-COO- •NH 3 -CH 2 -CH,-CH~-CH,-C/H-- . - H"'- N Giutamac ac1o Lysone ) _ H

C=O 1 O=C / lonac bonds "- H- C (salt linkages) H- C "'N-H I H-N / O=C/ \=o

H-"'C- CH2 - COO- •NHJ- C - NH - CH2 - CH 2 - CH 2 - C-/ H H _ N/ AspartiC acad ~~ Arganane \ _ H " /

Figure 2.3. Chemical Structure of Wool 21

A Review of Cellulase and Protease Enzymes

"An enzyme is an organic molecule of biological origin, proteinaceous in nature, of comparatively high molecular weight, and very importantly, is a catalyst capable of significantly accelerating the rate of particular chemical reaction" (Wolnak, 1978, p.3). The activities of enzymes have been recognized for thousands of years; however, only recently have their properties have been understood thoroughly (Gerhartz, 1990).

Enzymes are produced by cultivation of microorganisms in a stable medium. The common commercial enzymes that are found in today's market are: alpha-Amylase, beta-Glucanase,

Cellulase, Dextranase, Glucoamylase, Hemicellulase, Lactase,

Lipase, Mutanase, Pectinase, Protease, and Pullulanase

(Aunstrup, 1979) . Since the textile industry uses cellulase frequently and the use of protease is under consideration, these two enzymes are reviewed in the following sections.

Cellulase Enzymes The cellulase enzymes are commonly obtained by fermentation using the microorganism Trichoderma reesei.

These natural protein products show good activity against native cellulose and accelerate bio-degradation of cotton cellulose. Cellulases are active at pH 4 to 6 (acidic conditions) exhibit maximum activity at a temperature of 40- 22 ssoc, and can be deactivated at temperatures above 65°C (Aunstrup, 1979) .

Cellulase enzymes perform a specific catalytic action on the

1,4 beta-glucosidic bonds of the cellulose molecules. The hydrolysis of this bond leads to the formation of the molecules into smaller units which may be further degraded.

A controlled hydrolysis of cellulosic fibers brings about a smooth, pill free surface (Schubel, 1990).

Cellulase is a large molecule enzyme, making it difficult to enter the interior crystalline region of the cellulose fiber. Thus initially, it acts on the surface and breaks the cellulose chains randomly. Then it specifically attacks the open structure in particular. During this action loose fibers break off (Schubel, 1990; Hemmpel,

1991) .

In recent years, cellulase enzymes have been used to degrade fiber surfaces, dyestuffs and surface fibers

(Schubel, 1990). Denim jeans are treated with cellulase enzymes to get stone washed and diamond washed effects.

Cellulase enzymes are particularly suitable for this purpose, as denim jeans are dyed with indigo dyes which stay on the surface of the fabric. Removing surface dye by using stones abrades the fabric surface, whereas cellulase enzymes remove surface dye by partially hydrolyzing the surface of the fibers in a short time. In this way, denim jeans get a stone washed effect in a short time with high consistency. 23 This process not only improves the quality of the working

environment but also prevents damage to washing machines

(Kochavi, Videbaek & Cedroni, 1990).

Protease Enzymes

Protease enzymes are the most wide spread microbial

enzymes. They are formed by Aspergillus species. They act

on the interior peptide bonds of proteins and peptides.

Protease enzymes are active in the range of pH 7 to 11

(neutral to alkaline), exhibit maximum activity at a

temperature of 60°C, and are inactive at or above 65°C

(Gerhartz, 1990).

Hemmpel (1991, p.S), has reported that

it is possible to remove skin residues, skin grease and vegetable matters by using protease enzymes. Therefore, the wool surface can be modified with the simultaneous improvement of luster and hand, which is made possible without the chemically and economically questionable chlorinating process.

However, no extensive research has been explored in regard

to the application of protease enzymes.

Summary

Cotton and wool fibers carry natural impurities such as pectin, hemicellulose, lignin, seed husks, vegetable matters, skin grease, suint and skin residue. The removal of these substances by the scouring process generate huge amounts of effluents. However, the use of enzymes has made 24 it possible to replace the scouring process to a limited extent. Cellulase and protease enzymes which are used on

low-grade cotton and wool, respectively, remove the naturally accompanying substances and the protruding loose

fibers, giving an improved hand and a smoother appearance.

The enzyme treatment does not involve conventional

chemicals, thus making it environmentally safe. The

application of cellulase enzymes has been reported; however,

the application of protease enzymes has not been explored.

Therefore, the review of literature is limited in this

regard. CHAPTER III

METHODOLOGY

The methods and procedures used in this study are discussed with regard to the following: {1) description of the experimental fabrics, {2) fabric development procedure,

{3) enzyme treatment on experimental fabrics, {4)physical tests and subjective evaluations, and {5) statistical analysis of data.

Description of the Experimental Fabrics

Three fabrics with different fiber contents of cotton and wool were experimentally developed at the International

Center for Textile Research and Development {ICTRD), Texas

Tech University, Lubbock Texas. The three experimental fabrics are described in Table 3.1.

Fabric Development Procedure

The cotton and wool fibers were obtained from commercial sources. Three experimental fabrics from cotton and wool fibers were manufactured at the ICTRD. Percentage fiber content of the experimental fabrics were: 100% cotton,

90/10 cotton/wool and 70/30 cotton/wool fabrics.

25 Table 3.1

Physical Properties of the Experimental Fibers and Fabrics

Fabric Fabrica Percent Fiber Staple Micronaire Strength Warp Filling Ounces Yarn -tion Fiber Type Length in Yarn Yarn Per Count Content in gms/tex Size Size Square epi X inches Yard ppi*

A Plain 100 Cotton Pima Cotton 1. 28 3.9 33.5 16/1 12/1 6.15 66 X 42 B Plain 90/10 Pima - - - 16/1 12/1 6.15 66 X 42 Cotton/Wool Cotton/Wool c Plain 70/30 Pima - - - 16/1 12/1 6.15 66 X 42 Cotton/Wool Cotton/Wool

~ 0'\ 27

Warp and Filling Yarn Production

In the case of 100% cotton yarn, several cotton fibers were intimately blended and then carded to remove short fibers and leafy matter. The cotton was carded at 75 lbs/hr, producing a sliver of 60 grains/yd. For the cotton/wool blended yarn, both fibers were initially blended and sprayed with an antistatic lubricant before they were carded. The carding production rate was 48 lbs/hr with a sliver of 60 gr/yd. After that juncture, the yarn production procedures remained the same for both 100% cotton and cotton/wool blended yarn. The carded sliver was then drawn on breaker and finisher drawing producing a sliver of

55 gr/yd.

Roving of 1.0 hank was produced from drawn sliver.

Twist was approximately 1.13 turns per inch (t.p.i) with a

spindle speed of 1425 rpm. To spin the warp yarn of Ne

16/1, the spindle speed was 9500 rpm with 15.2 t.p.i and for filling yarn of Ne 12/1, the spindle speed was 8000 rpm with

13.0 t.p.i. The yarns were then wound onto cones at a winding speed of 900 yds/min, and then used to produce the fabric.

Fabric Construction The fabric construction remained the same for all experimental fabrics. Ten back beams, each having 396 ends per beam, were wound at about 200 yds/min. Slashing was at 28 a speed of about 20 yds/min applying a polyvinyl alcohol size with wax, using a squeeze roll pressure of 20 psi.

Weaving was on a 60-inch Sulzer loom. Warp and filling yarns used were bleached and dyed. The construction consisted of four black and four bleached ends with 3 black and 3 bleached picks.

Enzyme Treatment on Experimental Fabrics

The process conditions varied for cellulase and protease enzymes. A brief explanation of the method used to apply enzymes on experimental fabrics follows.

Application of Cellulase Enzymes

Cellulase enzyme was applied on 100% cotton and on cotton/wool blended fabrics, to treat the cotton content of the blended fabric. The experimental fabric was loaded on a jig and was run dry four times around doctor blades to raise the loose fibers to the surface. These blades also ensured a thorough mechanical action throughout the enzyme application process. Next the bath was set with a liquor ratio of 1:10 and the pH was maintained to 4.5 using acetic acid and the temperature of the bath was set to 60°C and the cellulase enzyme was added. The experimental fabric was then treated for one hour maintaining the temperature at

60°C. Finally it was removed and washed in hot water and pad dried at room temperature (Mehta, 1992). 29 Application of Protease Enzymes

Protease enzymes were applied on cotton/wool blended fabrics to treat the wool content of the blended fabric.

The treatment procedure remained the same as the one used for cellulase enzymes with the exception that the pH of the bath was set to 8.5 using dilute sodium hydroxide.

In both of the above treatments, the activity of the enzymes was highly dependent on such factors as pH, temperature and reaction time. The 100% cotton fabric was treated only with cellulase enzyme and the cotton/wool blended fabrics were first treated with cellulase enzymes and the same fabrics were then treated with protease enzymes. Enzymes were applied to the experimental fabrics in two specific concentrations, 3% and 5% on weight by volume basis.

Physical Tests

The procedures of American Society for Testing and

Materials (ASTM, 1991) and the American Association of

Textile Chemists and Colorists (AATCC, 1989) were followed for the physical tests conducted in this study. Physical tests included breaking strength, abrasion resistance, pilling resistance, stiffness, wrinkle recovery and dimensional stability to laundering. An explanation of test methods, instruments used, sample descriptions and purpose are listed in Table 3.2. Subjective evaluation was used to Table 3.2

Description of Physical Tests

Test Method Physical Test Instrument Sample No of Purpose Used Size Samples** (inches) ASTM Breaking Instron 1 X 8 10 To determine the breaking strength, D 1682-7S Strength i.e. the force required to rupture specific wirlth of fabric. ASTM Abrasion Universal 1.2S X 8 10 To determine the resistance of samples D 388S-80 Resistance Wear Tester to flexing and abrasion.

AATCC Dimensional Sears Kenmore 10 X 10 OS To determine the dimensional changes 13S-1987 Stability Washer and in the length and width of the fabric. Drier ASTM Fabric Drape-Flex 1 X 6 10 To assess the resistance to bending, a D 1388-7S Stiffness Stiffness property that is directly associated Tester with fabric hand.

AATCC Wrinkle Wrinkle 1.S X 4* 10 To assess the wrinkle recovery, a 66-1984 Recovery Recovery property that predicts the resiliency Tester of the fabric. ASTM Pilling Random Tumble 4 X 4 OS To determine resistance to the D 3S12-82 Resistance Pilling bending, a property that is directly Tester associated with fabric hand.

* in em ** each in warp and filling directions for all experimental fabrics

w 0 31 determine the fabric hand and pilling rating. A 5-point

Likert scale was used to assess the fabric hand (refer

Figure 3.1). Also a Scanning Electron Microscope was used exclusively to study the surface properties of treated and untreated fabrics. All of the above physical and subjective tests were carried out at the ICTRD. The Scanning Electron

Microscope used was located in the Department of Biology,

Texas Tech University.

All the physically tested samples were subjected to standard conditions of 70° ± 2° F and a constant relative humidity of 65 ± 2% for twenty-four hours before testing.

Standard conditions were not necessary for Scanning Electron

Micrography.

Test for Breaking Strength

ASTM D 1682 - 75 Standard Test Methods for Breaking

Load and Elongation of Textile Fabrics (ASTM, 1991) was used to determine breaking strength. All samples were initially cut to a width of 1.5 inches and then unravelled to an exact width of 1 inch. Ten 1 X 8 samples in warp and filling directions were tested to determine effective strength of yarns using ravelled strip method. The Instron Tester

(Model TM-S), a constant-rate-of-extension machine, was used to report strength in pounds. 32

Instructions: Please feel the fabric samples and rank each one from very soft to rough, using the range from 1 to 5.

1 2 3 4 5 Very Soft Moderately Moderately Rough Soft Soft Rough

Fabric 1

Fabric 2

Fabric 3

Fabric 4

Fabric 5

Fabric 6

Fabric 7

Fabric 8

Fabric 9

Figure 3.1 Rating Scale Score Sheet 33 Test for Abrasion Resistance

ASTM D 3885 - 80 Standard Test Method for Abrasion

Resistance of Textile Fabrics (ASTM, 1991) was utilized to determine the resistance of woven fabrics to flexing and abrasion. All samples were initially cut to a width of 1.25

inches and then unravelled to 1 inch. Ten 1 X 8 samples in warp and filling directions for all experimental fabrics were tested on Universal Wear Tester (Model #CS-22C) using

flexing and abrasion method. The results were reported in a number of cycles.

Test for Dimensional Stability to Laundering

AATCC 135-1987 Test Method for Dimensional Changes in

Automatic Home Laundering of Woven and Knit fabrics (AATCC,

1991), was used to determine dimensional changes. Five 10 X

10 samples were washed in a Sears Kenmore Advantage Washer

(Model #110.92273100) using a normal washing cycle for five

times. The samples were dried in a Sears Kenmore Advantage

Drier (Model #110.96274100) using a tumble drying setting.

Dimensional changes were noted after the first and fifth washes and reported in the form of percentage shrinkage.

Test for Fabric Stiffness ASTM D 1388 - 75 Standard Test Method for Stiffness of

Fabrics (ASTM, 1991) was used to assess the flexural rigidity, a measure of stiffness. Ten 1 X 6 samples in warp 34 and filling directions were tested both on face and back side on Drape-Flex Stiffness Tester. Flexural rigidity was reported in milligram-centimeters.

Test for Wrinkle Recovery

AATCC 66-1984 Test Method for Wrinkle Recovery {AATCC,

1989) was used to determine wrinkle recovery of experimental fabrics. Ten 1.5 X 4.0 ern fabric samples in warp and filling directions were measured using Recovery Angle

Method, on a Monsanto Wrinkle Recovery Tester. Average warp and filling recovery was reported in degrees as well as percentage recovery.

Test for Pilling Resistance

ASTM D 3512 - 82 Standard Test Method for Pilling

Resistance and other Related Surface Changes of Textile

Fabrics {ASTM, 1991) was used to determine the resistance to the formation of pills. This method utilized an Atlas

Random Tumble Pilling Tester {Model #PP-428). Five 4 X 4 samples of experimental fabrics were tested for 1 hour. The samples were rated by comparison to actual photographs showing a range of pilling effects by a panel.

Fabric Hand

A subjective evaluating method was used to determine the hand {softness) of treated and untreated experimental 35 fabrics. The evaluation panel was comprised of Textile

Testing Personnel of ICTRD. Five panel members with extensive knowledge of various textile testing procedures were selected to evaluate the hand of the specimens.

The members felt each specimen independently and then rated them on a Likert scale from one to five, one indicating a very soft hand and five a rough hand. The rating scale score sheet is shown in Table 3.3.

Scanning Electron Microscope

Both treated and untreated fabric samples were viewed under the scanning electron microscope to uncover the effect of treatment on the surface appearance. Specimen preparation included selecting samples randomly from different areas of treated and untreated fabrics. The specimens were mounted on a stub on a double sided carbon conductive tape and grounded using colloidal silver paste. They were then coated with a thin layer (about 300 A) of gold/palladium alloy in a Technics Hummer V sputter coater.

This process helped to generate secondary electrons necessary for the signal. Samples were then examined under a Hitachi S-570 scanning electron microscope using an accelerating potential of 8 kV. Electron micrographs were taken using a 35mm Nikon Camera with a 100 second exposure and developed using Dektol D-72 developer. 36

Analysis of Data

The data obtained from physical testing of three experimental fabrics were statistically analyzed in the following manner.

As a preliminary assessment, means and standard deviations of breaking strength, fabric stiffness, abrasion resistance, pilling resistance, dimensional stability, and wrinkle recovery were reported for descriptive purpose.

One-way analysis of variance was used to determine whether or not there were any significant differences between the treatment levels of each fiber content groups for above mentioned tests. A level of significance equal to 0.05 was used. Tukey's studentized range (HSD) test was used to assess where any differences existed. For subjective evaluation, Pearson's r correlation coefficient, an inter judge measure among the five judges, was reported. CHAPTER IV

ANALYSIS OF DATA

The data for the study were obtained by conducting physical tests, following ASTM and AATCC standards, and by means of subjective evaluation. The purpose of the study was to obtain and treat the cotton and cotton/wool blended fabrics with cellulase and protease enzymes; and to assess the surface appearance and selected physical properties of treated and untreated fabrics.

Data were analyzed to determine the effects of enzyme treatment on experimental fabrics. Results of the study are reported in the following sections: (a) description of sample, (b) analysis of hypotheses, and (c) summary of data analysis.

Description of Sample

For this study, the population was three experimental fabrics made from cotton and wool fibers. The fiber content of the experimental fabrics were: 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool.

Pima cotton and wool fibers were obtained from commercial sources for the production of experimental fabrics. A total of 200 yards in each variety was experimentally developed in plain weave at the International

37 38 Center for Textile Research and Development (ICTRD), Texas

Tech University, Lubbock, Texas.

A sample of 20 yards in each experimental fabrics was

selected for enzyme treatments. Random sampling technique was used to select samples for each physical test to ensure

that no two samples contained the same warp and filling yarns. Hence, the sample selected were a true

representative of the population and ceased to be biased

sample. Sample size varied depending upon the nature of the

physical test used.

Analysis of Hypotheses

Three hypotheses were proposed for the study. Data

were statistically analyzed for application to the specific

hypotheses using the Statistical Application Software (SAS) .

Means, standard deviations, and one-way analysis of variance

(ANOVA) were used for analysis of Hypothesis 1. Hypothesis

2 was analyzed using means, standard deviations, one-way analysis of variance, and a Pearson's r correlation statistic. Hypothesis 3 was analyzed using means, standard deviations and Pearson's r correlation statistic.

The means and standard deviations allowed comparisons of treated and untreated fabrics at 3% and 5% treatment levels. ANOVA was used to compare treated and untreated groups to determine whether a significant differences existed between mean scores. A significant difference would 39 indicate the two groups do not have the same mean. When

post hoc tests were required to determine which groups

exhibited different means, the Tukey's studentized range

test was used. The Tukey's test is more powerful for

comparing pair of means (Shavelson, 1988). Pearson's r

correlation statistic was used to determine Interjudge Reliability.

Hypothesis 1.a

There are no significant differences in the physical

test results for treated and untreated cotton and

cotton/wool blended fabrics with regard to:

breaking strength in warp and filling directions.

Data used to analyze this hypothesis were obtained by

testing the treated and untreated fabric samples on the

Instron Tester. The breaking strength of warp and filling

was reported in pounds per square inch. Table 4.1 shows the mean and standard deviations of breaking strength for

experimental fabrics in warp and filling direction. Table

4.2 and Figure 4.1 show the percentage strength loss after enzyme application at both treatment levels.

As indicated by Table 4.1, the mean breaking strength declined continuously at 3% and 5% treatment levels, in both warp and filling directions. The warp strength was found to be higher compared to filling. One hundred percent cotton fabrics had higher breaking strength than 90/10 and 70/30 40

Table 4.1

Means and Standard Deviations of Breaking Strength ( lbs.) in Warp and Filling Directions

Percent Warp Warp Filling Filling Fiber Before After Before After Content Mean SD Mean SD Mean SD Mean SD 3t Treatment lOOt Cotton 93.80 2.38 83.05 3.54 86.75 5.52 75.85 3.38 90/10 Cotton/Wool 73.80 5.07 65.00 2.87 63.80 2. 94 59.10 3.09

70/30 Cotton/Wool 68.75 1.32 59.00 3.74 58.35 3.02 49.40 4.34

5t Treatment lOOt Cotton 93.80 2.48 80.22 5.76 86.75 5.52 74.60 2.28 90/10 Cotton/Wool 73.80 5.07 60.65 4.98 68.30 4.45 56.10 2.72 70/30 Cotton/Wool 68.75 1.32 56.35 2.97 58.35 3.02 48.00 3.07 41 Table 4.2 Percentage Strength Loss After Enzyme Treatments

Warp Filling Average 3% Treatment 100% Cotton 11.46 12.56 12.01 90/10 Cotton/Wool 11.92 13.47 12.69 70/30 Cotton/Wool 14.18 15.34 14.76

5% Treatment 100% Cotton 14.49 14. 01· 14.24 90/10 Cotton/Wool 17.82 17.86 17.84 70/30 Cotton/Wool 18.02 17.74 17.88 42

1 8 1 6

-- -=CD ~ tl)- ~

5% Treaanent

=0 - 3% Treaanent 8 -8 ~ ~ -8 8 =0 - -0 ~c u 0 0 -0 -~ u 0\ 0 ~ ~ r--

Figure 4.1 Percentage Strength Loss 43 cotton/wool blended fabrics. Fabrics treated with 3% enzymes retained more strength than those treated with 5% enzymes.

A one-way analysis of variance of breaking strength in warp and filling directions, for 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool fabrics is shown in Tables

4.3 and 4.4. The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics. When significant F ratios resulted from the ANOVA tests, the Tukey's studentized range test was used to identify the existence of significant differences between groups. This post hoc comparison revealed differences between control and 3% treated fabric and control and 5% treated fabric. However there was no significant difference between 3% and 5% treated experimental fabrics with regard to breaking strength.

Since significant differences were found between control and treated fabrics, Hypothesis 1.a was rejected.

Hypothesis 1.b There are no significant differences in the physical

test results for treated and untreated cotton and

cotton/wool blended fabrics with regard to:

abrasion resistance in warp and filling

directions.

Data used to analyze this hypothesis were obtained by --~~------~- ---~--- -

44 Table 4.3 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Breaking Strength in Warp Direction

Source of Variance ss df MS F Sig. of F lOOt Cotton Between Groups 1054.73 2 527.36 29.77 0.0001* Within Groups 496.01 27 17.71 90/10 Cotton/Wool Between Groups 897.62 2 404.13 22.86 0.0001* Within Groups 530.13 27 19.63 70/30 Cotton/Wool Between Groups 852.82 2 426.41 51.94 0.0001* Within Groups 221.65 27 8.21

Treatment Level Control Jt Treatment 5% Treatment

Mean (lOOt Cotton) 93.80 83.05 80.22

Mean (90/10 Cotton/Wool) 73.80 65.00 60.55 Mean (70/30 Cot ton Wool) 68.75 59.00 56.35

Results of Tukey's studentized range test results are reported by underline method. A line appears beneath groups that do not differ significantly from each other. Thus, groups not underlined by the same line or lines at the same level are significantly different from each other.

* Indicates significance at 0.05 probability level. 45 Table 4.4 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Breaking Strength in Filling Direction

Source of Variance ss df MS F Sig. of F 100\ Cotton

Between Groups 893.32 2 446.66 28.41 0.0001* Within Groups 424.55 27 17.71 90/10 Cotton/Wool Between Groups 808.27 2 404.13 47.36 0.0001* Within Groups 230.40 27 8.53 70/30 Cotton/Wool Between Groups 423.95 2 211.97 16.96 0.0001* Within Groups 337.42 27 12.50

Treatment Level Control 3\ Treatment 5\ Treatment

Mean (100\ Cotton) 86.75 75.85 74.60

Mean (90/10 Cotton/Wool) 68.30 59.10 56.10

Mean (70/30 Cotton Wool) 58.35 49.40 48.00

* Indicates significance at 0.05 probability level. 46 subjecting the treated and untreated fabric samples to a unidirectional rubbing action over a flexing bar on a

Universal Wear Tester. The abrasion resistance of warp and filling was reported in the nearest 10 cycles. Table 4.5 provides the mean and standard deviations of abrasion resistance for experimental fabrics in warp and filling direction. Table 4.6 and Figure 4.2 show the percentage loss abrasion resistance after enzyme application at both treatment levels.

As indicated by Table 4.5, the cotton/wool blended fabrics were more resistant to abrasion than 100% cotton fabrics. The mean abrasion resistance declined continuously at 3% and 5% treatment levels, in both warp and filling direction. The warp abrasion resistance was found to be higher compared to filling. One hundred percent cotton fabrics showed comparatively less loss. Fabrics treated with 5% enzymes were more resistant to abrasion than those treated with 3% enzymes.

A one-way analysis of variance of abrasion resistance in warp and filling directions, for 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool fabrics is shown in Tables

4.7 and 4.8. The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics. When significant F ratios resulted from the ANOVA tests, the Tukey's studentized range test was used to identify the existence of significant differences 47

Table 4.5

Means and Standard Deviations of Abrasion Resistance{cycles) in Warp and Filling Directions

Percent Warp Warp Filling Filling Fiber Before After Before After Content Mean SD Mean SD Mean SD Mean SD 3t Treatment lOOt Cotton 315 33.29 195 26.77 430 37.90 235 23.10 90/10 Cotton/Wool 1005 79.00 425 60.47 1120 69.75 515 44.82

70/30 Cotton/Wool 1155 52.37 500 20.89 1210 63.35 855 53.07

5t Treatment lOOt Cotton 315 33.29 295 25.04 430 59.42 261 60.37 90/10 Cotton/Wool 1005 79.00 430 22.09 1120 69.75 550 47.63 70/30 Cotton/Wool 1155 52.37 650 44.46 1210 63.35 700 38.64 48 Table 4.6 Percentage Loss in Abrasion Resistance After Enzyme Treatments

Warp Filling Average 3t Treatment lOOt Cotton 38.09 45.35 41.72 90/10 Cotton/Wool 57.71 54.02 55.87 70/30 Cotton/Wool 56.70 29.34 43.02

5t Treatment lOOt Cotton 06.35 39.30 22.83 90/10 Cotton/Wool 57.21 50.89 54.05 70/30 Cotton/Wool 43.72 42.15 42.94 49

3% Treatment

100% Couon 5% Tre3unent 90/10 Cotton/Wool 70/30 Couon/W ool

Figure 4.2 Percentage Loss in Abrasion Resistance so Table 4.7 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Abrasion Resistance in Warp Direction

Source of Variance ss df MS F Sig. of F lOOt Cotton Between Groups 103740.00 2 51870.00 55.99 0.0001* Within Groups 25013.50 27 926.46 90/10 Cotton/Wool Between Groups 2236572.47 2 1118286.23 322.55 0.0001* Within Groups 93610.50 27 3467.05 70/30 Cotton/Wool Between Groups 2351140.47 2 1175570.23 684.02 0.0001* Within Groups 46402.90 27 1718.62

Treatment Level Control 3t Treatment 5t Treatment

Mean (lOOt Cotton) 315 195 295

Mean (90/10 Cotton/Wool) 1005 425 430

Mean (70/30 Cot ton Wool) 1155 500 650

* Indicates significance at 0.05 probability level. 51 Table 4.8 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Abrasion Resistance in Filling Direction

Source of Variance ss df MS F Sig. of F 100% Cotton Between Groups 190125.60 2 95062.80 100.43 0.0001* Within Groups 25557.19 27 946.80 90/10 Cotton/Wool Between Groups 2287056.86 2 1143528.43 375.28 0.0001* Within Groups 83371.80 27 3047.10 70/30 Cotton/Wool Between Groups 1349738.87 2 674869.43 243.32 0.0001* Within Groups 74887.00 27 2773.59

Treatment Level Control 3% Treatment 5% Treatment

Mean (100%' Cotton) 430 335 235

Mean (90/10 Cotton/Wool) 1120 515 550

Mean (70/30 Cotton Wool) 1210 855 700

* Indicates significance at 0.05 probability level. 52 between groups. This post hoc comparison revealed

differences between control and 3% treated fabric and

control and 5% treated fabric. However there was no

significant difference between 3% and 5% treated

experimental fabrics for 90/10 cotton/wool blended fabrics

with regard to breaking strength. Since significant

differences were found between control and treated fabrics, Hypothesis 1.b was rejected.

Hypothesis 1.c

There are no significant differences in the physical

test results for treated and untreated cotton and

cotton/wool blended fabrics with regard to:

dimensional stability in warp and filling

directions.

Data used to analyze this hypothesis were obtained by

measuring the shrinkage of treated and untreated fabric in

warp and filling direction. Measurements were taken after 1

and 5 laundering periods. The dimensional stability was

reported in inches. Table 4.9 provides the mean and

standard deviations of dimensional stability for experimental fabrics in warp direction. Table 4.10 and

Figures 4.3 and 4.4 show the percentage shrinkage after 1 and 5 laundering periods at both treatment levels.

As indicated by Table 4.9, the general order of shrinkage in the warp direction was 100% cotton < 90/10 53

Table 4.9

Means and Standard Deviations of Dimensional Stability (inches) in Warp Direction

Percent Warp Warp Filling Filling Fiber Before After Before After Content Mean SD Mean SD Mean SD Mean SD 3\' Treatment 100\' Cotton 10.03 0.07 09.32 0.12 10.03 0.07 08.94 0.07 90/10 Cotton/Wool 09.96 0.07 09.36 0.05 09.96 0.07 09.12 0.08

70/30 Cotton/Wool 10.03 0.05 09.43 0.07 10.03 0.05 09.11 0.08

5\' Treatment 100\' Cotton 10.04 0.05 09.32 0.09 10.04 0.05 09.00 0.11 90/10 Cotton/Wool 10.01 0.06 09.30 0.16 10.01 0.06 09.02 0.16 70/30 Cotton/Wool 10.02 0.06 09.33 0.17 10.02 0.06 09.04 0.16 54 Table 4.10 Percentage Shrinkage in Warp Direction After Enzyme Treatments

Warp Warp (one wash) (five wash) 3% Treatment 100% Cotton 7.08 10.87

90/10 Cotton/Wool 6.02 8.52

70/30 Cotton/Wool 5.98 9.17

5% Treatment 100% Cotton 7.17 10.35

90/10 Cotton/Wool 7.09 9.89

70/30 Cotton/Wool 6.89 9.79 55

5% Treaanent c 0 - 3% Treatment -0 -0 u 0 ~ - ~c 8 8 0 ~ - -0 c u 0 0 - 0'- 8 0 0\ M 0' l"'-

Figure 4.3 Percentage Shrinkage After One Wash 56

5% Treatment c 0 - 3% Treatment 8- -8 ~ ~ -0 8 c 0 0 ~ - -0 c c..> 0 0 -0 - c..> 0' 0 0\ ("f"') 0 r-

Figure 4.4 Percentage Shrinkage After Five Washes 57 cotton/wool < 70/30 cotton/wool blended fabrics. 3% treated, 100% cotton fabrics showed the greatest amount of dimensional change at 1 and 5 laundering periods. When the dimensional change of the blended fabrics was compared, it was found that 70/30 cotton/wool blended fabrics displayed higher degree of dimensional stability than did 90/10 cotton/wool blend. A comparison of the degree of dimensional changes occurring after 1 and 5 washes revealed that the major differences were found as a function of enzyme treatments. The dimensional stability in the filling direction remained constant for all experimental fabrics, hence the results were not reported.

A one-way analysis of variance of dimensional stability in warp direction, for 100% cotton, 90/10 cotton/wool and

70/30 cotton/wool fabrics is shown in Tables 4.11 and 4.12.

The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics. When significant F ratios resulted from the ANOVA tests, the Tukey's studentized range test was used to identify the existence of significant differences between groups. This post hoc comparison revealed differences between control and 3% treated fabric and control and 5% treated fabric. Also, significant differences were found between 3% and 5% treated experimental fabrics. Therefore,

Hypothesis 1.c was rejected. 58 Table 4.11 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Dimensional Stability in Warp Direction with 3% Treatment

Source of Variance ss df MS F Sig. of F lOOt Cotton

Between Groups 5.50 2 2.75 333.84 0.0001* Within Groups 0.19 24 0.01 90/10 Cotton/Wool Between Groups 3.39 2 1.69 352.92 0.0001* Within Groups 0.11 24 0.01 70/30 Cotton/Wool Between Groups 3.94 2 1. 97 434.53 0.0001* Within Groups 0.11 24 0.01

Treatment Level Control 3% Treatment 5% Treatment

Mean (lOOt Cotton) 10.03 9.32 8.94

Mean (90/10 Cotton/Wool) 9.96 9. 36 9.12

Mean (70/30 Cotton Wool) 10.03 9.43 9.11

Table 4.12

One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Dimensional Stability in Warp Direction with 5% Treatment

Source of Variance ss df MS F Sig. of F lOOt Cotton

Between Groups 5.15 2 2.57 312.40 0.0001* Within Groups 0.19 24 0.01 90/10 Cotton/Wool

Between Groups 4.68 2 2.34 120.98 0.0001* Within Groups 0.46 24 0.02 70/30 Cotton/Wool Between Groups 4.54 2 2.27 114.08 0.0001* Within Groups 0.48 24 0.02

Treatment Level Control 3t Treatment 5% Treatment

Mean (lOOt Cotton) 10.04 9.32 9.00

Mean (90/10 Cotton/Wool) 10.01 9.30 9.02

Mean (70/30 Cotton Wool) 10.02 9.33 9.04

* Indicates significance at 0.05 probability level. 60 Hypothesis 1.d

There are no significant differences in the physical

test results for treated and untreated cotton and

cotton/wool blended fabrics with regard to: fabric

stiffness in warp and filling directions.

Data used to analyze this hypothesis were obtained by testing the treated and untreated fabric samples on Drape flex Stiffness Tester. The bending length (c), which is a measure of interaction between fabric weight and fabric stiffness, was measured in centimeters. Then, the flexural rigidity (G) was calculated using the following formula:

3 Flexural rigidity, G = w X c , where w = weight per

2 unit area, ln mg/cm • Table 4.13 provides the mean and standard deviations of fabric stiffness for experimental fabrics in warp and filling directions. Table 4.14 and

Figure 4.5 show the overall flexural rigidity (which is the geometric mean of warp and filling flexural rigidity) .

As indicated by Table 4.13, the cotton/wool blended fabrics were less stiffer than 100% cotton fabrics.

Compared to other fabrics, 70/30 cotton/wool blended fabrics were least stiff in the warp and filling directions. The mean fabric stiffness declined continuously at 3% and 5% treatment levels, in both warp and filling directions. The warp stiffness was found to be higher compared to filling.

A one-way analysis of variance of fabric stiffness in warp and filling directions, for 100% cotton, 90/10 61

Table 4.13 Means and Standard Deviations of Fabric Stiffness in Warp and Filling Directions

Percent Warp Warp Filling Filling Fiber Before After Before After Content Mean SD Mean SD Mean SD Mean SD 3\' Treatment

100\' Cotton 5.09 0.27 4.26 0.20 4.99 0.13 4.12 0.12 90/10 Cotton/Wool 4.53 0.21 3.52 0.14 3.99 0.11 3.69 0.19 70/30 Cotton/Wool 4.68 0.39 3.45 0.22 4.20 0.15 3.43 0.18

5\' Treatment 100\' Cotton 5.09 0.27 3.94 0.11 4.99 0.13 4.11 0.19 90/10 Cotton/Wool 4.53 0.21 3.41 0.19 3.99 0.11 3.46 0.18 70/30 Cotton/Wool 4.68 0.39 3.46 0.16 4.20 0.15 3.42 0.20 62 Table 4.14

Overall Flexural Rigidity After Enzyme Treatments

Flexural Rigidity Control

100% Cotton 305.73

90/10 Cotton/Wool 205.53

70/30 Cotton/Wool 180.75

3% Treatment 100% Cotton 168.06 90/10 Cotton/Wool 103.99 70/30 Cotton/Wool 090.63

5% Treatment 100% Cotton 146.68 90/10 Cotton/Wool 090.07 70/30 Cotton/Wool 089.89 63

350

300

~ ·-""0- ·-CJ) ·-0::

3% Treatment c -0 8- -8 5% Treatment ~ 8 8 ~0 - - ~ 8- 0 0 - - 8- 0\o- 0 ~

f'o-

Figure 4.5 Fabric Stiffness 64 cotton/wool and 70/30 cotton/wool fabrics is shown in Tables

4.15 and 4.16. The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics. When significant F ratios resulted from the ANOVA tests, the Tukey's studentized rangetest was used to identify the existence of significant differences between groups. This post hoc comparison revealed differences between control and 3% treated fabric and control and 5% treated fabric. However there was no significant difference between 3% and 5% treated experimental fabrics with regard to fabric stiffness. Since significant differences were found between control and treated fabrics, Hypothesis 1.d was rejected.

Hypothesis l.e There are no significant differences in the physical

test results for treated and untreated cotton and

cotton/wool blended fabrics with regard to:

wrinkle recovery in warp and filling directions.

Data used to analyze this hypothesis were obtained by testing the treated and untreated fabric samples on Monsanto

Wrinkle Recovery Tester. The wrinkle recovery was reported to the nearest degree. Table 4.17 provides the mean and standard deviations of wrinkle recovery for experimental fabrics in warp and filling directions. Table 4.18 and

Figure 4.6 show the recovery from wrinkle in degrees. 65

Table 4.15

One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Fabric Stiffness in Warp Direction

Source of Variance ss df MS F Sig. of F 100% Cotton Between Groups 14.19 2 7.09 164.20 0.0001* Within Groups 2.46 57 0.04 90/10 Cotton/Wool Between Groups 15.24 2 7.62 234.59 0.0001* Within Groups 1. 85 57 0.03 70/30 Cotton/Wool Between Groups 20.00 2 10.00 129.31 0.0001* Within Groups 4.41 57 0.08

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 5.90 4.26 3.94

Mean (90/10 Cotton/Wool) 4.53 3.52 3.41

Mean (70/30 Cotton Wool) 4.68 3.45 3.46

Table 4.16

One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Fabric Stiffness in Filling Direction

Source of Variance ss df MS F Sig. of F 100% Cotton Between Groups 10.09 2 5.05 221.10 0.0001* Within Groups 1. 30 57 0.02 90/10 Cotton/Wool Between Groups 2.77 2 1.38 49.56 0.0001* Within Groups 1. 59 57 0.03 70/30 Cotton/Wool Between Groups 7.96 2 3.97 126.02 0.0001* Within Groups 1. 79 57 0.03

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 4.99 4.12 4.11

Mean (90/10 Cotton/Wool) 3.99 3.69 3.46

Mean (70/30 Cotton Wool) 4.20 3.43 3.42

* Indicates significance at 0.05 probability level. 67

Table 4.17 Means and Standard Deviations of Wrinkle Recovery (degrees) in Warp and Filling Directions

Percent Warp Warp Filling Filling Fiber Before After Before After Content Mean SD Mean SD Mean SD Mean SD 3t Treatment lOOt Cotton 075.10 3.84 081.30 3.62 064.00 4.85 088.70 2.41 90/10 Cotton/Wool 101.80 3.55 103.60 3.83 096.30 3.88 107.30 3.12 70/30 Cotton/Wool 108.80 4.23 117.90 3.03 106.50 5.12 119.20 2.30

5t Treatment lOOt Cotton 075.10 3.84 081.80 4.34 064.00 4.85 088.30 3.97 90/10 Cotton/Wool 101.80 3.55 099.00 4.16 096.30 3.89 101.90 3.87 70/30 Cotton/Wool 108.80 4.23 118.00 2.36 106.50 5.12 119.90 2.56 68

Table 4.18

Wrinkle Recovery in Degrees in Warp and Filling Directions After Enzyme Treatments

Warp Filling

3% Treatment 100% Cotton 6.20 24.00

90/10 Cotton/Wool 1.80 11.00

70/30 Cotton/Wool 9.10 12.70

5% Treatment 100% Cotton 6.70 24.30

90/10 Cotton/Wool 5.60

70/30 Cotton/Wool 9.20 13.40 69

120

5% Treatment

3% Treatment c 0 -0 u- 8 Conttol ~ ~ 8 c 8 - 0 -0 u ~0 0 .... -0 - u & 0

~r""'-

Figure 4.6 Wrinkle Recovery in Degrees 70 As indicated by Table 4.17, the cotton/wool blended

fabrics recovered to a greater extent compared to 100%

cotton fabrics. The wrinkle recovery was found to be higher

in filling direction compared to warp.

A one-way analysis of variance of wrinkle recovery ln warp and filling directions, for 100% cotton, 90/10

cotton/wool and 70/30 cotton/wool fabrics is shown in Tables

4.19 and 4.20. The results of the ANOVA disclosed that

there was a highly significant interaction between control

and enzyme treated fabrics with the exception control and

90/10 cotton/wool blended fabrics in warp direction. When

significant F ratios resulted from the ANOVA tests, the

Tukey's studentized range test was used to identify the

existence of significant differences between groups. This post hoc comparison revealed differences between control and

3% treated fabric and control and 5% treated fabric.

However there was no significant difference between 3% and

5% treated experimental fabrics with regard to wrinkle recovery. Since significant differences were found between control and treated fabrics, Hypothesis 1.e was rejected.

Hypothesis 2

There are no significant differences in the surface

appearance of the treated and untreated cotton and

cotton/wool blended fabrics with regard to pill

formation. 71

Table 4.19

One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Wrinkle Recovery in Warp Direction

Source of Variance ss df MS F Sig. of F 100% Cotton

Between Groups 278.60 2 139.30 8.94 0.0001* Within Groups 420.60 27 15.58 90/10 Cotton/Wool Between Groups 107.47 2 53.73 3.61 0.0408* Within Groups 402.00 27 14.88 70/30 Cotton/Wool Between Groups 558.20 2 279.10 25.59 0.0001* Within Groups 294.50 27 10.90

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 75.10 81.30 81.80

Mean (90/10 Cotton/Wool) 101.80 103.60 99.00

Mean (70/30 Cotton Wool) 108.80 117.90 118.00

* Indicates significance at 0.05 probability level. 72 Table 4.20 One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Wrinkle Recovery in Filling Direction

Source of Variance ss df MS F Sig. of F 100% Cotton

Between Groups 4002.47 2 2001.23 133.02 0.0001* Within Groups 406.20 27 15.04 90/10 Cotton/Wool Between Groups 605.07 2 302.53 22.75 0.0001* Within Groups 359.10 27 13.30 70/30 Cotton/Wool Between Groups 1137.80 2 568.90 44.78 0.0001* Within Groups 343.00 27 12.70

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 64.00 88.70 88.30

Mean (90/10 Cotton/Wool) 96.30 107.30 101.90

Mean (70/30 Cotton Wool) 106.50 119.20 119.90

* Indicates significance at 0.05 probability level. 73 Data used to analyze this hypothesis were obtained by

testing the treated and untreated fabric samples on Random

Tumble Pilling Tester. The samples were then rated utilizing the ASTM Photographic Pilling Standards. The

rating was based on a 1 to 5 scale, with a 1 being severe

pilling and a 5 being no pilling. Table 4.21 provides the mean and standard deviations of pilling resistance of

experimental fabrics.

As indicated by Table 4.21 and Figure 4.7, the pill

ratings for untreated fabrics were higher than the ratings

for treated fabrics. The untreated 70/30 cotton/wool blend

fabric was rated the lowest, with a 2.8, where as the 100%

cotton and 90/10 cotton/wool blended fabrics received 3.0

each. Experimental fabrics treated with 3% and 5% enzymes

received a 5.0 rating, indicating no pilling.

A panel of 5 judges were instructed to rate the

experimental fabrics for pilling resistance. The fabrics were rated according to the ASTM Photographic Pilling

Standards. The rating was based on a 1.0 to 5.0 scale, with

5.0 being no pilling and a 1.0 being very severe pilling.

The reliability coefficient for the rating scale of the pilling specimens was analyzed by Cronbach's alpha

(Cronbach, 1951). The alpha was found to be 0.84. The ratings of panel judges were compared for interjudge reliability using Pearson's r correlation analysis. Table

4.22 shows correlation among judges. From these readings, 74

Table 4.21

Means and Standard Deviations of Pilling Resistance

Percent Fiber Content Before After Mean SD Mean SD 3% Treatment

100% Cotton 3.00 0.00 5.00 0.00 90/10 Cotton/Wool 3.00 0.00 5.00 0.00 70/30 Cotton/Wool 2.80 0.45 5.00 0.00

5% Treatment 100% Cotton 3.00 0.00 5.00 0.00 90/10 Cotton/Wool 3.00 0.00 5.00 0.00 70/30 Cotton/Wool 2.80 0.45 5.00 0.00 75

5 4.5 4

c~ ·-= ~

5% Treatment

3% Treatment c -0 8- 8 ~ ~c 8 8 0 - - ~ 8- 0 0 -0 - (.) 0 0 0\ M 0 r-

Figure 4.7 Pilling Resistance 76 Table 4.22 Interjudge Reliability of Pilling Ratings (Pearson Correlation Coefficients)

Judge 1 Judge 2 Judge 3 Judge 4 Judge 5

Judge 2 1.00 Judge 3 0.97 0.97 Judge 4 1.00 1.00 0.97 Judge 5 1.00 1.00 0.97 1.00 1.00 77 it can be concluded that judges were highly consistent in their ratings.

The above results are further supported by means of scanning electron micrographs. An explanation of which is given below:

Scanning Electron Microscope Results of Surface Appearance

The surface appearance of the treated and untreated fabrics was determined by examination utilizing a Hitachi s- 570 Scanning Electron Microscope (SEM) . The samples from experimental fabrics were obtained using random sampling techniques. Scanning electron micrographs showing untreated and treated 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool fabrics are presented in Figures 4.8, 4.9 and

4.10, respectively. SEM examination revealed a considerable improvement in the fabric's surface. As seen from the micrographs, most of the loose microfibrils which were protruding in untreated fabrics were absent in treated fabrics. A one-way analysis of variance of pilling resistance, for 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool fabrics is shown in Table 4.23. The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics. When significant F ratios resulted from the ANOVA tests, the Figu e 4.

SE 'so 100% Co on J:"lCS: ( ) % T ea e (c 5% T1

Figure 4.10

SEM's o 70/30 Co on/Wool F brics: ( ) Un r e ' (b) % T ea e n (c) 5% T 81

Table 4.23

One-Way ANOVA and Tukey's Studentized Range Test Results- Influence of Fiber Content on Pilling Resistance

Source of Variance ss df MS F Sig. of F 100% Cotton

Between Groups 13.33 2 6.67 9999.99 0.0001* Within Groups 0.00 12 0.00 90/10 Cotton/Wool Between Groups 13.33 2 6.67 9999.99 0.0001* Within Groups 0.00 12 0.00 70/30 Cotton/Wool Between Groups 16.13 2 8.07 121.00 0.0001* Within Groups 0.80 12 0.07

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 3.00 5.00 5.00

Mean (90/10 Cotton/Wool) 3.00 5.00 5.00

Mean (70/30 Cotton Wool) 2.80 5.00 5.00

* Indicates significance at 0.05 probability level. 82 Tukey's studentized range test was used to identify the existence of significant differences between groups. This post hoc comparison revealed differences between control and

3% treated fabric and control and 5% treated fabric. Also, significant differences were found between 3% and 5% treated experimental fabrics. Therefore, Hypothesis 2 was rejected.

Hypothesis 3

There are no significant differences in subjective evaluation of the treated and untreated cotton and cotton/wool blended fabrics with regard to fabric hand.

Data used to analyze this hypothesis were obtained by subjective evaluation of the treated and untreated fabric samples. A panel of 5 judges were instructed to feel the samples and rank them from very soft to rough using a 1.0 to

5.0 Likert scale. The reliability coefficient of the Likert scale was reported using Cronbach's coefficient alpha. The alpha was found to be 0.83. The high alpha rating confirmed the consistency of the scale. Table 4.24 shows the means and standard deviations of experimental fabrics. From Table

4.24, it can be seen that the untreated fabrics were rated high, where as both treated groups were rated low.

The ratings of 5 panel judges were compared for interjudge reliability using Pearson's r correlation analysis. Table 4.25 shows the correlation among judges. 83 Table 4.24 Means and Standard Deviations of Fabric Hand

Mean S.D Untreated lOOt Cotton 5.0 0.00 90/10 Cotton Wool 4.2 0.46 70/30 Cotton/Wool 4.0 0.00

3t Treated lOOt Cotton 1.6 0.49 90/10 Cotton/Wool 2.0 0.63 70/30 Cotton/Wool 1.8 0.40

5t Treated lOOt Cotton 1.6 0.49 90/10 Cotton/Wool 2.0 0.00 70/30 Cotton/Wool 1.6 0.49 84

Table 4.25

Interjudge Reliability of Fabric Hand Evaluation (Pearson Correlation Coefficients)

Judge 1 Judge 2 Judge 3 Judge 4 Judge 5

Judge 2 0.93 Judge 3 0.79 0.86 Judge 4 0.91 0.90 0.87 Judge 5 0.89 0.95 0.87 0.96 85

From the results reported in Table 4.25, it can be concluded that the judges were highly consistent in their ratings.

A one-way analysis of variance of subjective evaluation of fabric hand, for 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool fabrics is shown in Table 4.26. The results of the ANOVA disclosed that there was a highly significant interaction between control and enzyme treated fabrics.

When significant F ratios resulted from the ANOVA tests, the

Tukey's studentized range test was used to identify the existence of significant differences between groups. This post hoc comparison revealed differences between control and

3% treated fabric and control and 5% treated fabric.

However, no significant differences were found between 3% and 5% treated experimental fabrics. Therefore, Hypothesis

3 was rejected.

Summary of Data Analyses

Three hypotheses were formulated for the study. All hypotheses were tested using one-way analysis of variance to determine if significant relationships existed between untreated and treated fabrics of 100% cotton, 90/10 cotton/wool and 70/30 cotton/wool blended fabrics.

The first hypothesis, that there would be no significant differences in physical characteristics of experimental fabrics in breaking strength, abrasions resistance, dimensional stability, fabric stiffness, and 86

Table 4.26

One-Way ANOVA and Tukey's Studentized Range Test Results Subjective Evaluation of Fabric Hand

Source of Variance ss df MS F Sig. of F 100% Cotton Between Groups 38.53 2 19.27 96.30 0.0001* Within Groups 2.40 12 0.20 90/10 Cotton/Wool Between Groups 16.13 2 8.06 34.57 0.0001* Within Groups 2.80 12 0.23 70/30 Cotton/Wool Between Groups 17.73 2 8.87 53.20 0.0001* Within Groups 2.00 12 0.17

Treatment Level Control 3% Treatment 5% Treatment

Mean (100% Cotton) 5.00 1. 60 1. 60

Mean (90/10 Cotton/Wool) 4.20 2.00 2.00

Mean (70/30 Cot ton Wool) 4.20 1. 80 1. 60

* Indicates significance at 0.05 probability level. 87 wrinkle recovery, was rejected due to significant differences found between treated and untreated groups for each physical tests evaluated. The following exceptions were noted:

(1) In breaking strength, there was no significant differences between 3% and 5% treated experimental fabrics

in warp and filling directions.

(2) For abrasion resistance, there was no significant

difference between 3% and 5% treated fabrics in warp and

filling directions for 90/10 cotton/wool blended fabrics.

(3) For fabric stiffness, there was no significant

differences between 3% and 5% treated experimental fabrics

in warp and filling directions.

(4) In wrinkle recovery, there was no significant

difference between untreated and 3% treated fabric in warp

direction for 90/10 cotton/wool blend, also there was no

significant differences between 3% and 5% treated fabrics in

warp and filling directions for 100% cotton fabrics and

70/30 cotton/wool blended fabrics.

The second hypothesis, that there would be no

significant differences in surface appearance of treated and

untreated experimental fabrics with respect to pill

formation, was rejected due to significant differences. The

exception noted was, there was no significant differences

between 3% and 5% treated experimental fabrics. 88

The third hypothesis, that there would be no significant differences in subjective evaluation of untreated and treated fabrics with respect to fabric hand, was rejected due to significant differences. The exception noted was, there was no significant differences between 3% and 5% treated experimental fabrics. CHAPTER V

SUMMARY, FINDINGS, CONCLUSIONS

AND RECOMMENDATIONS

Short staple fibers have always posed problems in textile processing. The textile industry is striving continuously to develop new techniques to overcome the problems associated with the manufacture of fabrics made

from short staple fibers. Bio-finishing is one such

technical advancement where protruding short fibers are

removed permanently from the fabric surface by means of

enzymes. Some studies have been conducted to determine the effects of cellulase enzymes on cotton fabrics. However, a

review of reported literature revealed a void in research

addressing the effects of cellulase and protease enzymes on

cotton/wool blended fabrics. This study was conducted as an

exploratory effort in order to assess the effects of

cellulase and protease enzymes on cotton and cotton/wool blended fabrics. This chapter summarizes the study,

identifies major findings, and reports conclusions, based on analyses and interpretation of the results. In addition, recommendations for further research, based upon the

findings of the study, are made.

89 90

Summary of the Study

The purpose of this study was threefold: (1) to obtain and treat cotton and cotton/wool blended fabrics with cellulase and protease enzymes; (2) to examine the surface appearance of treated and untreated cotton and cotton/wool blended fabrics, and (3) to assess the differences in selected physical properties between treated and untreated cotton and cotton/wool blended fabrics. Experimental fabrics were developed at International Center for Textile

Research and Development, Texas Tech University, Lubbock,

Texas. The sample population was derived from 200 yards of experimental fabrics in each variety. Twenty yards in each variety were used for selected physical tests and subjective evaluation. Experimental fabrics were treated with enzymes.

Cellulase enzyme was applied on 100% cotton and on cotton/wool blended fabrics, to treat the cotton content of the blended fabric. Whereas protease enzyme was applied on cotton/wool blended fabrics to treat the wool content of the blended fabric. Enzymes were applied in two specific concentrations, 3% and 5% on weight by volume basis.

After samples were subjected to the standardized pretest conditions, they were tested by conducting selected physical tests, following ASTM and AATCC standards. subjective evaluation means also were used. The physical tests, which were conducted before and after enzyme treatments, included breaking strength, abrasion resistance, 91 dimensional stability, fabric stiffness, wrinkle recovery, and pilling resistance. Subjective evaluation was conducted by means of a panel to assess the fabric hand.

A variety of statistical procedures were used to analyze the results. Descriptive statistics was used to report means and standard deviations of selected physical tests. Hypotheses were tested using one-way analysis of variance and Tukey's studentized range test. Pearson r correlation coefficient was used to measure the interjudge reliability. The reliability coefficient alpha was calculated to assess the internal consistency of the scale used for subjective evaluation.

Discussion of Findings and Conclusions

Hypotheses l.a Statistically significant differences were observed between untreated and treated fabrics with regard to breaking strength. Enzyme treated fabrics exhibited about

12-18% strength loss. The decrease in breaking strength was caused by enzyme treatment, which removed the protruding loose fibers, thus reducing the strength of the fabrics.

These results can also be compared with the results obtained from fabric weight loss after enzyme treatments (refer

Appendix A). They seems to conform to the expected outcome. 92

Hypotheses 1.b

Statistically significant differences were observed

between untreated and treated fabrics with regard to

abrasion resistance. Enzyme treated fabrics showed about

20-55% loss in abrasion resistance. The reduction in

abrasion resistance was high for all experimental fabrics.

This phenomenon may be due to the mechanical action during

enzyme application as well as the removal of surface waxes,

fats and other naturally accompanying substances during

enzymatic treatment. However, as reported by Gagliardi

(1951, p.411)

abrasion resistance is only one property, and other mechanical properties may be more important to an end use. Only by considering composite chemical, physical, and mechanical properties of a fabric can one characterize its expected performance in use. Drawing conclusions from a single abrasion test, made in one particular manner, can lead to very erroneous understanding of the finished textile product.

Hypotheses 1.c

Statistically significant differences were observed between untreated and treated fabrics with regard to dimensional stability. Enzyme treated fabrics showed about

5-10% shrinkage. Cotton/wool blended fabrics showed less shrinkage compared to 100% cotton fabrics. A comparison of the degree of dimensional changes occurring after 1 and 5 laundering periods revealed that the major differences were found as a function of enzyme treatments. The reduction in shrinkage of cotton/wool blended fabrics is due to the 93 effect of enzyme treatment. The scales were softened as a result of enzyme treatment, hence shrinkage is prevented.

Hypotheses l.d

Statistically significant differences were observed between untreated and treated fabrics with regard to fabric stiffness. The enzyme treated fabrics were softer than untreated fabrics. One hundred percent cotton fabrics were more stiff compared to cotton/wool blended fabrics. This phenomenon is due to the specific properties of cotton and wool fibers. Molecules in cotton fibers are more crystalline hence are less extensible, whereas molecules in wool fibers are known for high elastic recovery and excellent compressional resiliency hence accounting for soft and flexible characteristics.

Hypotheses l.e Statistically significant differences were observed between untreated and treated fabrics with regard to wrinkle recovery. As a function of enzyme treatment the treated fabrics recovered from wrinkling more than untreated fabrics. Cotton/wool blended fabrics recovered more compared to 100% cotton fabrics. The increase in wrinkle recovery in blended fabrics can also be accounted for by the presence of wool fibers. It is a well-known fact that wool molecules form acute-angled helices, thus permitting a 94 greater extensibility, whereas cellulosic molecules have an extended chain-like structure, with little extensibility of its primary valence bonds (Morton & Hearle, 1975) .

Hypothesis 2

Statistically significant differences were observed between untreated and treated fabrics with regard to pilling resistance. Experimental fabrics treated with 3% and 5% enzymes received a 5.0 rating, indicating no pilling. This is due to efficient enzyme treatment confirming effective removal of protruding loose fibers. This result is further supported by scanning electron micrographs, which revealed considerable reduction in protruding loose fibers.

Hypothesis 3 Statistically significant differences were observed between untreated and treated fabrics with regard to fabric hand (softness) . A panel of 5 judges evaluated the fabric hand of untreated and treated fabric samples using a scale of 1.0 (very soft) to 5.0 (rough). The panel rated untreated samples between 4.0 and 5.0, whereas treated samples were rated between 1.0 and 2.0.

Recommendations for Further Research

Suggestions for further research related to results of this study follow: 95

1. Replicate the study with varying concentrations of enzymes.

2. Investigate the effects of enzyme treatment on the dyeability of cotton and wool fibers.

3. Study the effects of enzymes on the convolutions of cotton fibers and scales of wool fibers.

4. Conduct physical tests to assess the comfort properties in a detailed manner.

5. Explore further the effects of cellulase and protease enzymes by the use of high pressure liquid chromatography to determine the sugar and protein concentrations. REFERENCES

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Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297-334.

Gagliardi, D. D. (1951). The relation between fiber properties and apparent abrasion resistance. American Dyestuff Reporter. 40(6), 409-415.

Garrett, A. S. & Cedroni, D. M. (1992). Biopolishing of cellulosic textiles. AATCC Book of Papers. Atlanta. GA.

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Hamby, D. S. (Eds.). (1949). The American cotton hand book: vol.1. (3rd ed.). New York: Interscience Publishers.

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96 97 Joseph, M. L. (1986). Introductory textile science. (5th ed.). New York: Holt, Rinehart and Winston.

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Kochavi, D., Videbaek, T., & Cedroni, D. (1990, September). Optimizing processing conditions in enzymatic stonewashing. American dyestuff reporter. 79(9). pp. 24, 26, 28.

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Morton, W. E. & Hearle, J. W. S. (1975). Phvsical properties of textile fibers (2nd ed.). London: Heinemann.

Needles, H. L. (1986). Textile fibers, dyes, finishes, and processes. Park Ridge, NJ: Noyes Publications.

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Schubel, P. (1990, November). Cellulase. Textile industries dyegest-SA. ~(11). pp. 4-5, 14.

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Tortora, P. G. {1987). Understanding textiles. {4th ed.). New York: Macmillan Publishing Company.

Wolnak, B. {1978). Status of the U.S. enzyme industry in 1978. In Danehy, J. & Wolnak, B. {Eds.). Enzymes: The interface between technoloov and economics. New York: Marcel Dekker, Inc. APPENDIX

WEIGHT LOSS TEST RESULTS

99 100

Weight Loss Test Results

The weights of the experimental fabrics were measured before and after enzyme treatments and reported to the nearest grams. Table A.1 and Figure A.1 illustrate the percentage weight loss after enzyme treatment for all experimental fabrics at both level of treatments. As indicated by Table A.1 and Figure A.1, the percentage weight loss declined continuously at 3% and 5% treatment.

Cotton/wool blended fabrics lost more weight compared to

100% cotton fabrics. Fabrics treated with 5% enzymes lost more weight than 3% treated fabrics. The weight loss was due to the effective removal of surface microfibrils by enzymatic treatment, thus assuring proper bio-finishing effect. 101

Table A.1

Percentage Wight Loss After Enzyme Treatments

Percentage 3% Treatment 5% Treatment Fiber Content 100% Cotton 4.65 5.77

90/10 Cotton/Wool 5.76 6.16

70/30 Cotton/Wool 6.16 6.52 102

7 6 en en 5 j- --0.0 ·-~ ~ ~

5% Treatment c -0 - -0 3% Treatment 8 0 ~ ~ - 8 c:: 8 - -0 -0 ~c u 0 c -0 0- u 0\ 0 ('of'\ 0 r--

Figure A.l Percentage Weight Loss After Enzyme Treatments