NANOCOMPOSITES BASED ON NANOCELLULOSE WHISKERS A Dissertation Presented to The Academic Faculty by Amit Saxena In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Chemistry and Biochemistry Georgia Institute of Technology May, 2013 NANOCOMPOSITES BASED ON NANOCELLULOSE WHISKERS Approved by: Dr. Arthur J. Ragauskas, Advisor Dr. Lawrence A. Bottomley School of Chemistry and Biochemistry School of Chemistry and Biochemistry Georgia Institute of Technology Georgia Institute of Technology Dr. Yulin Deng Dr. Preet Singh School of Chemical and Biomolecular School of Materials Science and Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. John Zhang School of Chemistry and Biochemistry Georgia Institute of Technology Date Approved: January 3rd , 2013 DEDICATION This dissertation is dedicated to my lovely wife Shilpi with love and admiration and my parents for their love, support, care and encouragement throughout the course of my doctoral research. ACKNOWLEDGEMENTS I wish to thank Dr. Art Ragauskas for his support, advice and mentorship during my doctoral studies. I would also like to thank my thesis committee, Dr. Yulin Deng, Dr. Preet Singh, Dr. John Zhang and Dr. Lawrence Bottomley, for their insightful comments and support from the initial to the final level of this project. I am grateful to my co-workers at Georgia Tech, especially Dr. Marcus Foston, Dr. Mohamad Kassaee, for their support in many aspects during the completion of this project. I am grateful to all the friends I made along the way, for making my stay in Atlanta so memorable. Finally, thanks to my wife and my parents for their undying support and all my strength from their unconditional love. I derived inspiration from their sacrifice, encouragement from their faith, found happiness in their pride. I also would like to acknowledge the financial support from the Paper Science and Engineering Fellowship program at the Institute of Paper Science and Technology. IV TABLE OF CONTENTS ACKNOWLEDGEMENTS ....................................................................... IV LIST OF TABLES ..................................................................................... IX LIST OF FIGURES ................................................................................... XI CHAPTER 1: INTRODUCTION ............................................................... 1 CHAPTER 2: LITERATURE REVIEW ..................................................... 7 2.1 Cellulose ......................................................................................................... 7 2.2.1 Crystalline structure of cellulose .................................................................. 11 2.2.2 Amorphous cellulose………………………………………………………...14 2.3 Cellulose whiskers .......................................................................................... 18 2.4 Cellulose whiskers preparation ....................................................................... 22 2.5 Hemicellulose ................................................................................................. 31 2.6 Polymer nanocomposite .................................................................................. 35 2.6.1 Cellulose whiskers nanocomposite .......................................................... 36 2.7 Model studies ........................................................................................................ 39 2.8 Biodegradable films ............................................................................................... 44 2.9 Migration process .................................................................................................. 52 2.10 Tortuosity ............................................................................................................ 53 2.11 Tortuosity calculation .......................................................................................... 53 2.12 Summary ............................................................................................................. 55 v CHAPTER 3 MATERIALS AND METHODOLOGIES ......................... 56 3.1 Materials .............................................................................................................. 56 3.2 Processing ........................................................................................................... 57 3.2.1 Solution processing of xylan-sulfonated nanocellulose nanocomposite film....... 57 3.2.2 Solution processing of xylan-hydrochloride nanocellulose nanocomposite film. 57 3.2.3 Solution processing of xylan- kraft softwood fiber and acacia reinforced film ... 58 3.3 Preparation of sulfonated cellulose whiskers ...................................................... 58 3.4 Conductometric titration method: charge determination ...................................... 59 3.5 Preparation of hydrochloride nanocrystalline cellulose ......................................... 59 3.6 Characterization techniques ................................................................................. 60 3.6.1 Mechanical properties ........................................................................... 60 3.6.2 Water vapor transmission rate (WVTR) ............................................... 61 3.6.3 Oxygen permeability analysis ................................................................ 61 3.6.4 Mercury intrusion porosimetry analysis ................................................. 62 3.6.5 Conductometric titration ........................................................................ 62 3.6.6 Atomic force microscopy (AFM) analysis ............................................. 62 3.6.7 Optical microscopy analysis .................................................................. 62 3.6.8 Scanning electron microscopy (SEM) ................................................... 62 3.6.9 Transmission electron microscopy (TEM) ............................................. 62 3.6.10 Nuclear Magnetic Resonance (NMR) Analysis .................................... 63 3.6.11 X-ray diffraction (XRD) ...................................................................... 63 3.6.12 Fourier transform infrared spectroscopy (FT-IR) ................................. 63 vi CHAPTER 4 XYLAN-NANOCELLULOSE COMPOSITES ................... 64 4.1 Introduction ........................................................................................................... 64 4.2 Results and discussion ........................................................................................... 65 4.2.1 Mechanical properties ............................................................................. 66 4.2.2 Morphology of the composite films ......................................................... 70 4.3 Summary ............................................................................................................... 73 CHAPTER 5 WATER TRANSMISSION BARRIER PROPERTIES OF BIODEGRADABLE FILMS BASED ON CELLULOSIC WHISKERS AND XYLAN............................................................................................ 75 5.1 Introduction ........................................................................................................... 75 5.2 Results and discussion .......................................................................................... 76 5.2.1 Water vapor transmission rate properties ................................................. 77 5.2.2 Morphology of xylan-cellulose whiskers and xylan-soft wood fibers composite ................................................................................................ 79 5.3 Summary ............................................................................................................... 82 CHAPTER 6 MOISTURE BARRIER PROPERTIES OF XYLAN COMPOSITE FILMS ................................................................................ 84 6.1 Introduction ........................................................................................................... 84 6.2 Results and discussion ........................................................................................... 86 6.2.1 Moisture barrier properties of xylan composite films ............................. 87 6.2.2 Spectroscopy .......................................................................................... 91 6.2.3 Morphology of xylan composite films .................................................... 93 6.3 Summary ............................................................................................................. 97 vii CHAPTER 7 OXYGEN BARRIER PROPERTIES OF XYLAN COMPOSITE FILMS ............................................................................... 99 7.1 Introduction ........................................................................................................... 99 7.2 Results and discussion ......................................................................................... 101 7.2.1 Oxygen transmission rate studies of nanocomposite films ..................... 101 7.2.2 Morphology of cross section and surface images of composite films ..... 105 7.3 Summary ............................................................................................................. 108 CHAPTER 8 FUNDAMENTAL STUDIES ON XYLAN- CELLULOSE WHISKERS COMPOSITE FILMS ......................................................... 110 8.1 Introduction ........................................................................................................