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Effects of Fiberimatiux Interactions on the Interfacial Deformation Micromechanics of Cellulose-Fiberipolymer Composites William Tai-Yin Tze

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Effects of Fiberimatiux Interactions on the Interfacial Deformation Micromechanics of Cellulose-Fiberipolymer Composites William Tai-Yin Tze The University of Maine DigitalCommons@UMaine Electronic Theses and Dissertations Fogler Library 8-2003 Effects of Fiberimatiux Interactions on the Interfacial Deformation Micromechanics of Cellulose-Fiberipolymer Composites William tai-Yin Tze Follow this and additional works at: http://digitalcommons.library.umaine.edu/etd Part of the Organic Chemistry Commons, and the Wood Science and Pulp, Paper Technology Commons Recommended Citation Tze, William tai-Yin, "Effects of Fiberimatiux Interactions on the Interfacial Deformation Micromechanics of Cellulose-Fiberipolymer Composites" (2003). Electronic Theses and Dissertations. 422. http://digitalcommons.library.umaine.edu/etd/422 This Open-Access Dissertation is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of DigitalCommons@UMaine. EFFECTS OF FIBERIMATIUX INTERACTIONS ON THE INTERFACIAL DEFORMATION MICROMECHANICS OF CELLULOSE-FIBERIPOLYMER COMPOSITES BY William Tai-Yin Tze B. For. Sc. Agricultural University of Malaysia (UPM), 1992 M.S. Michigan Technological University, 1998 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Forest Resources) The Graduate School The University of Maine August, 2003 Advisory Committee: Douglas Gardner, Professor of Wood Science and Technology, Co-Advisor Carl Tripp, Professor of Chemistry, Co-Advisor Stephen Shaler, Professor of Wood Science and Technology William Unertl, Professor of Physics Timothy Rials, Professor of Wood Science, University of Tennessee LIBRARY RIGHTS STATEMENT In presenting this thesis in partial fulfillment of the requirements for an advanced degree at The University of Maine, I agree that the Library shall make it fieely available for inspection. I hrther agree that permission for "fair use" copying of this thesis for scholarly purposes may be granted by the Librarian. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission. Signature: Date: EFFECTS OF FIBERIMATRIX INTERACTIONS ON THE INTERFACIAL DEFORMATION MICROMECHANICS OF CELLULOSE-FIBERIPOLYMER COMPOSITES By William Tai-Yin Tze Thesis Co-Advisors: Dr. Douglas Gardner and Dr. Carl Tripp An Abstract of the Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Forest Resources) August, 2003 The overall objective of this dissertation was to gain an understanding of the relationship between interfacial chemistry and the micromechanics of the cellulose- fiberlpolymer composites. Regenerated cellulose (lyocell) fibers were treated with amine-, phenylamine-, phenyl-, and octadecyl-silanes, and also styrene-maleic anhydride copolymer. Inverse gas chromatography was conducted to evaluate the modified surfaces and to examine the adsorption behavior of ethylbenzene, a model compound for polystyrene, onto the fibers. Micro-composites were formed by depositing micro-droplets of polystyrene onto single fibers. The fiber was subjected to a tensile strain, and Raman spectroscopy was employed to determine the point-to-point variation of the strain- and stress-sensitive 895 cm-' band of cellulose along the embedded region. Inverse gas chromatography studies reveal that the I,-, values, calculated by matching the Lewis acid parameter (K,) and basic parameter (K,) between polystyrene and different fibers, were closely correlated to the acid-base adsorption enthalpies of ethylbenzene onto the corresponding fibers. Hence, I was subsequently used as a convenient indicator for fiberlmatrix acid-base interaction. The Raman micro-spectroscopic studies demonstrate that the interfacial tensile strain and stress are highest at the edge of the droplet, and these values decline from the edge region to the middle region of the embedment. The maximum of these local strains corresponds to a strain-control fracture of the matrix polymer. The minimum of the local tensile stress corresponds to the extent of fiber-to-matrix load transfer. The slope of the tensile stress profile allows for an estimation of the maximum interfacial shear stress, which is indicative of fiberlpolymer (practical) adhesion. As such, a novel micro-Raman tensile technique was established for evaluating the ductile-fiberlbrittle- polymer system in this study. The micro-Raman tensile technique provided maximum interfacial shear stress values of 8.0 to 13.8 MPa, ranking functional groups according to their practical adhesion to polystyrene: alkyk untreated < phenyl = phenylamine = styrene copolymer < arnine. Overall, interfacial bonding can be increased by increasing the acid-base interactions (Ia-,) or reducing the chemical incompatibility (A6) between the fibers and matrix. Therefore, interfacial chemistry can be employed to enhance and predict cellulose-fiberlpolymer adhesion to better engineer composite properties and ultimately better utilize bio-resources. ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my co-advisors, Dr. Douglas Gardner and Dr. Carl Tripp, for their invaluable advice of this dissertation. Dr. Gardner has provided me with unfailing support without which, I could not have completed my Ph.D. program. Dr. Carl Tripp has spent countless hours with me in making the Raman spectroscopic studies a success. Also acknowledged are other members of my dissertation committee: Dr. Stephen Shaler, Dr. William Unertl, and Dr. Timothy Rials for their constructive suggestions in my research work. I owe a debt of gratitude to Research Associate Shane 0' Neil1 who built the micro-Raman tensile stage and the data acquisition system that allowed me to proceed with my proposed research. Dr. Magnus Whlinder, now of the Swedish Institute for Wood Technology Research (Tratek), was a resourceful colleague and mentor during his fellowship as the post-doctorate researcher in Dr. Gardner's group. Dr. Sofian Kanan, now of the American University of Sharjah, U.A.E., was practically my problem solver in the early stage of my research with Dr. Tripp. I also derived numerous benefits fi-om interacting with chemists of Dr. Tripp's research group: Dr. Anil Waghe (now with the University of Oklahoma), Mr. Zhixiang Lu (now a Ph.D. student in the University of Massachusetts), Ms. Haiyan Li, Ms. Cuihong Jiang, and Mr. Wei Gu, whose support and assistance are greatly appreciated. It has been a good experience working in two of the dynamic and scientific- excel groups of Maine: the Advanced Engineered Wood Composites Center (AEWC) and the Laboratory for Surface Science and Technology (LASST). I thank the administrative and technical staff of both the centers. Of notable mention is the kind personal attention provided by Ms. Doreen Parent and Ms. Marcy Smith. Also deserving to be mentioned is my official affiliation at Maine: the Department of Forest Management. I thank Dr. David Field, the head of the department, for opening up a wonderful learning experience by accepting me to the Ph.D. program. I am grateful to Ms. Cindy Paschal and Ms. Dolores Stone, for taking care of my administrative-related business. Other people who have improved the quality of my educational experience are (1) Dr. Joseph Genco, my advisor for the Pulp and Paper Certificate Program during my initial year at Maine, (2) Ms. Jane Morse of the Writing Center, and (3) Ms. Kylie Gallant, my speech tutor who worked with the Conley Speech and Hearing Center. Also provided equal, if not more, significant contributions are staff from the Office of International Program especially Mr. James Leck and Ms. Mireille Le Gal. During my five years of stay at Maine, I have acquainted many nice people. Among them, I would like to mention Dr. Lech Muzynski and Ms. Danuta Muzynska who generously shared with me many important celebrations and precious moments of their time. Other people who have been supportive and providing invaluable friendship were Dr. Jungil Son, Dr. Cihat Tasciglu (now in Turkey), and Mr. Leopold Eisenheld (now in Austria). All in all, I have been fortunate to be surrounded by many wonderfbl people, and it is not easy to mention each by name here. For these people, I pray for their happiness, and that I can reciprocate their kindness in the future. I am indebted to Acordis Cellulosic Fibers for donating the lyocell fibers used in this study. I acknowledge the financial support from the USDFJCSREES New England Wood Utilization Research Fund, which funded my Ph.D. study. Also, I appreciate the approval of the Forest Products Society to use two figures from its publications in this dissertation (Figures 4.3 and 4.4). Last but not least, I would like to thank my parents, who provided me with a decent childhood and fundamental education, laying the foundation of my value and personal development. I am also thankful to my brothers who have been looking out for me, and who believed that I could make it for the Ph.D. degree. TABLE OF CONTENTS .. ACKNOWLEDGEMENTS ................................................................................................11 LIST OF TABLES ............................................................................................................. ix LIST OF FIGURES ...........................................................................................................xi Chapter 1. INTRODUCTION ...........................................................................................................1 1.1. Potentials and Advantages
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