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Fire-Safe Polymers and Polymer Composites University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations 1896 - February 2014 1-1-2003 Fire-safe polymers and polymer composites. Huiqing Zhang University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_1 Recommended Citation Zhang, Huiqing, "Fire-safe polymers and polymer composites." (2003). Doctoral Dissertations 1896 - February 2014. 1053. https://scholarworks.umass.edu/dissertations_1/1053 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations 1896 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. FIRE-SAFE POLYMERS AND POLYMER COMPOSITES A Dissertation Presented by HUIQING ZHANG Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 2003 Polymer Science and Engineering © Copyright by Huiqing Zhang 2003 All Rights Reserved FIRE-SAFE POLYMERS AND POLYMER COMPOSITES A Dissertation Presented by HUIQING ZHANG Approved as to style and content by: Phillfp R. Westmoreland, Co-Chair t ^aA • Thomas J. McCarthy, Department Head Polymer Science and Engineering ACKNOWLEDGMENTS Thank you, Dr. Farris and Dr. Westmoreland, for your guidance, advice and help throughout the past five years. Thank you for sharing your knowledge, experience and ideas. You are not only my advisors in research, but also in life. Dr. Coughlin, thank you for all the suggestions and discussions. Dr. Lyon, thank you for all your help and advice. I would also like to thank many people who gave me a lot of help in my research. Jennifer Stewart taught me how to operate all the instruments. Stanislav Stoliarov taught me how to use molecular modeling to study the thermal decomposition mechanism of polymers. Richard Walters helped me set up the pyrolysis-combustion flow calorimeter (PCFC) and helped me solve many problems thereafter. Robert Filipczak and Sean Crowley helped me carry out the OSU and cone calorimeter tests in the FAA. Jungsoo Kim, Terry Hobbs, Adam Zerda, Lei Zheng, Arthur Gavrin, Javid Rzayev, Alex Hsieh, Heidi Gibson, Christie Crowe, Rich Leibfried, and Prof. Zbigniew Brzozowski provided all kinds of samples for my research. Both my research groups have been a constant source of knowledge and support. I have not only learned a lot, but also had a lot of good time in these two groups. I thank all the people who had made the past five years such a fruitful and rewarding experience for me. Especially, my best friends, Yuqing Zhu and Zhiping Lai, they helped me get through many difficulties. I also gratefully acknowledge financial support from CUMIRP Cluster F funded by Boeing - Commercial Airplane Group, BP Amoco Polymers (now Solvay Advanced Polymers), the Federal Aviation Administration (FAA), Foster-Miller Inc., General iv Electric Co., NIST, Schneller Inc., Solutia Inc., and the US Army. Especially, FAA provided the facilities for OSU and cone calorimeter tests. BP Amoco Polymers and US Army provided many samples. Finally, I wish to express my deepest appreciation to my parents and my brother Zhicheng. They have been giving me the strongest support with their love and encouragement during my whole life. Also my special thanks to Matthias, a person who gives me a lot of support and happiness. v ABSTRACT FIRE-SAFE POLYMERS AND POLYMER COMPOSITES SEPTEMBER 2003 HUIQING ZHANG, B.S., TSINGHUA UNIVERSITY M.S., TSINGHUA UNIVERSITY Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Richard J. Farris and Professor Phillip R. Westmoreland The intrinsic relationships between polymer structure, composition and fire behavior have been explored to develop new fire-safe polymeric materials. Different experimental techniques, especially three milligram-scale methods - pyrolysis-combustion flow calorimetry (PCFC), simultaneous thermal analysis (STA) and pyrolysis GC/MS - have been combined to fully characterize the thermal decomposition and flammability of polymers and polymer composites. Thermal stability, mass loss rate, char yield and properties of decomposition volatiles were found to be the most important parameters in determining polymer flammability. Most polymers decompose by either an unzipping or a random chain scission mechanism with an endothermic decomposition of 100-900 J/g. Aromatic or heteroaromatic rings, conjugated double or triple bonds and heteroatoms such as halogens, N, O, S, P and Si are the basic structural units for fire-resistant polymers. The flammability of polymers can also be successfully estimated by combining pyrolysis GC/MS results or chemical structures with TGA results. vi The thermal decomposition and flammability of two groups of inherently fire- resistant polymers - poly(hydroxyamide) (PHA) and its derivatives, and bisphenol C (BPC II) polyarylates - have been systematically studied. PHA and most of its derivatives have extremely low heat release rates and very high char yields upon combustion. PHA and its halogen derivatives can completely cyclize into quasi- polybenzoxazole (PBO) structures at low temperatures. However, the methoxy and phosphate derivatives show a very different behavior during decomposition and combustion. Molecular modeling shows that the formation of an enol intermediate is the rate-determining step in the thermal cyclization of PHA. BPC II-polyarylate is another extremely flame-resistant polymer. It can be used as an efficient flame-retardant agent in copolymers and blends. From PCFC results, the total heat of combustion of these copolymers or blends changes linearly with composition, but the change of maximum heat release rates also depends on the chemical structure of the components. The flammability of various polymers and polymer composites measured by PCFC, cone calorimeter ASTM El 354 and Ohio State University (OSU) calorimeter ASTM E906 were also compared. For pure polymers, there is a relatively good correlation between different methods. However, for polymer composites with inert fillers or flame-retardant additives, OSU and cone calorimetries are more suitable evaluation methods. vii TABLE OF CONTENTS Page ACKNOWLEDGMENTS iv ABSTRACT vi LIST OF TABLES xiii LIST OF FIGURES xvi Chapter 1 . FIRE AND POLYMERS 1 1.1 Introduction 1 1 .2 Polymer combustion process 3 1 .3 Standard assessments and tests 5 1 .4 Flame-retardant chemistry 6 1 .5 Inhibition of polymer combustion 8 1.5.1 Intrinsically fire-resistant polymers 8 1.5.2 Flame-retardant additives 10 1.6 Thermal decomposition mechanisms of polymers 19 1 .7 Experimental techniques for thermal decomposition of polymers 20 1.8 References 23 2. QUANTITATIVE MEASUREMENTS ON THE THERMAL DECOMPOSITION AND FLAMMABILITY OF POLYMERS 28 2 . 1 Introduction 28 2.2 Methodology of flammability calculations 30 2.2.1 Calculation of the composition of the volatiles 32 2.2.2 Calculation of total heat of combustion and heat release capacity of polymer 33 2.3 Experimental 34 2.3.1 Pyrolysis-GC/MS 34 2.3.2 Simultaneous thermal analysis (STA) 35 2.3.3 Pyrolysis-combustion flow calorimeter (PCFC) 36 2.3.4 Materials 38 viii 31 2.4 Results and discussion 39 2.4.1 Thermal stability and decomposition process of polymers 39 2.4.2 Thermal decomposition products of polymers 49 2.4.3 Flammability 53 2.4.4 Bond dissociation energies of the polymers 55 2.4.5 Flammability calculated by pyrolysis GC/MS and STA results 60 2.4.6 Flammability estimated by using chemical structure and TGA results 62 2.5 Conclusions 70 2.6 References 72 3. LOW FLAMMABILITY AND THERMAL DECOMPOSITION OF POLY(HYDROXYAMIDE) (PHA) AND ITS DERIVATIVES 74 3.1 Introduction 74 3 .2 Experimental 76 3.2.1 Materials 76 3.2.2 Film preparation 77 3.2.3 Characterization 77 3.3 Results and discussion 79 3.3.1 Thermal stability and decomposition process of PHAs 79 3.3.2 Flammability 87 3.3.3 Characterization of chars by IR and elemental analysis 91 3.3.4 Identification of volatiles by GC/MS 95 3.3.5 Thermal decomposition mechanisms 101 3.4 Conclusions 107 3.5 References 109 4. FIRE-RESISTANT, UV/VISIBLE-SENSITIVE POLYARYLATES, COPOLYMERS AND BLENDS 11 4.1 Introduction 11 4.2 Experimental 113 4.2.1 Materials 113 4.2.2 Characterization 1 1 4.3 Results and Discussion 114 4.3.1 Flammability and thermal decomposition of BPA-polyarylates ....114 4.3.2 Thermal decomposition and flammability of homopolyarylates....! 14 4.3.3 UV/Visible-sensitive Chalcon II-polyarylate 119 4.3.4 Thermal decomposition and flammability of copolymers and terpolymers 122 4.3.5 Thermal decomposition and flammability of blends 126 4.4 Conclusions 130 4.5 References 131 5. EFFECTS OF FLAME-RETARDANT ADDITIVES AND CORRELATIONS AMONG PCFC, OSU AND CONE CALORIMETERS 133 5.1 Introduction 133 5.2 Experimental 1 36 5.2.1 Test samples 136 5.2.2 Sample preparation 136 5.2.3 Characterization 136 5.2.3.1 Ohio State University (OSU) calorimeter test 138 5.2.3.2 Cone calorimeter test 139 5.2.4 Terminology 1 39 5.3 Results and discussion 140 5.3.1 PMMA/clay nanocomposites 140 5.3.2 Poly(ether ether ketone)(PEEK) and composites 143 5.3.3 Xydar® and its composites 150 5.3.4 Polyphthamides (PPAs) and composites 157 5.3.5 Epoxy resins with phosphate flame retardants 171 5.3.6 Ignitability 176 5.3.7 Heat release rate 178 5.3.8 Correlation between different flammability tests 180 5.4 Conclusions 1 86 5.5 References 187 6. STRUCTURE-COMPOSITION-FLAMMABILITY RELATIONSHIPS OF POLYMERS 189 6.1 Introduction 189 6.2 Experimental 1 90 \ 6.2.1 Materials 190 6.2.2 Characterization 1 90 6.2.3 Terminology 1 90 6.3 Chemical structure 190 6.3 . 1 Main chain - polysulfones 1 90 6.3.1.1 Thermal decomposition processes 191 6.3.1.2 Decomposition volatiles 198 6.3.1.3 Flammability measured by PCFC 200 6.3.
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