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Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion

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Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion By K.M. Zamil Andalib A thesis submitted in conformity with the requirements For the degree of Master of Applied Science Department of Mechanical and Industrial Engineering University of Toronto © Copyright by K.M. Zamil Andalib 2015 Increasing Void Fraction of the Polypropylene Foams Blown with Chemical Blowing Agents in High Temperature Extrusion K.M. Zamil Andalib Master of Applied Science Department of Mechanical and Industrial Engineering University of Toronto 2015 ABSTRACT The global demand for the polymeric foams especially Polypropylene (PP) foams is increasing rapidly. Some industrial processing of the PP foam need high processing temperature. But, there are only a few research has been done on high temperature processing as the quality of foam deteriorates in that condition. Moreover, Physical Blowing Agents (PBA) need additional accessories to process the foam. But usually industries are reluctant to change their existing system to get foamed output initially. This thesis develops an approach to manufacture PP foams with Chemical Blowing Agents (CBA) in high temperature extrusion. In the first step, a series of fundamental studies have been carried out by investigating the effect of different chemical blowing agent and content, pressure drop rate and residence time on the foaming behavior of polypropylene. And then, optimized parameters are applied and the combination effect of CBA-PBA and the effect of nucleating agents has been examined. II To my beloved wife, Prova For all the sacrifices, love and support during my journey to MASc degree. III ACKNOWLEDGMENT Words are not good enough for the acknowledgment to those people who helped me through my academic life in University of Toronto. Without their generosity and encouragement my journey toward M.A.Sc. Degree would never be successful. First of all I would like to thank Prof. Chul B. Park from the bottom of my heart for his valued supervision, personal guidance and encouragement throughout my research in the Microcellular Plastics Manufacturing Laboratory. I have learned so much from him throughout these two years which is integral for my growth as a mechanical engineer, and will be a solid foundation for my future career. I would like to thank my M.A.Sc. Oral Exam committee, Professor Kamran Behdinan and Professor Lidan You, for their valuable feedback in my M.A.Sc. oral examination. My gratitude is also extended to the Department of Mechanical and Industrial Engineering and the School of Graduate Studies at the University of Toronto. I would also like to thank AUTO21 for providing me with funding and opportunities to expand my research and professional networks. I would also like to take this opportunity to acknowledge the support from my previous and current colleagues of MPML. Their friendships are integral parts of my graduate studies experience. My research works would not have been as successful without their advice and assistance, especially Dr. Raymond Chu. I also want thank Kara Kim for her kind assistance. My special thanks goes out to Dr. Changwei Zhu, Dr. Saleh Amani, Dr. Amir Ameli, Dr. Davoud Jahani, Dr. Nemat Hossieny, Dr. Ali Rizvi, Dr. Adel Ramezani Kakroodi, Dr. Minh-Phuong Tran, Dr. Pengjian Gong, IV Dr. Guilong Wang, Dr. Long Wang, Lun Howe Mark, Weidan Ding, Sasan Rezaei, Palaniappan Arumugam, Hasan Mahmood, Mohammed Alshrah, Seongsoo Bae, Yasamin Kazemi, Alireza Tabatabaei, Mehdi Saniei, Vahid Shaayegan, Piyapong Buahom, Junghyub Lee, Chongxiang Zhao, Pavani Cherukupally, Sai Wang as well as everyone else who helped me during my M.A.Sc. studies. I also want give a special thanks to Ryan Mendell, Jeff Sansome and Tai Tran Do: thank you for the professional machining services and the numerous advice you have given me for the development of my foaming systems. Also, to the administrative staff in our department: Brenda Fung, Jho Nazal and Ed Baluyut: thank you for your help and advice on various administrative issues that allow me to focus on my research work. I also want to thank Cesar Sanches for all the help regarding the purchase of the different parts of my foaming system. Finally, I owe a big thanks to my awesome wife Prova, my wonderful parents from Bangladesh and my brother Ayon for their never-ending unconditional support, encouragement and patience throughout the years. Their caring support carried me through the difficult times and always inspired me to go forward in this long journey. And last but not least, my gratitude to the Almighty for providing me with the kind opportunity to pursue the degree. V TABLE OF CONTENTS ABSTRACT ............................................................................................................................................... II ACKNOWLEDGMENT .......................................................................................................................... IV TABLE OF CONTENTS ......................................................................................................................... VI LIST OF FIGURES.................................................................................................................................. IX NOMENCLATURE ................................................................................................................................. XI CHAPTER 1 INTRODUCTION ............................................................................................................... 1 1.1 PREAMBLE .................................................................................................................................. 1 1.2 OVERVIEW OF THE POLYMERIC FOAMS ............................................................................ 1 1.3 RESEARCH MOTIVATION ........................................................................................................ 3 1.4 OBJECTIVE OF THE THESIS .................................................................................................... 4 1.5 OVERVIEW OF THE THESIS .................................................................................................... 5 CHAPTER 2 LITERATURE REVIEW AND THEORETICAL BACKGROUND ............................. 7 2.1 INTRODUCTION ......................................................................................................................... 7 2.2 POLYMERIC MICROCELLULAR FOAMING ......................................................................... 7 2.2.1 Formation of single phase solution of Polymer and Gas ...................................................... 8 2.2.1.1 Solubility......................................................................................................................................... 9 2.2.1.2 Diffusivity ..................................................................................................................................... 12 2.2.1.3 Plasticization Effect of Gas ........................................................................................................... 13 2.2.2 Cell Nucleation .................................................................................................................... 14 2.2.2.1 Classical Bubble Nucleation ......................................................................................................... 15 2.2.2.2 Pseudo-Classical Bubble Nucleation ............................................................................................ 16 2.2.2.3 Stress Induced Nucleation............................................................................................................. 17 2.2.3 Cell Growth ......................................................................................................................... 18 2.3 BLOWING AGENT .................................................................................................................... 19 2.3.1 Physical blowing agent (PBA) ............................................................................................. 20 2.3.2 Chemical blowing agent (CBA) ........................................................................................... 22 2.4 FOAMING PROCESSES ........................................................................................................... 24 2.4.1 Batch Foaming Process ....................................................................................................... 24 2.4.2 Continuous Foaming Process .............................................................................................. 26 2.5 FACTORS AFFECTING FOAM EXTRUSION ........................................................................ 29 2.5.1 Crystallization Kinetics ....................................................................................................... 29 VI 2.5.2 Filamentary Die Design in Foam Extrusion ....................................................................... 31 2.5.3 Governing Mechanism of Volume Expansion ..................................................................... 32 2.5.4 Residence Time of the Polymer in the Extrusion System ..................................................... 36 2.6 CHARACTERIZATION OF THE FOAM SAMPLES .............................................................. 37 2.6.1 Foam Density ...................................................................................................................... 37 2.6.2 Volume Expansion Ratio & Void Fraction .........................................................................
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