Introduction to Polymer Science and Technology
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Mustafa Akay Introduction to Polymer Science and Technology 2 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology © 2015 Mustafa Akay & bookboon.com ISBN 978-87-403-0087-1. 3 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Contents Contents Preface 8 Acknowledgements 9 1 Introduction 10 1.1 History of the development of polymers 10 1.2 Why a clear understanding of material is important? 12 1.3 What can be achieved by appropriate selection of polymer-based materials? 17 1.4 What makes polymers versatile? 20 2 Polymerisation 31 2.1 Polymerisation mechanisms 31 2.2 Polymerisation processes 36 2.3 Polymerisation reactors 39 2.4 Catalysts 42 2.5 Molecular weight and molecular weight distributions 47 2.6 Self-assessment questions 50 4 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Contents 3 Polymer processing 54 3.1 Concept of rheology 54 3.2 Processing and forming thermoplastics 56 3.3 Processing and forming thermosetting polymers 98 3.4 Self-assessment questions 109 4 Microstructure 111 4.1 Stereoregularity 112 4.2 Morphology in semi-crystalline thermoplastics 113 4.3 Degree of crystallinity 116 4.4 Crosslinking 124 4.5 Copolymer arrangements 126 4.6 Domain structures 127 4.7 Degree of molecular orientation 128 4.8 Self-assessment questions 130 5 Behaviour of polymers 133 5.1 Degradation of Polymers 133 5.2 Viscoelasticity 134 5.3 Relaxation transitions 150 5.4 Self-assessment questions 158 5 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Contents 6 Mechanical properties 163 6.1 Introduction 163 6.2 Tensile properties 166 6.3 Flexural properties 179 6.4 Compressive properties 184 6.5 Shear properties 186 6.6 Hardness 187 6.7 Impact properties and fracture toughness 189 6.8 Bearing strength 196 6.9 Environmental stress cracking 199 6.10 Fatigue and wear 202 6.11 Self-assessment questions 206 7 Thermal properties 209 7.1 Differential scanning calorimetry 210 7.2 Thermogravimetric analysis 218 7.3 Thermomechanical analysis 221 7.4 Dynamic mechanical thermal analysis 225 7.5 Determination of softening temperature 248 7.6 Self-assessment questions 257 References 261 6 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology To my parents (Rahmetullahi Aleyhima), to my wife, and to Mevlüde, Latifa and Melek, the apples of my eye 7 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Preface Preface Learning involves acquiring knowledge, which is encouraged in all traditions. For example, the Quran urges people to seek knowledge and to use it for the well being of society: “My Lord, increase me in knowledge”, Al-Quran 20:114. Knowledge should be applied in a safe, responsible and ethical manner not only to benefit us personally but also to improve the lot of the people we live with. It is also a duty to ensure that our surrounding habitat is not endangered. This sometimes requires knowledge of the local culture to help achieve a desirable outcome. Martin Palmer’s presentation on BBC Thought for the Day programme, 17/06/2006, on the subject of the protection of the oceans included: “To many around the world the environmental movement and its proffered solutions - usually economic - are alien ways of thinking and seeing the world, and can be interpreted as telling people what is best for them whether they like it or not. Let me tell you a story. Dynamite-fishing off the East African coast is a major problem. Environmental organisations have been addressing it for years, from working with Governments, to sending armed boats to threaten those illegally fishing. None of this worked because it had no relationship to the actual lives or values of the local fishermen all of whom are Muslims. What has worked off one island, Misali, is the Qur’an. In the Qur’an, waste of natural resources is denounced as a sin. Once local imams had discovered this, they set about preaching that dynamite fishing was anti-Islamic, non- sustainable and sinful. This ended the dynamite fishing of the Misali fishermen because it made sense to them spiritually.” The subject of this book is covered in seven chapters. The chapters are arranged in an attempt to reflect the three pillars of materials science and technology: in materials, there is a strong link between processing, microstructure and properties. Changing one affects the others and this has enabled scientists/engineers to tailor materials to suit purposes. Nature provides many examples of how materials comply with the processing-microstructure-properties relationship, e.g., one of the wonders of the world, the Giant’s Causeway consists of regular columns of polygonal slabs of volcanic basalt deposition juxtaposed the same material in rubble form with no recognisable shape. Based on the prevailing conditions, particularly that of temperature and the rate of cooling, the lava has solidified in regular as well as irregular forms. The processing- properties link is also highlighted by Leo Baekeland, the inventor of the first commercial plastic: “I was trying to make something really hard, but then I thought I should make something really soft instead, that could be molded into different shapes. That was how I came up with the first plastic. I called it Bakelite.” Chapter 1 in this book is introductory and includes a history of the development of polymers; the importance of the knowledge of materials for engineers and technologists; what makes polymeric materials attractive over conventional materials and a description of the versatile nature of polymers. The subsequent two chapters deal with the polymerisation processes and the processes employed in the conversion of polymeric raw materials into products. Chapter 4 covers the microstructural features in polymers, including lamellae, spherulites, crosslinking, and the measurements of degrees of crystallinity and molecular orientation. The viscoelastic nature of polymers, the time/temperature sensitivity of viscoelasticity and how this manifests itself in the form of creep, stress relaxation and mechanical damping are covered in Chapter 5. Glass transition and its dependence on molecular features are also covered in Chapter 5. The last two chapters cover various aspects of mechanical and thermal properties of polymers. Writing this book has been educational, and I thank BookBoon for giving me the opportunity. Mustafa Akay, N. Ireland, February 2015 8 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Acknowledgements Acknowledgements The book emerges from my work at the Ulster Polytechnic/University of Ulster, where I met and worked with various characters and personalities and I would like to mention Lesley Hawe, the late Archie Holmes and Myrtle Young who epitomise for me the constant kindness, help and support I received from the academic, technical and secretarial staff over the years. The book incorporates material taken from various sources, including my lecture notes, research outcomes of my postgraduate students, some of them have become friends for life, and some excellent text books, research papers/news, industry/company/organisation literature and web material that we are so fortunate to have access to. The sources of the materials used are gratefully acknowledged and are listed as references, however, over the years material permeates into teaching notes that is not always possible to trace the references for. I apologise, therefore, for any such material that has no accompanying reference and I express my thanks and gratitude to the people concerned. A special thank you goes to my wife for the offers of regular walks to blow away the cobwebs and visits to “Mugwumps” for coffee. 9 Download free eBooks at bookboon.com Introduction to Polymer Science and Technology Introductions 1 Introduction 1.1 History of the development of polymers “Genius is one percent inspiration and ninety-nine percent perspiration.” Thomas A. Edison, 1847-1931. Edison, one of the most prolific inventors in history, has appreciated the work of others, believed in team working, and has stated, “I start where the last man left off.” Over time, the work of the pioneers of polymer science, some listed below, has been gratefully acknowledged by others and developed upon. 1839 Eduard Simon discovered polystyrene. 1843 Hancock in England and Goodyear in USA developed the vulcanisation of rubber by mixing it with sulphur. Charles Goodyear epitomizes the 99% perspiration attitude: toiled all his life in spite of many set-backs and disappointments. 1854 Samuel Peck produced “union cases” for photographs by mixing shellac (produced from the secretions of the lac beetle which live on trees native to India and South-East Asia) sawdust, other chemicals and dye, and heated and pressed the mixture into a mould to form the parts of a Union Case. The term “union” refers to the material composition, i.e., synonymous with the terms mixture or blend. 1862 Alexander Parkes exhibited Parkesine, made from cellulose nitrate, at an International Exhibition in London. 1868 The Hyatt brothers in America produced celluloid from cellulose nitrate mixed with camphor. This was unstable and subsequently led to the development of cellulose acetate. They developed many of the first plastics mass production techniques such as blow moulding, compression moulding and extrusion. 1869 Daniel Spill took over the rights to manufacture Parkesine in England and established the Xylonite Company producing Xylonite and Ivoride. 1872 Eugen Baumann, one of the first to invent polyvinyl chloride (PVC). 1897 Spitteler in Germany patented casein, marketed as Galalith, made from protein from milk mixed with formaldehyde. 1907 Leo Baekeland produced phenol-formaldehyde, the first truly synthetic plastic, Bakelite. Cast with pigments to resemble onyx, jade, marble and amber it has come to be known as phenolic resin.