E n g in Engineering Plastics Published by Smithers Rapra Technology Ltd, 2014 e e r i n g P l a s t i c s Generally speaking, engineering plastics are those which are replacing conventional materials such as metals and alloys in general engineering. In addition, the term ‘engineering plastic’ covers materials that have superior properties which were not particularly available in conventional polymeric materials such as the exceptionally high heat resistance of polyimides and polysulfides. In addition to conventional materials engineering polymers include materials as diverse as polyether ether ketone, polyimide, polyetherimide and polysulfides and polysulfides. Engineering polymers can be reinforced by the inclusion in their formulations of glass fibres, carbon fibres and nanotubes which produce appreciable improvements in mechanical and thermal properties. The book aims to provide a complete coverage of the types of plastics which are now T.R. Crompton increasingly being used in engineering in applications as diverse as gears, aircraft body construction, micro-electronics and extreme high temperature applications, steel replacement and artificial hip joints. The book also intends to provide a complete review of the use of polymers in engineering. The mechanical, electrical and thermal properties of polymers are discussed as are other diverse applications such as solvent and detergent resistance, frictional and hardness properties, food packaging applications and gas barrier properties. In addition a very important application is discussed of the resistance of plastics to gamma and other forms of radiation namely their use in nuclear industry, medical applications and food sterilisation. The book will be of interest to those at all levels who are concerned with general engineering, building, automotive, aerospace, electronics, mechanical and nuclear industries. It will also be of interest as a source book to materials scientists, those concerned with the development of new materials and students of engineering and related studies. T . R . C r o Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK m Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118 p t Web: www.polymer-books.com o n Top left front cover image: Lockheed Martin’s F-35 Lightning II benefits from a range of high-temperature thermoset composites in its construction. ©Lockheed Martin Corporation Engineering Plastics T.R. Crompton A Smithers Group Company Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118 http://www.polymer-books.com First Published in 2014 by Smithers Rapra Technology Ltd Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK ©Smithers Information Ltd., 2014 All rights reserved. Except as permitted under current legislation no part of this publication may be photocopied, reproduced or distributed in any form or by any means or stored in a database or retrieval system, without the prior permission from the copyright holder. A catalogue record for this book is available from the British Library. Every effort has been made to contact copyright holders of any material reproduced within the text and the author and publishers apologise if any have been overlooked. ISBN: 978-1-84735-568-3 (hardback) 978-1-84735-569-0 (softback) 978-1-84735-570-6 (ebook) Typeset by Argil Services P reface This book aims to provide a complete review of the use of polymers in engineering but first it is necessary to discuss what is meant by an engineering plastic. Generally speaking, engineering plastics are those, which are replacing conventional materials such as metals and alloys in general engineering. In addition, the term engineering plastic covers materials that have superior properties, which were not particularly available in conventional polymeric materials such as the exceptionally high heat resistance of polyimides and polysulfides. Engineering polymers can be reinforced by including in their formulations, glass fibres, carbon fibres and nanotubes, which produce appreciable improvements in mechanical and thermal properties. In addition to conventional materials engineering polymers include materials as diverse as polyether ether ketone, polyimide, polyetherimide and polysulfides. The book aims to provide a complete coverage of the types of plastics, which are now increasingly being used in engineering in applications as diverse as gears, aircraft body construction, micro-electronics and extreme high temperature applications, steel replacement and artificial hip joints. Chapters 1-4 of the book deal with the mechanical, electrical and thermal properties of a wide range of unreinforced and reinforced engineering plastics. Chapter 5 discusses various miscellaneous properties such as wear, abrasion resistance, frictional hardness properties, surface properties and weathering, and chemical resistance. In addition, this chapter covers a particular property of food packaging plastics, namely their gas barrier properties. Chapter 5 concludes with a discussion of the prediction of the service lifetime to be expected of engineering plastics. Chapters 6-8 discuss the application of plastics in various types of industry including automotive, aerospace, mechanical and general engineering. iii Engineering Plastics Plastics are now being used as a replacement in applications as diverse as gears, aircraft body’s constructions, micro-electronics, extreme high-temperature applications and hip joints. The mechanical, electrical and thermal properties of polymers will be discussed. Other diverse applications such as solvent and detergent resistance, frictional hardness properties, food packaging applications and gas barrier properties are also discussed. In addition a very important application is discussed, the resistance of plastics to gamma and other forms of radiation in the nuclear industry, medical applications and food sterilisation. The book will be of interest to those at all levels who are concerned with general engineering, and the building, automotive, aerospace, electronics, mechanical and nuclear industries. It will also be of interest as a source book to materials scientists, to those concerned with the development of new materials and students of engineering and related studies. iv C ontents 1 Introduction ...............................................................................................1 1.1 Mechanical Applications .................................................................2 1.2 Electrical Applications ....................................................................3 1.3 Thermal Applications .....................................................................3 1.4 Miscellaneous Applications .............................................................3 1.5 Significant Polymer Properties .........................................................3 2 Mechanical Properties of Polymers .............................................................7 2.1 Review of Mechanical Properties ....................................................7 2.2 Mechanical Properties of Unreinforced Polymers ..........................14 2.2.1 Polyolefins .......................................................................14 2.2.2 Polyphenylene Oxide .......................................................16 2.2.3 Epoxy Resin .....................................................................16 2.2.4 Acrylic Resins ..................................................................16 2.2.5 Polyether Ether Ketone ....................................................17 2.2.6 Polyethylene Terephthalate ..............................................17 2.2.7 Polyimides .......................................................................18 2.2.8 Fluorinated Polyimides ....................................................18 2.2.9 Polyamide-imide ..............................................................19 2.2.10 Polyamides .......................................................................19 2.2.11 Polyurethanes ..................................................................23 2.2.12 Polyphenyl Sulfone ..........................................................24 2.3 Reinforced Plastics ........................................................................24 2.3.1 Glass Fibre Reinforcement ...............................................24 v Engineering Plastics 2.3.2 Applications of Carbon Fibre Reinforcement ...................24 2.3.3 Other Reinforcing Agents ................................................24 2.4 Comparison of the Mechanical Properties of Virgin and Reinforced Plastics ........................................................................28 2.4.1 Tensile Strength ................................................................28 2.4.2 Flexural Modulus ............................................................29 2.4.3 Elongation at Break .........................................................30 2.4.4 Izod Impact Strength ........................................................31 2.4.5 Relaxation Behaviour of Polymers ...................................32 2.5 Mechanical Properties of Particular Polymers ...............................32 2.5.1 Polyether Ether Ketone ....................................................32 2.5.2 Epoxy Resins ...................................................................32 2.5.3 Polyethylene Terephthalate ..............................................34 2.5.4 Polydiallylphthalate .........................................................34 2.5.5 Polyamides .......................................................................35 2.5.6 Polystyrene ......................................................................38 2.5.7 Polypropylene ..................................................................38 2.5.8 Polyethylene .....................................................................39 2.5.9 Ethylene-vinyl Acetate .....................................................40 2.5.10 Ethylene Propylene Diene – Polypropylene – Maleic Anhydride Vulcanisates ....................................................40 2.5.11 Polymethyl Methacrylate .................................................40 2.5.12 Fluoropolymers ................................................................40 2.5.12.1 Polyvinylidene Fluoride-clay Nanocomposites ...40 2.5.12.2 Poly(vinylidene fluoride)-Tetrafluroethylene- Propylene ...........................................................41 2.5.13 Natural Rubber and Isoprene Rubber ..............................41 2.6 Use of Lubricating Agents in Engineering Polymer Formulations ..41 3 Thermal Properties of Polymers ...............................................................53 3.1 Introduction ..................................................................................53 vi Contents 3.2 Thermal Expansion Coefficient .....................................................57 3.3 Mould Shrinkage ..........................................................................58 3.4 Melting Temperature or Softening Point .......................................59 3.4.1 Polyaryl Ether Ketone ......................................................60 3.4.2 Polyester Amide ...............................................................61 3.4.3 Polyimides and Polyamides ..............................................61 3.5 Maximum Operating Temperature ...............................................61 3.6 Brittleness Temperature (Low Temperature Embrittlement Temperature) ................................................................................62 3.7 Heat Distortion Temperature ........................................................63 3.7.1 Heat Distortion Temperature at 0.45 MPa (˚C) ................63 3.7.2 Heat Distortion Temperature at 1.80 MPa (˚C) ................63 3.8 Thermal Conductivity ...................................................................64 3.9 Specific Heat .................................................................................66 3.9.1 Hot Wire Techniques .......................................................66 3.9.2 Transient Plane Source Technique ....................................66 3.10 Thermal Diffusivity .......................................................................67 3.11 Thermal Insulation Index ..............................................................67 3.12 Glass Transition Temperatures ......................................................67 3.13 Alpha, Beta and Gamma Transitions .............................................70 3.13.1 Dynamic Mechanical Analysis .........................................71 3.13.2 Differential Thermal Analysis ..........................................73 3.13.3 Infrared Spectroscopy ......................................................73 3.13.4 Dielectric Thermal Analysis .............................................73 3.14 Developments in High Temperature Plastics .................................74 3.14.1 Introduction .....................................................................74 3.14.2 Polyimides .......................................................................80 3.14.3 Fluorinated Polyimides ....................................................80 3.14.4 Polyamide-imide ..............................................................80 3.14.5 Polyether-imide ................................................................80 vii Engineering Plastics 3.14.6 Polyphenylene Sulfide ......................................................81 3.14.7 Polyxylenyl Sulfide ...........................................................82 3.14.8 Polyether Sulfone and Polyphenylene Sulfide ...................82 3.14.9 Organosilicon Polymers ...................................................84 4 Electrical Properties of Polymers ..............................................................91 4.1 Introduction ..................................................................................91 4.1.1 Dielectric Constant ..........................................................93 4.1.2 Dielectric Strength ...........................................................93 4.1.3 Volume Resistivity ...........................................................97 4.1.4 Dissipation Factor ............................................................97 4.1.5 Electrical Resistance and Resistivity .................................97 4.1.6 Surface Arc Resistance .....................................................97 4.1.7 Tracking Resistance .........................................................98 4.2 Typical Electrical Properties of a Range of Engineering Polymers .99 4.3 Effect of Reinforcing Agents on Electrical Properties ....................99 4.4 Applications of High Dielectric Strength Polymers ......................100 4.5 Effect of Reinforcing Agents on Electrical and Mechanical Properties ....................................................................................104 4.5.1 Glass Fibre Reinforcement .............................................104 4.5.2 Silica Resin Reinforcement .............................................104 4.5.3 Carbon Fibre Reinforced Plastics ...................................105 4.5.4 Carbon Nanotubes ........................................................105 4.5.5 Carbon Black and Carbon Fibre ....................................106 4.6 Electrical Properties ....................................................................107 4.6.1 Dielectric Strength .........................................................107 4.6.2 Volume Resistivity .........................................................107 4.6.3 Dielectric Constant ........................................................108 4.6.4 Tracking Resistance .......................................................109 4.6.5 Failure of Electrical Properties .......................................110 viii Contents 4.6.6 Electrical Conductivity ...................................................110 4.6.7 Electrical Resistance .......................................................110 4.7 Electrically Conducting Polymers ................................................111 4.7.1 Polyaniline .....................................................................111 4.7.2 Carbon Nanotubes ........................................................114 4.7.3 Metal containing Electrically Conductive Polymers........114 4.7.4 Other Conducting Polymers ...........................................115 4.8 Fire Retardant Plastics for the Electrical Industry........................115 5 Miscellaneous Polymer Properties ..........................................................125 5.1 Abrasion Resistance and Wear ....................................................125 5.2 Fatigue Index ..............................................................................130 5.3 Coefficient of Friction .................................................................131 5.4 Surface Hardness ........................................................................132 5.5 Haze, Glass and Surface Roughness ............................................133 5.6 Weathering Properties of Engineering Plastics .............................135 5.7 Chemical Resistance....................................................................137 5.8 Detergent Resistance ...................................................................137 5.9 Solvent Resistance .......................................................................138 5.10 Hydrolytic Stability and Water Absorption .................................140 5.11 Gas Barrier Properties of Plastics ................................................141 5.12 Prediction of Polymer Service Lifetimes.......................................144 6 Plastics in Automotive Engineering ........................................................159 6.1 Applications ................................................................................159 6.1.1 Polypropylene and Polyethylene .....................................161 6.1.2 Ethylene-propylene-diene ...............................................162 6.1.3 Polyether Ether Ketone ..................................................163 6.1.4 Polyesters .......................................................................163 6.1.5 Polyethylene Terephthalate ............................................163 6.1.6 Polyamides .....................................................................164 ix