Preface In the early 1990s, a research team from Toyota Central Research Development Laboratories in Japan worked on Nylon 6 clay nanocomposites and revealed an improved process for producing Nylon 6 clay nanocomposites using in situ polymerisation similar to the Unichika Co. (Japan) method, who produced the first organoclay hybrid polyamide nanocomposite. The first commercialisation of polymer nanocomposites took place in 1991 with the development of timing belt covers by Toyota Motor Co. In 2002, General Motors initiated a step-assist automotive component made of polyolefin reinforced with 3% nanoclay and, over the last decade, nanocomposite production has increased. The objective of this book is to discuss the increasing demand for light weight automotive rubber parts and the role of polymer composites. Due to their advantages, e.g., superior strength and light weight, the application of polymer nanocomposites in automotive components enables the production of light weight vehicles, improved engine efficiency and decreased carbon dioxide emissions, which results in enhanced automobile performance. It is forecasted that by the year 2022, the production of light vehicles on a global scale will reach 112 million units. In parallel, the global polymer nanocomposite market will be worth US $12,000 million by 2022. Stringent government directives governing automotive emissions in a number of countries including, the USA, Germany, China, India and so on, have led to the growing use of polymer nanocomposites. A team of ingenious scientists, professors and experienced rubber professionals, with extensive knowledge and research experience involving polymer nanocomposites and nanotextiles in automobile applications, have all contributed to this book. The many advantages of nanocomposites over conventional composites, in terms of mechanical, electrical, thermal, barrier and chemical properties, e.g., increased tensile strength, improved heat deflection temperature, flame retardancy and so on, are reviewed in this book. In addition, examples of the scope and applications in the automobile industry, e.g., hoses, seals, tyres, tubes and flaps, are highlighted. iii
Rubber Nanocomposites and Nanotextiles in Automobiles This book is comprised of six chapters that detail comprehensive views on the polymer nanocomposites and nanotextiles that feature in the fast-growing lighter automotive industry. Chapter 1 portrays the scope of application of elastomeric nanocomposites in automotive engineering with the utilisation of organoclay masterbatches that are light weight and exhibit balanced mechanical properties. Chapter 2 focuses on manufacturing tyre treads, with a description of elastomer nanocomposites, a vital component of pneumatic tyres that provide an extraordinary balance among three operational requirements, i.e., safety, comfort and cost. Chapter 3 is a narrative on automotive components with respect to their mechanical characteristics. Chapter 4 discusses rubber clay nanocomposites in relation to automobile components, and how the nanofillers, contrary to conventional ones, can significantly improve the functional properties of polymers. Rubber nanocomposites have also received considerable interest for strategic and critical applications in defence and aerospace sectors, which are also highlighted in this chapter. Chapter 5 details a comprehensive discussion regarding the advantages of ionic liquid(s) (IL)- mediated surface modification of multi-walled carbon nanotubes (CNT) over other methods, and the different roles of IL in CNT rubber composites. An overview of CNT elastomer composites is also presented. Nanofibres (NF) or nanocomposite fibres for functional nanofinishing, nanocoatings or polymer nanocomposite coatings are gaining considerable interest for the development of smart, functional and high-performance textiles. Nanocomposite fibres have immense potential in automobile engineering components, and may transform the textile industry with new functionalities including: self-cleaning surfaces, conducting textiles, antimicrobial properties, controlled hydrophilicity and hydrophobicity, protection against fire and ultraviolet radiation, which are reviewed in Chapter 6. The focus of this book is to offer concise information to the automobile component manufacturing industry, polymer technologists, students and researchers to obtain an overall view of polymer nanocomposites, its development and various applications in automobiles; in combination with the elaborate idea of NF and textiles engineered in the automobile industry. It is perceivable that future automobiles, railways and aerospace will endeavour to extensively employ nanotechnology. I would like to express my sincere appreciation and gratitude to Ms Helene Chavaroche, Commissioning Editor, for her most sincere efforts to make this project successful and also to Mrs Eleanor Garmson, the Development Editor. We also appreciate the editorial service provided by Dr Liz Rees. I indeed express my earnest thanks to all the staff of Smithers Rapra who assisted in the preparation and publication of this book. iv
Contents Preface... iii Contributors... xiii 1 Applications of Rubber Nanocomposites in Automotives... 1 1.1 Introduction... 1 1.2 Rubber in Automobiles... 2 1.2.1 Tyres, Tubes and Flaps... 3 1.2.2 Automotive Belts... 4 1.2.3 Automotive Hose... 4 1.2.3.1 Brake Hose...4 1.2.3.2 Fuel Hose...4 1.2.3.3 Fuel Injection Hose...4 1.2.3.4 Heater Hose...5 1.2.3.5 Liquefied Petroleum Gas Vapour Hose...5 1.2.3.6 Power Steering Hose...5 1.2.3.7 Automotive Seals...6 1.2.3.8 Automotive Tubing...6 1.2.3.9 Door Seal and Window Channels...6 1.2.3.10 Diaphragms and Rubber Boots...6 1.2.3.11 Other Miscellaneous Rubber Parts...7 1.3 Prime Requirements of Different Elastomeric Auto Components from an Application Point-of-View... 7 1.4 Elastomeric Nanocomposites and the Rubber Industry... 7 1.5 Superiority of Clays/Clay Minerals versus Other Nanofillers... 11 1.6 Organo-modified Clay/Clay Minerals... 11 v
Rubber Nanocomposites and Nanotextiles in Automobiles 1.7 Application of Elastomeric Nanocomposites in the Automotive Industry... 11 1.7.1 Lighter Weight and Balanced Mechanical Properties... 12 1.7.2 Barrier or Air Retention Properties... 15 1.7.3 Ageing and Ozone Resistance... 17 1.7.4 Solvent Resistance... 18 1.7.5 Better Processability... 19 1.7.6 Elastomeric Polyurethane Organoclay Nanocomposites... 22 1.7.7 Use of Organoclay Nanocomposites in Tyres... 23 1.8 Disadvantages of Using Organoclay Elastomeric Nanocomposites in the Automotive Industry... 26 1.9 Conclusion... 27 2 Rubber Nanocomposites for Tyre Tread Applications... 37 2.1 Introduction... 37 2.1.1 Introduction to Tyres... 37 2.1.2 Brief History of Fillers in Tyre Tread Applications... 39 2.2 Morphology and Dispersion of Fillers in Natural Rubber, Styrene-Butadiene Rubber and their Blend Nanocomposites... 45 2.2.1 Morphology and Dispersion of Fillers in Natural Rubber Nanocomposites... 45 2.2.2 Morphology and Dispersion of Fillers in Styrene-Butadiene Rubber Nanocomposites... 49 2.2.3 Morphology and Dispersion of Fillers in NR/SBR, SBR/rNBR and PS/NBR Blend Nanocomposites... 52 2.3 Mechanical Properties of Natural Rubber, Styrene-Butadiene Rubber and their Blend Nanocomposites... 53 2.3.1 Mechanical Properties of Natural Rubber Nanocomposites... 53 2.3.2 Mechanical Properties of Styrene-Butadiene Rubber Nanocomposites... 57 2.3.3 Mechanical Properties of Natural Rubber and Styrene- Butadiene Rubber Blend Nanocomposites... 64 2.4 Dynamic Mechanical Thermal Analysis of Natural Rubber, Styrene-Butadiene Rubber and its Blends... 68 2.4.1 Dynamic Mechanical Thermal Analysis and Natural Rubber Nanocomposites... 68 vi
Contents 2.4.2 Dynamic Mechanical Thermal Analysis of Styrene- Butadiene Rubber Nanocomposites... 69 2.5 Thermogravimetric Analysis of Natural Rubber, Styrene- Butadiene Rubber and its Blend Nanocomposites... 71 2.5.1 Thermogravimetric Analysis/Differential Thermal Analysis of Natural Rubber Nanocomposites... 71 2.5.2 Thermogravimetric Analysis/Differential Thermal Analysis of Styrene-Butadiene Rubber Nanocomposites... 73 2.6 Differential Scanning Calorimetry of Natural Rubber, Styrene-Butadiene Rubber and its Blend Nanocomposites... 74 2.6.1 Natural Rubber Nanocomposites... 74 2.6.2 Styrene-Butadiene Rubber Nanocomposites... 75 2.7 Abrasion Resistance of Natural Rubber, Styrene-Butadiene Rubber and its Blend Nanocomposites... 75 2.8 Heat Build-up of Natural Rubber, Styrene-Butadiene Rubber and its Blend Nanocomposites... 77 2.9 Conclusions... 78 3 Nanofilled Thermoplastic Vulcanisates in Automotive Applications... 89 3.1 Basic concepts of Thermoplastic Elastomers and Thermoplastic Vulcanisates... 89 3.1.1 Thermoplastic Elastomers... 89 3.1.2 Thermoplastic Vulcanisates... 92 3.1.3 Concept of Dynamic Vulcanisation and Morphology Development of Thermoplastic Vulcanisates... 93 3.1.4 Preparation of Thermoplastic Vulcanisates... 94 3.2 Various Types of Thermoplastic Vulcanisates... 96 3.2.1 Polypropylene Ethylene Propylene Diene Rubber-based Thermoplastic Vulcanisates... 96 3.2.1.1 Phenolic Resin-cured Thermoplastic Vulcanisates...97 3.2.1.2 Sulfur-cured Thermoplastic Vulcanisates...97 3.2.1.3 Peroxide-cured Thermoplastic Vulcanisates...98 3.2.1.4 Thermoplastic Vulcanisates based on Electron-induced Reactive Processing...103 3.2.2 Polypropylene Ethylene Octane Copolymer-based Thermoplastic Vulcanisates... 104 vii
Rubber Nanocomposites and Nanotextiles in Automobiles 3.2.3 Miscellaneous Thermoplastic Vulcanisates... 108 3.2.4 End-use Applications of Thermoplastic Vulcanisates... 110 3.3 Concept of Nanocomposites... 111 3.3.1 Composites... 111 3.3.2 Polymeric Composites... 111 3.3.3 Polymer Nanocomposites... 112 3.3.4 Various Types of Nanofillers for the Development of Polymer Nanocomposites... 112 3.3.4.1 Nano-silica...113 3.3.4.2 Carbon Nanotubes...113 3.3.4.3 Layered Silicates...113 3.3.4.4 Montmorillonite...115 3.3.5 Advantages of Nanocomposites... 117 3.3.6 Requirements of Thermoplastic Vulcanisate Nanocomposites... 118 3.3.7 Preparation of Thermoplastic Vulcanisate Nanocomposites via the Melt-mixing Technique... 118 3.4 Various Nanofilled Thermoplastic Vulcanisates... 119 3.4.1 Organoclay-filled Thermoplastic Vulcanisate Nanocomposites... 120 3.4.1.1 Thermoplastic Vulcanisate Nanocomposites based on Commercially Available Thermoplastic Vulcanisates...120 3.4.1.2 Thermoplastic Vulcanisate Nanocomposites based on Polypropylene Ethylene Propylene Diene Rubber Thermoplastic Vulcanisates...121 3.4.1.3 Polypropylene Ethylene Propylene Diene Rubber Thermoplastic Vulcanisate Nanocomposites Produced by Electron-induced Reactive Processing...122 3.4.1.4 Styrene Acrylonitrile Ethylene-Vinyl Acetatebased Thermoplastic Vulcanisate Nanocomposites...124 3.4.2 Nano-silica-filled Thermoplastic Vulcanisates... 126 3.4.3 Graphite-based Thermoplastic Vulcanisate Nanocomposites... 129 3.5 Applications of Thermoplastic Vulcanisate Nanocomposites... 130 3.6 Summary and Conclusion... 130 viii
Contents 4 Elastomer Clay Nanocomposites with Reference to their Automobile Applications and Shape-Memory Properties... 135 4.1 Introduction... 135 4.1.1 Shape-memory Effect in Polymers... 137 4.1.2 Programming of Shape-Memory Polymers... 138 4.1.3 Figure of Merit... 140 4.1.3.1 Shape Fixity...140 4.1.3.2 Shape Recovery...140 4.1.3.3 Recovery Speed...141 4.1.4 Molecular Mechanism of the Shape-Memory Effect in Polymers... 141 4.1.4.1 Chain Conformation...141 4.1.4.2 Entropic Elasticity...141 4.1.4.3 Molecular Mechanism of Shape-Memory Polymers...142 4.2 Role of Rubber Clay Nanocomposites in Automobile Applications... 142 4.3 Polyurethane Clay (Attapulgite) Nanocomposites for Shape-memory Applications... 151 4.3.1 Current Scenario and Literature Gap... 151 4.3.2 Attapulgite Segmented Polyurethane Nanocomposites... 152 4.3.3 Shape Recovery under Unconstrained Conditions... 160 4.3.4 Recovery Speed/Response Time under Unconstrained Conditions... 160 4.3.5 Shape Recovery under Constrained Conditions... 162 4.3.6 Recovery Speed/Response Time under Constrained Conditions... 163 4.4 Summary and Conclusions... 164 5 The Role of Ionic Liquids in Carbon Nanotube Rubber Composites... 175 5.1 An Overview of Carbon Nanotube Elastomer Composites... 175 5.2 Carbon Nanotubes A Brief History... 177 5.3 Ionic Liquids... 180 5.3.1 Origin of Ionic Liquids... 180 5.3.2 Structure of Ionic Liquids... 181 5.3.2.1 Effect of Cations...182 ix
Rubber Nanocomposites and Nanotextiles in Automobiles 5.3.2.2 Effect of Anions...182 5.3.3 Properties of Ionic Liquids... 182 5.3.4 Applications of Ionic Liquids... 183 5.3.5 Main Limitations of Ionic Liquids... 185 5.3.6 Future of Ionic Liquids... 185 5.4 Carbon Nanotube Ionic Liquid Polymer Composites... 185 5.4.1 Mechanism behind the Exfoliation of Nanofillers by Ionic Liquids... 186 5.4.2 Advantages of Ionic Liquid-mediated Surface Modification of Multi-walled Carbon Nanotubes over Other Methods... 188 5.4.3 Novel Materials based on Ionic Liquid-modified Carbon Nanotubes... 189 5.4.4 Fabrication of Ionic Liquid-modified Carbon Nanotube Polymer Nanocomposites... 189 5.4.4.1 Solution Processing of Carbon Nanotubes and Polymers...189 5.4.4.2 Melt Mixing...190 5.4.4.3 Bulk Mixing...190 5.4.4.4 In Situ Polymerisation...190 5.4.4.5 Other Methods...191 5.4.5 Different Roles of Ionic Liquids in Carbon Nanotubes/Rubber Composites... 191 5.4.5.1 Coupling Agents between Rubber and Carbon Nanotubes...191 5.4.5.2 Dispersant for Carbon Nanotubes in a Rubber Matrix...192 5.4.5.3 Cure Accelerator...195 5.4.5.4 Plasticiser...196 5.5 Conclusion... 196 6 Nanotechnology-based Textiles: A Solution for the Emerging Automotive Sector... 207 6.1 Introduction... 207 6.2 Textiles used in Automobiles... 208 6.2.1 Automotive Textiles: Market Scenario... 208 6.2.2 Textile Fibres used in Automobiles... 210 x
Contents 6.2.3 Textile Structures used in Automobiles... 211 6.2.4 Interior Automotive Textiles... 211 6.2.5 Textiles for Tyre Cord Applications... 216 6.2.6 Textiles for Automotive Filter Applications... 217 6.2.7 Textiles in Automotive Battery Separators... 217 6.2.8 Textiles in Automotive Fuel Cells... 218 6.2.9 Textile-reinforced Composites for Automotive Structural Components... 219 6.2.10 Other Miscellaneous Applications of Textiles in Automobiles... 220 6.3 Nanotechnologies for Automotive Textiles... 220 6.3.1 Applications and Market Potential... 220 6.3.2 Nanofinishing and Nanocoatings to produce Functional Automotive Fabrics... 222 6.3.2.1 What is Nanofinishing?...222 6.3.2.2 What is Nanocoating?...222 6.3.2.3 Water- and Oil-repellent Nanofinishes and Nanocoatings for Automotive Textiles...224 6.3.2.4 Self-cleaning Automotive Fabrics...225 6.3.2.4.1 Photocatalytic Self-cleaning Nanofinishing or Nanocoating...228 6.3.2.5 Antimicrobial and Antiodour Nanofinished/ Nanocoated Automotive Fabrics...230 6.3.2.6 Fragrance-finished Automotive Fabrics...233 6.3.2.7 Ultraviolet-protective Nanofinished/Nanocoated Automotive Fabrics...234 6.3.2.8 Antistatic-nanofinished Automotive Fabrics...235 6.3.2.9 Flame-retardant Nanofinished/Nanocoated Fabrics...235 6.3.3 Polymer Nanocomposites in Automobiles... 236 6.3.3.1 Polymer Nanocomposites in Automotive Body Parts...237 6.3.3.2 Polymer Nanocomposites for Tyre Applications...239 6.3.3.2.1 Polymer Nanocomposite-based fibres for Tyre Cord Application...239 6.3.3.2.2 Rubber Nanocomposites for Tyre Applications...239 xi
Rubber Nanocomposites and Nanotextiles in Automobiles 6.3.3.2.3 Polymer Nanocomposite-based Interlayer Coatings...240 6.3.3.3 Polymer Nanocomposite-coated and Laminated Automotive Textiles...241 6.3.3.3.1 Polymer Clay Nanocomposite Coatings...241 6.3.3.3.2 Polymer Silica Nanocomposite Coatings...242 6.3.3.3.3 Polymer Carbon Nanotube Nanocomposite Coatings...242 6.3.3.3.4 Other Polymer Nanocompiste Coatings...243 6.3.4 Nanofibres in Automotive Applications... 243 6.3.4.1 Electrospun Nanofibre-based Automotive Filters...244 6.3.4.2 Application of Electrospun Nanofibres in Automotive Energy Devices...245 6.3.4.2.1 Electrospun Nanofibres for Rechargeable Lithium-ion Batteries...245 6.3.4.2.2 Electrospun Nanofibres for Supercapacitors...246 6.3.4.2.3 Electrospun Nanofibres for a Hydrogen Generator and Storage Device of Hydrogen Cars...247 6.3.4.2.4 Electrospun Nanofibres for an Automotive Fuel Cell...248 6.3.4.3 Nano-enabled Automotive Textiles for Noise Control...249 6.3.5 Nanosensors in Automotive Textiles... 249 6.3.6 NanoBreeze TM Car Air Purifier... 251 6.4 Current Difficulties/Challenges for Nano-enhanced Automotive Textiles... 252 6.5 Future Scope of Nanotechnology-enhanced Automotive Textiles... 253 6.6 Summary/Conclusion... 254 References... 255 Abbreviations... 267 Index... 277 xii