Mechanical Properties of Solid Polymers

John Sweeney, PhD, holds a Personal Chair in Polymer Mechanics at the University of Bradford. He is an expert in solid polymer behavior, including viscoelasticity, fracture mechanics, shear banding, large deformations, and nanocomposites. Peter Hine, PhD, is Associate Professor in the School of Physics and Astronomy at the University of Leeds, UK. His research is focused on understanding how the structure of polymers and polymer composites affect their mechanical properties.

• Preface xiii1 Structure of Polymers 11.1 Chemical Composition 11.2 Physical Structure 9References 17Further Reading 182 The Mechanical Properties of Polymers: General Considerations 192.1 Objectives 192.2 The Different Types of Mechanical Behaviour 192.3 The Elastic Solid and the Behaviour of Polymers 212.4 Stress and Strain 222.5 The Generalized Hooke’s Law 26References 293 Finite Strain Elasticity 313.1 The Generalized Definition of Strain 313.2 The Stress Tensor 433.3 The Stress–Strain Relationships 443.4 The Use of a Strain-Energy Function 48References 62Further Reading 634 Rubber-Like Elasticity 654.1 General Features of Rubber-Like Behaviour 654.2 The Thermodynamics of Deformation 664.3 The Statistical Theory 694.4 Modifications of Simple Molecular Theory 764.5 The Internal Energy Contribution to Rubber Elasticity 854.6 Applications Using Finite Element Modelling 874.7 Conclusions 88References 88Further Reading 915 Linear Viscoelastic Behaviour 935.1 Viscoelasticity as a Phenomenon 935.2 Mathematical Representation of Linear Viscoelasticity 985.3 Dynamical Mechanical Measurements: The Complex Modulus and Complex Compliance 1095.4 The Relationships Between the Complex Moduli and the Stress Relaxation Modulus 1145.5 The Relaxation Strength 120References 122Further Reading 1226 The Measurement of Viscoelastic Behaviour 1256.1 Creep and Stress Relaxation 1256.2 Dynamic Mechanical Thermal Analysis (DMTA) 1286.3 Wave-Propagation Methods 128References 1327 Experimental Studies of Linear Viscoelastic Behaviour as a Function of Frequency and Temperature: Time–Temperature Equivalence 1357.1 General Introduction 1357.2 Time–Temperature Equivalence and Superposition 1417.3 Transition-State Theories 1437.4 The Time–Temperature Equivalence of the Glass Transition Viscoelastic Behaviour in Amorphous Polymers and the Williams, Landel and Ferry (WLF) Equation 1477.5 Normal-Mode Theories Based on Motion of Isolated Flexible Chains 1567.6 The Dynamics of Highly Entangled Polymers 160References 1638 Anisotropic Mechanical Behaviour 1678.1 The Description of Anisotropic Mechanical Behaviour 1678.2 Mechanical Anisotropy in Polymers 1688.3 Measurement of Elastic Constants 1718.4 Development of Mechanical Anisotropy in Oriented Polymers 1818.5 Interpretation of Mechanical Anisotropy: General Considerations 1888.6 Experimental Studies of Anisotropic Mechanical Behaviour and Their Interpretation 1938.7 The Aggregate Model for Chain-Extended Polyethylene and Liquid Crystalline Polymers 2088.8 Auxetic Materials: Negative Poisson’s Ratio 212References 2159 Morphology and Structural Effects 2239.1 Evolution of Structures Under Tension: Cavitation 2239.2 Effects of Stress Field 2259.3 One-Dimensional Modelling 2299.4 Three-Dimensional Models 235References 24110 Relaxation Transitions: Experimental Behaviour and Molecular Interpretation 24510.1 Amorphous Polymers: An Introduction 24510.2 Factors Affecting the Glass Transition in Amorphous and Low Crystallinity Polymers 24710.3 Relaxation Transitions in Crystalline Polymers 25210.4 Conclusions 265References 26511 Non-linear Viscoelastic Behaviour 26911.1 The Engineering Approach 27011.2 The Rheological Approach 273References 294Further Reading 29712 Yielding and Instability in Polymers 29912.1 Discussion of the Load–Elongation Curves in Tensile Testing 30012.2 Ideal Plastic Behaviour 30712.3 Historical Development of Understanding of the Yield Process 31712.4 Experimental Evidence for Yield Criteria in Polymers 32012.5 The Molecular Interpretations of Yield 32512.6 Yield Considered to Relate to the Movement of Dislocations or Disclinations 33812.7 The Billon Model 34612.8 Multi-axial Deformation: Three-Dimensional Plasticity 34712.9 Cold-Drawing, Strain Hardening and the True Stress–Strain Curve 35012.10 Shear Bands 35812.11 Physical Considerations Behind Viscoplastic Modelling 360References 363Further Reading 37113 Fracture 37313.1 Definition of Tough and Brittle Behaviour in Polymers 37313.2 Principles of Brittle Fracture of Polymers 37413.3 Finite Geometries 37913.4 Elastic Anisotropy 38113.5 Controlled Fracture in Brittle Polymers 38213.6 Crazing in Glassy Polymers 38413.7 Controlled Fracture in Tough Polymers 39313.8 Factors Influencing Brittle–Ductile Behaviour: Brittle–Ductile Transitions 40313.9 The Impact Strength of Polymers 41013.10 The Tensile Strength and Tearing of Polymers in the Rubbery State 41713.11 Time and Temperature Effects 42013.12 Fatigue in Polymers 424References 429Further Reading 438Index 439