Crazing

Abstract: (The Nature of Polymer Glasses, Their Packing Density and Mechanical Behaviour).- The Nature of Polymeric Glasses.- The common glassy polymers.- The softening of polymer glasses.- Polymer melts and rubbers.- The crystallisation of polymers.- Amorphous isotactic polymers.- The morphology of amorphous polymers.- Packing Volume in the Glassy State.- The expansion volume of amorphous polymers.- Free volume concepts derived from viscosity theories.- Viscosity and free volume in polymers.- Geometrical factors affecting the possible value of the free volume at Tg.- Bernal's random close packed volume.- The Rigidity of Polymer Glasses.- Large Deformations and Fracture.- References.- 1 The Thermodynamics of the Glassy State.- 1.1 Introductory Thermodynamic Considerations.- 1.2 Glassy Solidification and Transition Phenomena.- 1.2.1 General considerations and transitions of different order.- 1.2.2 Glassy solidification with one or several internal parameters.- 1.2.3 Experimental results.- 1.2.4 Position of the equilibrium curve below the glass temperature.- 1.2.5 Zero point volume of a polymer.- 1.3 Results of the Thermodynamic Theory of Linear Relaxation Phenomena.- 1.4 Glassy Mixed Phases.- 1.4.1 The glassy solidification of polymer solutions.- 1.4.2 The glassy solidification of cross-linked systems. The coexistence of glassy phases with phases in internal equilibrium.- 1.5 The Mobility and Structure of Glassy Phases.- References.- 2 X-Ray Diffraction Studies of the Structure of Amorphous Polymers.- 2.1 Introduction.- 2.2 The Interaction of X-rays With Matter.- 2.2.1 Scattering by a free electron.- 2.2.2 Interference among scattered waves.- 2.2.3 Atomic scattering factor.- 2.2.4 Compton scattering.- 2.3 Order and Orientation in Polymers.- 2.3.1 Order.- 2.3.2 Orientation.- 2.4 Diffraction of X-rays by Amorphous Materials.- 2.5 Small Angle X-ray Scattering.- 2.5.1 Introduction.- 2.5.2 Experimental requirements for SAXS.- 2.5.3 Outline of the theory of SAXS.- 2.5.4 Some applications of SAXS.- 2.6 The Radial Distribution Function for Amorphous Polymers.- References.- 3 Relaxation Processes in Amorphous Polymers.- 3.1 Introduction.- 3.2 Molecular Motion in Polymeric Melts and Glasses.- 3.2.1 General description of relaxational processes.- 3.2.2 Relaxational processes at the crystal melt temperature.- 3.2.3 Relaxations in the amorphous state above Tg and below Tm.- 3.2.4 Relaxational processes at the glass transition.- 3.2.5 Relaxations in the glassy state.- 3.3 Secondary Relaxation Regions in Typical Organic Glasses.- 3.3.1 Secondary relaxation regions in Polyvinylchloride.- 3.3.2 Secondary relaxation regions in polystyrene.- 3.3.3 Secondary relaxations in polymethylmethacrylate.- References.- 4 Creep in Glassy Polymers.- 4.1 Introduction.- 4.2 Phenomenological Theory of Creep.- 4.2.1 Linear theory.- 4.2.2 Nonlinear theory-creep equations.- 4.2.3 Nonlinear theory-superposition rules.- 4.3 Apparatus and Experimental Methods.- 4.3.1 General principles.- 4.3.2 Special experimental requirements.- 4.3.3 Special experiments.- 4.4 Creep Phenomena in Glassy Polymers.- 4.4.1 Typical creep behaviour.- 4.4.2 Creep at elevated temperatures.- 4.4.3 Creep in anisotropic samples.- 4.4.4 Recovery behaviour.- 4.4.5 Creep under intermittent stress.- 4.4.6 Creep under abrupt changes of stress.- 4.5 Final Comments.- References and Bibliography.- 5 The Yield Behaviour of Glassy Polymers.- 5.1 Introduction.- 5.2 Exact Definitions.- 5.2.1 Stress.- 5.2.2 Strain.- 5.2.3 The deformation-rate tensor.- 5.2.4 The yield point.- 5.2.5 Nomenclature for deformation processes.- 5.3 Mechanical Tests.- 5.3.1 The tensile test.- 5.3.2 The uniaxial compression test.- 5.3.3 The plane strain compression test.- 5.3.4 Tests in simple shear.- 5.3.5 Machine elasticity.- 5.3.6 Drawing at constant load.- 5.4 Characteristics of the Yield Process.- 5.4.1 The yield point and the yield stress.- 5.4.2 The yield strain.- 5.4.3 Strain softening and orientation hardening.- 5.4.4 The strain-rate dependence of the yield stress.- 5.4.5 The temperature dependence of the yield stress and the yield strain.- 5.4.6 The effect of hydrostatic pressure on the yield stress and yield strain.- 5.4.7 The effect of polymer structure on the yield stress.- 5.4.8 Volume changes at yield.- 5.4.9 The Bauschinger effect.- 5.5 Inhomogeneous Deformation.- 5.5.1 The reasons for inhomogeneous deformation.- 5.5.2 The principle of maximum plastic resistance.- 5.5.3 The geometry of inhomogeneous deformation.- 5.5.4 Strain inhomogeneities in polymers.- 5.6 Structural Observations.- 5.6.1 Birefringence.- 5.6.2 Electron microscopy.- 5.7 Yield Criteria for Polymers.- 5.7.1 The Tresca yield criterion.- 5.7.2 The von Mises yield criterion.- 5.7.3 The Mohr-Coulomb yield criterion.- 5.7.4 The modified Tresca criterion.- 5.7.5 The modified von Mises criterion.- 5.7.6 Choice of a yield criterion for polymers.- 5.8 Molecular Theories of Yielding.- 5.8.1 Reduction of the Tg by the applied stress.- 5.8.2 Stress-induced increase in free volume.- 5.8.3 Break-down of entanglements under stress.- 5.8.4 The Eyring model.- 5.8.5 The Robertson model.- 5.8.6 The theoretical shear strength-Frank's modification of the Frenkel model.- 5.8.7 Disclinations.- References.- 6 The Post-Yield Behaviour of Amorphous Plastics.- 6.1 General.- 6.2 The Phenomena of' strain Softening'.- 6.2.1 Stress hardening.- 6.3 Plastic Instability Phenomena.- 6.3.1 Plastic instability in tension.- 6.3.2 Plastic instability in different stress fields.- 6.4 The Adiabatic Heating of Polymers Subject to Large Deformations.- 6.4.1 Reversible thermoelastic effect.- 6.4.2 Thermal effects in large plastic deformation.- 6.4.3 The experimental measurement of temperature changes during deformation.- 6.5 Orientation Hardening.- 6.5.1 Orientation hardening as a physical process.- 6.5.2 Factors affecting orientation hardening.- 6.5.3 A model for large polymer deformations.- 6.6 Large Deformation and Fracture.- 6.6.1 Crack propagation as a deformation process.- 6.6.2 Crazing as a plastic instability phenomenon.- 6.6.3 The growth of voids in a polymer glass.- 6.6.4 The nucleation of voids.- References.- 7 Cracking and Crazing in Polymeric Glasses.- 7.1 Introduction.- 7.2 Fracture Mechanics.- 7.2.1 Linear fracture mechanics.- 7.2.2 Measurements of KIC for glassy polymers.- 7.2.3 Crack-opening displacement.- 7.2.4 Energy balance approach.- 7.2.5 Measurements of surface work.- 7.2.6 Fracture stress.- 7.3 Fatigue Fracture.- 7.3.1 Fatigue failure by heat build-up.- 7.3.2 Fatigue crack propagation.- 7.4 Crazing.- 7.4.1 Crazing of glassy plastics in air.- 7.4.2 Environmental crazing.- 7.4.3 Theoretical aspects.- 7.5 Molecular Fracture.- 7.5.1 Kinetic theories of fracture.- 7.5.2 Experimental evidence for bond fracture.- 7.6 Conclusion.- References.- 8 Rubber ReinForced Thermoplastics.- 8.1 Introduction.- 8.2 Rubber Reinforced Glassy Polymers of Commercial Importance.- 8.2.1 Based on polystyrene.- 8.2.2 Based on styrene acrylonitrile copolymer (SAN).- 8.2.3 Based on Polyvinylchloride.- 8.3 Methods of Manufacture.- 8.3.1 Physical blending.- 8.3.2 Interpolymerisation process.- 8.3.3 Latex interpolymerisation.- 8.4 Incompatibility in Polymer Mixtures.- 8.5 Identification of Two Phase Rubber Reinforced Systems.- 8.6 Dispersed Phase Morphology.- 8.6.1 Toughened polystyrene.- 8.6.2 ABS copolymers.- 8.6.3 Polyvinylchloride.- 8.7 Optical Properties.- 8.7.1 Matching of the refractive index.- 8.7.2 Reduction in particle size.- 8.8 Mechanical Properties.- 8.8.1 Tensile properties.- 8.8.2 Dynamic mechanical properties.- 8.8.3 Impact properties.- 8.8.4 Structure-property relationships.- References.- 9 The Diffusion and Sorption of Gases and Vapours in Glassy Polymers.- 9.1 Introduction.- 9.2 Ideal and Non-ideal Sorption and Diffusion of Fixed Gases.- 9.2.1 Ideal diffusion and sorption of fixed gases.- 9.2.2 Non-ideal sorption and diffusion of fixed gases.- 9.3 The Effect of the Glass Transition on Gas and Vapour Diffusion in Polymers.- 9.4 Relaxation Controlled Transport and Related Crazing of Polymeric Glasses by Vapours.- 9.4.1 Introduction ..- 9.4.2 Relaxation controlled transport and solvent crazing.- 9.5 Some Effects of Crystallinity and Orientation on the Transport of Gases and Vapours in Glassy Polymers.- 9.5.1 Effect of crystallinity.- 9.5.2 The effect of orientation.- References.- 10 The Morphology of Regular Block Copolymers.- 10.1 Introduction.- 10.1.1 General.- 10.1.2 Microphase separation.- 10.2 Techniques Used for the Study of the Morphology of Block Copolymers.- 10.2.1 Low angle X-ray scattering.- 10.2.2 Electron microscopy.- 10.2.3 Other techniques.- 10.3 Variables Controlling the Morphology.- 10.3.1 Chemical variables.- 10.3.2 Physical variables.- 10.4 Studies with Specific Systems.- 10.4.1 Systems with liquid.- 10.4.2 The pure copolymers.- 10.5 Theories of the Morphology of Block Copolymers.- 10.5.1 Objectives.- 10.5.2 Principles of calculation.- 10.6 Implications of Theories and Comparison With Experiment.- 10.6.1 Influence of block molecular weight ratio.- 10.6.2 Effect of block molecular weights.- 10.6.3 Molecular orientation in the phases.- 10.6.4 Interfacial region.- 10.6.5 Effect of temperature on domain size.- 10.7 Mechanical Properties and Deformations.- 10.8 Crystallinity.- References.- Appendix I Glass Transition Temperatures and Expansion Coefficients for the Glass and Rubber States of some Typical Polymeric Glasses.- Appendix II Conversion Factors for SI Units.