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  • TITLE
  • DEDICATION
  • CERTIFICATE
  • DECLARATION
  • ACKNOWLEDGEMENT
  • CONTENTS
  • GLOSSARY OF TERMS
  • 1. Introduction
  • 1.1. Thermoplastic elastomers (TPFs)
  • 1.2. Incompatible blends.
  • Fig.1.1 (a) Interface between immiscible polymers and (b) Interfacial density profile between immiscible polymers
  • Fig.1.2 Phase arrangements in heterogeneous blends during extrusion: (a) side by side (b) sheath core and (c) matrix fibril.
  • 1.3. Compatibilisation concepts.
  • Table 1.1. Polymex blends compatibillsed by different techniques [lo].
  • 1.4. Copolymers as compatibilisers.
  • 1.5. Theoretical aspects of compatibilisation.
  • 1.6. Compatibilisation of thermoplastic elastomers.
  • 1.7. Scope of the work.
  • 1.8. Objectives.
  • 1.8.1. Miscibility and phase separation behaviour in solution
  • 1.8.2. Effect of graft copolymer concentration on solid state morphology.
  • 1.8.3. Rheological properties.
  • 1.8.4. Mechanical properties.
  • 1.8.5. Thermal properties.
  • References.
  • 2. Experimental Techniques
  • 2.1. Materials.
  • 2.1.1. Natural rubber (NR)
  • 2.1.2. Poly (methyl methacrylate) (PMMA)
  • 2.1.3. Graft copolymer (NR-g-PMMA)
  • Table 2.1. Characteristics of the polymers.
  • 2.1.4. Solvents.
  • 2.1.5. Chemicals.
  • 2.2 Preparation of the blends.
  • 2.2.1. Solution cast blends.
  • 2.2.2. Melt mixed blends.
  • 2.3. Morphology of the blends.
  • 2.4. Viscosity measurements.
  • 2.5. Phase separation experiments.
  • 2.6. Mechanical properties.
  • 2.6.1. Tensile strength.
  • 2.6.2. Tear strength.
  • 2.6.3. Izod impact strength.
  • 2.6.4. Morphology of the failure surface.
  • 2.7. Rheological properties.
  • 2.7.1. Measurements.
  • 2.7.2. Extrudate swell.
  • 2.7.3. Melt flow indices.
  • 2.7.4. Morphology of the extrudate.
  • 2.8. Thermal analysis.
  • 2.8.1. Dynamic mechanical analysis.
  • 2.8.2. Differential scanning calorimetry.
  • 2.8.3. Thermogravimetry (TG)
  • References.
  • 3. Miscibility, Phase Separation and Compatibilisation Effects in Solution
  • 3.1. Miscibility studies by viscometry.
  • Table 3.1 Experimental and calculated values of [q] for NWPMMAblends.
  • Fig.3.4. Experimental and calculated inhinsic viscosities (111 of WMMApolymer blends.
  • 3.2. Heat of mixing and compatibility.
  • Fig.3.7. Heat of mixing (AH) versus weight percentage of PMMA in the blend.
  • 3.3. Polymer / polymer and polymer blend / solvent interactions.
  • Table 3.2. Interaction parameters for polymer-polymer system.
  • Table 3.3. Interaction parameters for polymer blend-solvent system (toluene)
  • 3.4. Phase separation behaviour.
  • 3.4.1. Effect of graft copolymer concentration.
  • 3.4.2. Effect of nature of solvent on phase separation.
  • 3.4.3. Effect of mode of addition on phase separation.
  • 3.4.4. Effect of graft copolymer / homopolymer molecular weight on phase separation.
  • References.
  • 4. Compatibilising Effect of Graft Copolymers on the Solid State Morphology
  • 4.1. Effect of graft copolymer concentration on morphology.
  • Fig.4.1. Optical photornicrographs of 50/50 NR/PMMA blend with and without graft copolymer (a) 0 % graft and (b] 15% graft.
  • Fig.4.2. Scanning electron micrographs of 50/50 NR/PMMA blends: (a) 0% graft. (b) 5% graft, (c) 10% graft and (d) 15% graft.
  • Fig.4.3. Effect of graft copolymer concentration on the domain size of thedispersed phase of different NR/PMMA blends.
  • Fig.4.4. Effect of graft copolymer concentration on interparticle distance of the dispersed phase in 50/50 NR/PMMA blend.
  • 4.2. Effect of homopolymer molecular weight on morphology.
  • 4.3. Effect of graft copolymer on particle size distribution.
  • Fig.4.5 Influence of molecular weight of NR on morphology.
  • Fig.4.6 Effect of molecular weight of natural rubber on CMC
  • Fig.4.7. Effect of copolymer concentration on domain size distribution 50/50 NR/PMMA blend.
  • 4.4. Effect of casting solvents on morphology.
  • 4.5. Effect of mode of addition of graft copolymer on morphology.
  • Fig.4.8. Speculative model representing the behaviour of copolymer having different mode of mixing.
  • 4.6 Discussion.
  • Fig.4.9 Effect of graft copolymer volume fraction on particle size reduction.
  • Table 4.1. Dispersed phase diameter (2R) at CMC and a values of the system.
  • References.
  • 5. Melt Rheological Properties
  • 5.1. Effect of blend ratio and shear stress on viscosity.
  • Fig.5.2. Variation of shear viscosity with weight percentage of NR in W M M Asolution cast blends at different shear rates.
  • Fig.5.3. Speculative model illustrating the structure development of PMMA domains at a shear rate of (a) 33.3 s-1and (b) 833.3 s-1
  • Fig.5.4. Experiment and theoretical values of shear viscosity as a function of weight per cent of NR at a shear rate of 333 S-1
  • 5.2. Effect of compatibiliser and shear stress on viscosity of 50/50 NR / PMMA blends.
  • Fig.5.7. Scanning electron micrographs of extrudate morphology as a function of graft copolymer concentration of 50/50 NR/PMMA solution cast blends: [a) 0%. (b) 5% and (c) 10% graft copolymer.
  • Fig.5.8. Variation of average domain size as a function of graft copolymer concentration in 50/50 NR/PMMA solution cast blends.
  • Fig.5.9. Variation of interparticle distance as a function of graft copolymer concentration in 50/50 NR/ PMMA solution cast blends.
  • Fig.5.10. Relationship between average diameters and shear viscosity as a function of graft copolymer concentration at a shear rate of 33 s-1
  • 5.3. Comparison between melt and solution mixed blends.
  • Fig.5.11. Variation of shear viscosity with shear stress of 0/100, 50/50, 70/30 and 100/0 NR/PMMA melt mixed blends.
  • Fig.5.12. Variation of shear viscosity with weight percentage of NR in NR/PMMA melt mixed blends at different shear rates.
  • Fig.5.13. Variation of shear viscosity with shear stress of 50/50 NR/PMMA melt mixed blends with 0, 2, 5 and 10% graft copolymer and dicurnyl peroxide vulcanised systems.
  • Fig.5.14. Variation of shear viscosity as a function of graft copolymer concentration of 50/50 NR/PMMA melt mixed blends at different shear rates.
  • 5.4. Effect of temperature on melt viscosity.
  • Fig.5.15. Effect of temperature dependence on the melt viscosity of 50/50 NR/PMMA melt mixed blends with 0, 5 and 10% graft copolymer concentration
  • Fig. 5.16. Arrhenius plot. for NR/PMMA melt mixed blends with 0, 5 and 10% graft copolymer concentration.
  • Table 5.1. Activation energy for 50/50 NR/PMMA melt mixed blends.
  • 5.5. Shear rate temperature super position curve.
  • Fig.5.17. Flow curve of shear stress versus log shear rate at 130, 140 and 150°C.
  • Fig. 5.18. Master curve of modified shear stress versus log shear rate as a function of temperature.
  • Fig.5.19. Variation of shift factor as a function of reciprocal temperature
  • 5.6. Flow behaviour index.
  • Table 5.2. Effect of % of NR on flow behaviour index at 130 0C.
  • Table 5.3. Flow behaviour index of 50/50 NR/PMMA blend as a function of temperature and copolymer loading.
  • 5.7. Deformation of the extrudate.
  • Fig.5.20. Extrudate deformation at different shear rates of NR/PMMA blends as a function of blend ratio and compatibiliser loading.
  • 5.8. Melt elasticity.
  • 5.8.1. Die swell.
  • Table 5.4. Die swell, principal normal stress, recoverable elastic shear strain and shear modulus values of 50/50 NR/PMMA at 333 s-1.
  • 5.8.2. Principal normal stress differences.
  • 5.8.3. Recoverable elastic shear strain (SR)
  • Fig.5.21. Principal normal stress difference with shear rates as a function of graft copolymer concentration.
  • 5.8.4. Elastic shear modulus (G)
  • 5.9. Melt flow indices.
  • 5.9.1. Melt flow index and rheometer data.
  • Table 5.5. MFI values of NR/PMMA solution cast blends.
  • Fig.5.22. Master curve of modified shear viscosity versus modified shear rates as a fundion of graft copolymer concentration at 130°C.
  • 5.10. Influence of processing history on morphology and stability of the blend.
  • Fig.5.23. Scanning electron rnicrogmphs of extndate of 50/50 NR?PMMA blends:
  • References.
  • 6. Mechanical Properties
  • 6.1. Effect of blend ratio on morphology and mechanical properties.
  • 6.1.1. Morphology of the blend.
  • 6.1.2. Mechanical properties.
  • Fig.6.1. Scanning electron rnicrographs of NR/PMM blends: (a) 70/30 (b) 50/50 and (c) 30/70.
  • Fig.6.2. Effect of blend composition on the domain size distribution of 70/30 and50/50 NR/PMMA blends.
  • Fig.6.3 Stress-strain curves of NR/PMMA blends as a function of composition.
  • Table 6.1. Mechanical properties of NR/PMMA blends.
  • Fig.6.4. Effect of weight percentage of NR on tensile and tear strength of NR/PMMA blends.
  • Fig. 6.5. Effect of weight percentage of NR on elongation at break and Youngsmodulus of NR/PMMA blends.
  • 6.1.3. Model fitting.
  • Fig.6.6. Experimental and theoretical values of tensile strength as a function of volume fraction of NR.
  • Fig.6.7. Experimental and theoretical values of tear strength as a function of volume fraction of NR.
  • 6.2. Effect of graft copolymer on mechanical properties.
  • 6.2.1. Tensile properties.
  • Fig.6.8. Stress-strain curves of 50/50 NR/PMMA solution cast blends as a function of graft copolymer concentration.
  • Fig.6.9. Stress-strain curves of 50/50 NR/PMMA melt mixed blends as a function of graft copolymer concentration.
  • Table 6.2. Mechanical properties of 50/50 NR/PMMA blends with graft copolymer.
  • Fig.6.10. Variation of tensile strength and average domain size as a function of graft copolymer concentmtion of 50/50 NR/PMMA blends.
  • 6.2.2. Tear properties.
  • 6.2.3. Izod impact strength.
  • Fig.6.11 Variation of tear strength as a function of graft copolymer concentration on 50/50 NR/PMMA blends cbtained by solution and melt mixing techniques.
  • Fig.6.12 Variation of izod impact strength as a function of graft copolymer concentration on 50/50 NR/PMMA blends obtained by solution and melt mixing techniques.
  • 6.3. Comparison of mechanical properties between melt mixed and solution cast blends.
  • Fig.6.13. Variation of tensile strength as a function of graft copolymer concentration on 50/50 NR/PMMA blends obtained by solution and melt mixing techniques.
  • 6.4. Failure topography.
  • Fig. 6.14. Tensile fractographs of 50/50 NR/PMMA blends: (a) 0%. (b) 5%, (c) 10% and (d) 15% graft copolymer.
  • Fig.6.15. Tear fractographs of 50/50 NR/PMMA blends: (aj 0%. (b) 5% and (c) 10% graft copolymer.
  • References.
  • 7. Thermal Characteristics
  • 7.1. Dynamic mechanical properties.
  • 7.2. Differential scanning calorimetry.
  • 7.3. Thermogravimetry.
  • References.
  • 8. Conclusion and Scope of Future Work
  • 8.1. Conclusion.
  • 8.2. Scope of future work.
  • 8.2.1. Measurement of interfacial tension.
  • 8.22. Interfacial thickness.
  • 8.2.3. Location of the copolymer.
  • 8.2.4. Comparison with block copolymer.
  • 8.2.5. Fabrication of various products.
  • APPENDICES
  • APPENDIX I List of Publications in International Journals
  • APPENDIX II Papers Presented at NationaVlnternationaI Conferences
  • Curriculum Vitae