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TITLE
DEDICATION
CERTIFlCATE-1
CERTIFICATE-2
DECLARATION
ACKNOWLEDGEMENT
SYMBOLS AND ABBREVIATIONS
CONTENTS
1. Introduction
1.1 Introduction
1.2 Incompatibility: problems and solutions
Fig.1.1. (a) Interface between immiscible polymers and (b) Interfacial density profile between immiscible polymers.
1.3 Compatibilisation techniques
Table 1.1. Compatibility through non-readve copolymers.
Table 1.2. Compatibility through reactive copolymers.
Table 1.3. Compatibility through low molecular weight reactive compounds.
1.4 Compatibilisation by block and graft copolymers-basic features
Fig.1.2. Conformation of the copolymer at the blend interface: (a) graft, (b) diblock and (c) triblock copolymers extending into the homopolymers.
1.5 Theories of compatibilisation
1.6 Thermoplastic elastomers (TPEs)
1.7 Compatibilisation studies on thermoplastic elastomer blends
1.8 Scope of the work
1.8.1 Effect of processing conditions on morphology and mechanical properties
1.8.2 Compatibilising action of NR-graft-PS on morphology and mechanical properties
1.8.3 Melt rheological properties
1.8.4 Stress relaxation measurements
1.8.5 Dynamic mechanical thermal analysis
1.8.6 Thermal properties
1.8.7 Swelling studies
1.9 References
2. Experimental Techniques
2.1 Materials
2.1.1 Natural rubber (NR)
Table 2.1. Specifications for ISNR-5 grade NR
2.1.2 Polystyrene (PS)
2.1.3 Graft copolymer (NR-g-PS)
2.1.4 Solvents
Table 2.3. Characteristics of the solvents
2.1.5 Other chemicals
2.2 Preparation of the blends
2.2.1 Melt mixed NR / PS blends
2.2.2 Solution casted NR / PS blends
2.3 Characterisation of blend properties Mechanical properties
2.3.1 Mechanical properties
a) Tensile strength, modulus and elongation at break
b) Tear strength
c) Izod impact strength
2.3.2 Morphology of the blends
2.3.3 Melt flow studies
(a) Rheological measurements
b) Die swell measurements
(c) Extrudate morphologv analysis
d) Melt flow index (MFI)
2.3.4 Stress relaxation studies
2.3.5 Dynamic mechanical thermal analysis
2.3.6 Thermal studies
a) Thermogravimetric analysis (TGA)
(b) Differential scanning calorimetry (DSC)
2.3.7 Swelling studies
2.4 References
3. Effect of Processing Conditions on Morphology and Mechanical Properties
3.1 Results and discussion
3. 1.1 Processing characteristics
3.1.2 Morphology of the blends
Fig. 3.4. Optical micrographs of solution casted 30/70 NR/PS blends. (a) CHCl3, (b) CCl4 and (c) C6H6
Fig. 3.5. Optical micrographs of solution casted 50/50 NR/PS blends (a) CHCl3, (b) CCl4 and (c) C6H6
Fig.3.6. Optical micrographs of solution casted 70/30 NR/PS blends (a) CHCl3, (b) CCl4 and (c) C6H6
Fig.3.10. Scanning electron micrographs of melt mixed NR/PS blends: (a) 30/70, (b) 40/60, (c) 50/50, (d) 60/40 and (e) 70/30 NR/PS blends.
3.1.3 Mechanical properties
3.1.4 Dynamic vulcanisation
Fig.3.19. Schematic representation of blend morphology showing the uniformdistribution of particles upon dynamic crosslinking.
Fig.3.20. Schematic representation of dynamically vulcanised NRIPS blendmorphology (a) 70/30, (b) 30/70 NR/PS blend.
Fig.3.21. Scanning electron micrographs of dynamically cured 30/70 NR/PS blends: (a) sulphur, (b) mixed and (c) peroxide.
3.2 References
4. Compatibilising Effect of Graft Copolymers on Morphology and Mechanical Properties
4.1 Results
4.1.1 Graft copolymer characterisation
4.1.2 Morphological studies
a) Effect of graft copolymer concentration
Fig. 4.3. Optical microphotographs of 50/50 NR/PS blend with (a) 0% (b) 1.5% (c) 3% (d) 4.5% graft copolymer.
(b) Effect of molecular weights of homo and graft copolymers
(c) Effect of mode of addition of graft copolymer
Fig.4.9. speculative model illustrating the compatibilisation efficiency under different mode of addition of copolymer.
d) Effect of casting solvents
Fig.4.10. Optical microphotographs of CCl4 and CHC13 casted films (60/40 NR/PS blend) containing (a) 0% graft, CCl4 (b) 1.2% graft, CC14 (c) 0% graft, CHCI3 (d) 1.2% graft, CHCl3
4.1.3 Mechanical properties
4.2 Discussion
4.3 References
5. Melt Rheological Properties
5.1 Results and discussion
5.1.1 Effect of shear stress and blend ratio on viscosity
Fig. 5.2. SEM photographs of extrudate of 50/50 NR/PS blends (solution casted) at differentshear rates: (a) non-compatibilised at 57.6 sec-I, (b) non-compatibilised at 115.2 set., (c) cornpatibi!ised at 57.6 sec-, and (d) compatibilised at 115.2 sec-l)
Fig.5.5. Speculative model illustrating the structural build up and breakdowr! at low andhigh shear rate region.
Fig.5.6. Schematic representation of the morphology in the absence and presence of acompatibiliser (copolymer)
5.1.2 Effect of processing techniques and blend ratio on viscosity
5.1.3 Effect of compatibiliser loading on viscosity and extrudate morphology
Fig. 5.13. SEM photographs of extrudate of solution casted 50/50 NR/PS blends: (a) 0%, (b) 1.5% and (c) 3% graft copolymer.
5.1.4 Effect of temperature and shear stress on viscosity
5.1.5 Flow behaviour index (n)
5.1.6 Extrudate deformation studies
Fig.5.18. Extrudate deformation at different shear rates as a function of compatibiliser loading (50/50 NR/PS solution casted blends)
Fig.5.19. Extrudate deformation at different shear rates as a function of blend composition (50/50 NR/PS melt mixed and solution casted blends)
5.1.7 Melt elasticity
(a) Die swell
(b) Principal normal stress difference
(c) Recoverable shear strain (SR)
5.1.8 Melt flow index (MFI)
5.2 References
6. Stress Relaxation Studies
6.1 Results and discussion
6.1.1 Effect of strain level
6.1.2 Effect of composition
Fig.6.3. Optical microphotographs of (a) 40/60, (b) 50/50 and (c) 60/40 NR/PS blends.
6.1.3 Effect of compatibiliser loading
6.1.4 Effect of ageing
6.2 References
7. Dynamic Mechanical Properties
7.1 Results and discussion
7.1.1 Effect of frequency
7.1.2 Effect of blend composition
7.1.3 Effect of compatibilisation
7.1.4 Modelling of viscoelastic properties
7.1.5 Cole-cole analysis
7.1.6 Time-temperature superposition
7.2 References
8. Thermal Characteristics
8.1 Results and discussion
8.1.1 Thermogravimetry (TG)
8.1.2 Differential scanning calorimetry studies (DSC)
8.2 References
9. Transport of Aliphatic Hydrocarbon Liquids Through Dynamically Crosslinked NR / PS Blends
9.1 Results and discussion
9.1.1 Effect of vulcanising system
9.1. 2 Effect of penetrant size
9.1.3 Mechanism of sorption
9.1.4 Effect of blend composition
9.1.5 Effect of temperature
9.1.6 Thermodynamic parameters
9.1.7 Comparison with theory
9.2 References
10. Conclusion and Future Outlook
10.1 Conclusion
10.2 Future outlook
10.2.1 Influence of block copolymer on compatibilisation
10.2.2 Interfacial tension measurement
10.2.3 Interfacial thickness measurements
10.2.4 Location of the copolymer
10.2.5 Fabrication of useful products
APPENDIX
List of Publications
I. Papers published in International Journals
II. Other publications (Chapter for a Book)
Ill. Papers presented in lnternational and National Conferences
THE TECHNOLOGICAL COMPATIBILIZATION OF NATURAL RUBBER/POLYSTYRENE BLENDS BY THE ADDITION OF NATURAL RUBBER- graft-POLYSTYRENE
EFFECT OF CASTING SOLVENTS AND COMPATlBlLlZER LOADING ON THE MORPHOLOGY AND PROPERTIES OF NATURAL RUBBER/POLYSTYRENE BLENDS
Curriculum Vitae