Synthesis and characterization of natural rubber support of dimethylphosphonate polymer grafts

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Vulcanization systems

Crosslinking of the rubber phase in heterogeneous blends of thermoplastic and rubber components takes place by introducing of curing agents during the mixing process. This causes crosslinking reactions with formation of covalent bonds between network points. Vulcanization of the rubber phase during mixing or dynamic vulcanization has been used to improve physical properties of thermoplastic elastomers (Coran and Patel, 1983; Fischer, 1973; Stricharzuk, 1977; Goettler et al., 1982). A number of curing systems were used to vulcanize the rubber phase. These include sulphur, phenolic, and peroxide cured systems.

Sulphur cured system

Sulphur has been used as a main curing agent. In addition, accelerators such as benzothiazoles, sulfenamides, dithiocarbamates, and amines in combination with activators, such as zinc oxide or stearic acid, are used to shorten curing times and to prevent thermo-oxidative degradation of the rubber. Figure 2.15 shows scheme of the crosslinking reaction of rubber molecules by sulphur vulcanization system.
Reactions of accelerator and activator (i.e., ZnO) causes opening of cyclic molecular sulphur (1). Hence, an active sulphurizing complex is formed (2). This complex is self destroyed, and react with rubber chains leading to a sulphur-bound rubber intermediate (3). The sulphur-bound rubber intermediate thereafter reacts with other rubber chains and causes their crosslinking (4). The polysulphidic links between the rubber chains is consequent.

LIST OF TABLES
LIST OF FIGURES
LIST OF SCHEMES
LIST OF ABREVIATIONS
CHAPTER
1. INTRODUCTION
1.1 Background
1.2 Objectives
1.3 Research Summary
1.4 Expectation of the research
2. LITERATURE SURVEY
2.1 Introduction
2.2 Chemical modification of natural rubber
2.3 Graft copolymer
2.4 Thermoplastic elastomers (TPEs)
2.5 Thermoplastic natural rubber (TPNR)
2.6 Compatibilization in polymer blend
3. EXPERIMENT
3.1 Materials
3.2 Instruments
3.3 Experiments
3.4 Preparation of test specimens
3.5 Testing and characterization
4. RESULTS AND DISCUSSION
PART A: SYNTHESIS AND CHARACTERIZATION OF NATURAL RUBBER SUPPORT OF DIMETHYLPHOSPHONATE POLYMER GRAFTS
4.1 Monomer synthesis
4.2 Synthesis of NR-g-PDMAMP, NR-g-PDMMEP and NR-g-PDMMMP
4.2.1 Synthesis and characterization of NR-g-PDMAMP and NR-g-PDMMEP
4.2.2 Synthesis and characterization of NR-g-PDMMMP
PART B: PREPARATION OF SIMPLE BLEND BASED ON NR/EVA
4.3 Thermodynamic of NR/EVA blends
4.4 Effect of different types of compatibilizers on properties of NR/EVA blends
4.5 Effect of grafting rate of NR-g-PDMMMP on properties of NR/EVA blend
4.6 Effect of concentration of graft copolymer
PART C: THERMOPLASTIC VULCANIZATES (TPVs)
4.7 Effect of blend compositions on properties of NR/EVA..TPVs
4.8 Effect of vulcanization systems on dynamically cured 40/60 NR/EVA blends
4.9 Effect of different types of compatibilizers
4.10 Effect of concentration of compatibilizer
4.11 Recyclability of dynamically cured NR/EVA blends
5. CONCLUSION
REFERENCES
APPENDIX
BIOGRAPHY