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Chapter 4 - Rubber, Latex is obtained by cutting the bark of rubber tree -…

- - - - increasing these properties
        
        Tensile strength
        
        Elasticity
        
        Hardness
        
        Tear strength
        
        Abrasion resistance
        
        Resistance to solvents
  - - - Thermoplastic
      - Soft & sticky
      - Low tensile strength
      - Low wear & tear resistance
      - Large water absorption capacity
      - Low resistance to abrasion
      - Can be used over narrow temperature range
      - Soluble in organic solvents
    - - Thermoset
      - Hard & non-sticky
      - High tensile strength
      - High wear & tear resistance
      - Low water absorption tendency
      - High resistance to abrasion
      - Insoluble in most organic solvents
      - Can be used over wide temperature range
- - - - Thermolast
      - Hipex
      - Copec
      - Santoprene
      - Termoton
  - - - Copolymer - Isobutylene isoprene rubber
      - Produced by the polymerization of ~98% isobutylene with ~2% isoprene
      - Excellent impermeability and good flexibility
      - Rubber stopper for medicine vials, chewing gums, tire inner tube, sealants, gas mask and other protective clothing
    - - Poly(styrene-butadiene-styrene)
      - Used to make shoe soles, tire treads and other durable products
    - - Obtained by free radical polymerization of isoprene
      - All formed rubber has trans configuration
      - Has highly zig zag chain which cannot be stretch
      - Non elastic
    - - Polychloroprene produced by polymerization of chloroprene
      - High tensile strength, resilience, oil and flame resistance, degradation resistance
      - High cost
      - Used in manufacture
        of hoses, gaskets, shoe heels and insulator
    - - obtained by co-polymerization of 1,3-Butadiene and acrylonitrile in presence of peroxide catalyst
      - Resistant to petrol, lubricating oils and organic solvents
      - Used in making oil seals, hoses and tank linings