Type of Rubbers:
Natural rubber has remarkable elasticity and it undergoes long-range reversible extensions.
- It is manufactured from latex-latex is obtained from bark trees.
Structure: Chemically natural rubber is a linear 1,4-addition polymer of isoprene (2-methyl-1, 3-Butadiene)
Natural rubber is very soft and brisk. It has high water absorption capacity and low tensile strength.
- Its properties can be improved by a process called vulcanization. It is consisting of heating raw rubber with Sulphur at 373-415 k to increase the rate of reaction zinc oxide is added.
- During vulcanization Sulphur bridges are or cross-links between polymer chains are introduced either at their reactive allylic position or at double bond site.
- Thus, due to vulcanization rubber becomes hard and stronger and remove tackiness of natural rubber.
These may be defined as vulcanizable rubber like polymers which is capable of getting stretched twice to its length.
- Neoprene: It is polymer of chloroprene (2-chloro, -1,3-butatiene)
- It is used in the manufacture of noses, gaskets.
- It is used as an insulator and for making conveyor belts and printing rollers.
It is a rubber obtained by copolymerization of 1,3-butadiene and acrylonitrile in presence of peroxide catalyst.
- It is resistant to the action of petrol, lubricating oils and organic solvents, it is used for making oil seals, hoses and tank linings.
It is prepared by copolymerization of 1,2-dichloroethane with sodium tetra sulphide [Na2SO4] in presence of Mg(OH)2