These were among the first speciality rubbers with reasonably good resistance to hot oils and aggressive lubricants. The main use for the dry rubber is in the auto industry for O-rings, oil seals and gaskets. There are also important applications for the lattices in textile coating, papermaking and leather finishing.

Polybutadiene can be produced by both emulsion and solution polymerisation. Emulsion polymers are of random nature in stereospecificity. Solution polymers can be manufactured into stereospecifically tailor-made forms. It is achieved with the use of different catalysts such as anionic or ziegleratta type. BR has excellent resilience, abrasion resistance, and low temperature flexibility. BR can have higher filler loading and oil extension without property deterioration. Tear strength and resistance to cut growth are relatively poor for BR and hence is used as a blend with other rubbers. About 90% of BR is used in tyres, blended in various proportions with SBR, NR etc. Other application of BR is as an additive in rigid plastics such as polystyrene for impact modification. Other engineering applications such as V-belts, conveyor belting, solid rubber tyres, antivibration mounting roller covering and flexible heavy duty suction and discharge hoses. 

Styrene - Butadiene Rubber (SBR)

SBR is the largest tonnage synthetic rubber being made all over the world. It accounts for about 60% of the synthetic rubber production and more than 30% of all the rubber consumed. It is a copolymer of butadiene and styrene. The most common SBR is having approximately 25% styrene and 75% butadiene with a random distribution of monomers. There are about 500 grades of this rubber including a large proportion of oil-extended forms and masterbatches of SBR with carbon black. SBR exhibits good abrasion resistance and hence its major application is in tyre sector, especially in passenger car tyres. Other important applications include soles and heels for the footwear, floorings, mats and other domestic items, conveyor belting, hose, rollers, cycle tyres, buffers, gaskets and a large number of other industrial components. About 90% of the SBR produced is by emulsion polymerisation and the rest by solution polymerisation. In addition, about 10% of all the SBR produced is marketed in latex form and is used for applications such as carpet backing, paper coating and latex foam. There is also a small but growing quantity used in adhesives such as butadiene styrene vinyl pyridine for making tyre cord adhesives.

Silicone Rubber (Q)

Silicone rubbers differ from other synthetic elastomers primarily because they are not organic carbon compounds. Instead of a chain of carbon atoms, the backbone of their molecules is made up of alternate atoms of silicone and oxygen. Physical properties are relatively poor at room temperatures, but they retain their strength and elasticity over a much wider range of temperature than hydrocarbon rubbers. In addition, they have good electrical properties, resistance to aging, weathering and ozone. They also have excellent colour consistency. Their most important uses are in the aerospace industry and other branches of sophisticated engineering, where they provide seals and electrical insulation capable of withstanding working temperature as low as –100oC and as high as 200oC or even higher. Chemically they are extremely inert, and they have the valuable stick property common to most silicones. Silicones, therefore, are used for conveyor belting in the food processing and confectionery industries, for pharmaceutical stoppers, and in surgical applications for blood transfusion tubing, artificial heart valves, dialytic membranes in kidney machine, cable insulation and seals. 

Polyurethane (EU/AU) 

Polyurethanes differ from most other rubbers in that they do not necessarily have to be vulcanised, though some vulcanizable types are available for processing on ordinary rubber manufacturing machinery. As solid rubbers, they have great strength and abrasion resistance, and good resistance to oil and to all forms of oxidation. They are used for roller covering – especially printers rollers – solid tyres, gear wheels, and other engineering components. Polyurethane is used for fabric coatings and synthetic leathers and for very fine type of elastic thread. The main use of polyurethane is in foam. The flexible foam is extensively employed for upholstery, both in vehicles and in furniture, and in foam-backed textiles. Semi-rigid foams are mostly used for safety padding in autos. Rigid foams provide heat insulation in buildings and core material for sandwich construction.

Fluoro Rubbers (CFM)

The fluoro-carbon and fluoro-silicone rubbers are among the most expensive elastomers in the market. Their main function is to provide oil seals and hose capable of withstanding hot lubricants and hydraulic fluids at temperature of 200oC and beyond and hence are mainly being used in aerospace industry. They also have very good electrical characteristics combined with low water absorption. 

Ethylene vinyl acetate

(Also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene. It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, barrier properties, low-temperature toughness, stress-crack resistance, hot-melt adhesivewater proof properties, and resistance to UV radiation. EVA has little or no odor and is competitive with rubber and vinyl products in many electrical applications.

Polybutadiene can be produced by both emulsion and solution polymerisation. Emulsion polymers are of random nature in stereospecificity. Solution polymers can be manufactured into stereospecifically tailor-made forms. It is achieved with the use of different catalysts such as anionic or ziegleratta type. BR has excellent resilience, abrasion resistance, and low temperature flexibility. BR can have higher filler loading and oil extension without property deterioration. Tear strength and resistance to cut growth are relatively poor for BR and hence is used as a blend with other rubbers. About 90% of BR is used in tyres, blended in various proportions with SBR, NR etc. Other application of BR is as an additive in rigid plastics such as polystyrene for impact modification. Other engineering applications such as V-belts, conveyor belting, solid rubber tyres, antivibration mounting roller covering and flexible heavy duty suction and discharge hoses.

Chloroprene is a liquid resembling isoprene in chemical structure, except that it has a chlorine atom where isoprene has a methyl group. Because of this, chloroprene rubber or polychloroprene offers greater resistance to oils and solvents than natural rubber or SBR, and to the destructive effects of sunlight, aging and oxidation. Its heat resistance is also good – even above 100oC in suitable compounds. Its resilience is lower than that of natural rubber and decreases fairly rapidly at lower temperature. Its strength and abrasion resistance are good. It has very good properties and is effectively flame proof. It is used in a wide range of applications in the non-tyre sector of the industry. Chloroprene rubber is used for the covering layer in most types of oil hose, and frequently for the lining through which the oil flows. It is used in mechanical rubbers when heat resistance is required and the changes of oil contact is likely. It is used for seals, strip and other components in the automotive industry, window gaskets, and roofing sheet in buildings, bridge and building bearing pads, chemical plant lining and electric cable covering. Other applications include the water proofing of textiles and tarpaulins, life rafts and inflatable dinghies, and the manufacture of paints.

This is a copolymer of acrylonitrile and butadiene in which the proportion of acrylonitrile may vary from 18 to 40%. Generally speaking higher the proportion of acrylonitrile in the NBR, the poorer the physical properties but better the oil resistance. Compared to chloroprene NBR exhibits higher oil and heat resistance while, sunlight resistance is not as good. Nitrile rubberis used for the production of many kinds of oil, gasoline, solvent hose, oil seals, gaskets, O-rings, brake linings, printing rolls, chemical plant lining, industrial adhesives etc. Blends of nitrile rubber and PVC provide an extremely tough oil and abrasion resistant material for heavy duty cable sheathing and soles on industrial footwear. Nitrile latices, including carboxylated grades, have important applications in paper making and coating, in the manufacture of non-woven fabric, artificial leather, and in finish and waterproofing of real leather.

Butyl Rubber is a solution copolymer of isobutylene with a small proportion (from 1 to 4%) of isoprene. Polyisobutylene by itself is fully saturated, and the isoprene is included to provide sufficient double bonds to allow vulcanisation with sulphur. Its outstanding property is the very low permeability to air and other gases. Low resilience, very good resistance to sunlight, ozone and aging, and relatively good resistance to high temperature are the other specialities. Butyl tends to be incompatible with other rubbers, but this difficulty can be overcome by modifying the polymer with chlorine and bromine to give chlorobutyl and bromobutyl rubbers. The main application for all forms of butyl rubber is to make inner tubes for tyres, and more recently is being used as linings for tubeless industries. Its high heat resistance has lead to its utilization for applications such as steam hose and the curing bags used in tyre vulcanisation. Sunlight and weather resistance of butyl is exploited in roofing membranes and reservoir sheeting. Its chemical resistance is made use of in anticorrosion linings.

Idea of synthetic alternative to natural rubber and its development took place during eth 20th century. The initial development of the industry was closely associated with the demands of the 1st and 2nd world war. While natural is a gift of nature, synthetic rubbers are made in the chemical plants, using the raw materials mostly from the petroleum industry. Important raw materials being used for the production of synthetic rubber are butadiene, styrene, isoprene, chloroprene, isobutylebe, acrylonitrile, ethylene, and propylene. Depending on the quantity and type of the monomer used, conditions of polymerisation and the end use requirement, different tailormade forms of synthetic rubbers can be made. Following are the commercially important synthetic rubber.