Elastomers: Styrene Butadiene Rubber(SBR), Poly Butadiene (Part - 1) | Chemical Technology - Chemical Engineering PDF Download

Elastomers: Styrene Butadiene Rubber (Sbr), Poly Butadiene, Nitrile Rubber 

Elastomers are used in wide variety of industrial, medical and household products and major portion of elastomers consumption goes into tyres next largest product sector is latex goods. There are two major types of elastomers; natural rubber a product of tropical tree Hevea brasiliens is and synthetic rubber- a family of materials derived from petrochemical feed stocks . Major producers of natural rubber are natural rubber producing country are Thailand, Indonesia and Malaysia, Africa, Latin America, Brazil, Cambodia, Nigeria, Sri Lanka, Thailand, India.

Demand for natural is estimated to have been around 10.9 million tones in 2011 out of which around 45 percent was from Asia. About 92 percent of natural rubber is produced from Asian countries. The demand for natural rubber globally is projected to grow by 3-4 percent through 2013 .  Synthetic rubbers have slowly replaced natural rubbers and have undergone various developments for applications in automotives, chemical industry, energy generation, sports, aerospace industry etc.

Naturalandsyntheticrubber

1525 Elastic ball reported by Mexico tribal people

1735 First scientific study of rubber by Charles de la Condamine

1820 First planting of rubber in India at Travancore

1832  Rosburg factory was set up for rubber goods with non –vulcanized rubber

145 R.W Thomson invented the Pneumatic tire

1902 First commercial plantation

1910 First large scale commercial production of butadiene rubber

1914-18 Methyl isoprene rubber in Germany

1930 Organic po lysulphide ru bber

1931 Neoprene production started

1932 First synthetic rubber plant in USSR

1933 BUNA-S made in USSR

1936 First automatic tyre factory (Dunlop) in India

1963 First synthetic rubber plant in India

1976 First nitrile rubber by Synthetics Chemicals

1978 First polybutadiene plant in India by IPCL

Petro based synthetic rubber 20 percent India, 80 percent in developed countries. Annual growth rate7 percent 

Natural Rubber  

Christopher Columbus voyage to Haiti 1496

Tree: Cau-achu  Weeping wood

Priestley (1770), Rubber Rub-off

1839 Vulcanising of Rubber

1840 Henry Wickham smuggled 70,000 Herca tree seed to England planted at London. 

Synthetic Rubber 

With the availability of petrochemical feedstocks there has been tremendous increase in the production of synthetic rubber. World synthetic rubber market and its production is given in Figure M-VIII 4.1 and Figure M-VIII 4.2 respectively. Synthetic rubber may be classified as general purpose rubber, specialty rubbers, thermoplastic rubber or liquid processing rubber (eg. silicon rubber, liquid polysulphide rubber). Classification of synthetic rubber is given in MVIII 1.4. Forecast of synthetic rubber and natural rubber consumption in India is given in Table M-VIII 4.3. 

Table M-VIII 4.1: Synthetic and Natural rubber consumption scenario 

Source: IISRP (2011) TSRC Corporation 

Capacity (2011) by Region (15,965 kmta) Consumption (2011) by Region (14,540 mta)
 Figure M-VIII 4.1: World Synthetic Rubbers Market by Region

Figure M-VIII 4.2: World Rubber Production
 

Table M-VIII 4.3: Indian Consumption of Synthetic Rubber (SR) and Natural  Rubber (NR) Forecast 

                                                                                                                                                                          Unit: 000’ metric ton 

SBR is made by emulsion polymerisation at 50oC. Initiation occurs through reaction of potassium peroxydisulphate with n-dodecyl mercaptan. Chain propagation occurs by the growing chain free radical of mercaptyl attaching either butadiene or styrene. The reaction is terminated at 60-75 percent of completion. Unreacted butadiene and styrene were recovered. Antioxidant is added followed by coagulation, washing and drying. It is used as elastomer, emulsion and solution. Used in tyres and tyre-related product, mechanical goods, automotive uses, adhesive, shoe products.

Styrene Butadiene Styrene Rubber (Sbr)  

SBR is a hard rubber which is uses for soles of shoes, tire treads and other places where durability is important. It is a type of copolymer called a block copolymer. Its backbone chain is made of three segments- first segment polystyrene, second polybutadiene and third polystyrene. Polystyrene is tough hard plastic and this gives SBS its durability. Process flow diagram of SBR Manufacture is given in Figure M-VIII 4.2

Figure M-VIII 4.2: Process flow Diagram of SBR Manufacture