5. Introduction
▰ SBR is an elastomer that was originally developed
during WW2 as a replacement for natural rubber.
▰ It is a copolymer belonging to the family of synthetic
rubbers derived from styrene and butadiene.
▰ SBR has good abraision resistance.
▰ Initially, it was marketed by the name of Buna S.
▰ The properties of SBR depends upon the
styrene/butadiene ratio.
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7. Introduction
▰ Butadiene is obtained as a by-product of naphtha
cracking during the production of ethylene.
▰ Styrene is obtained by the dehydrogenation of ethyl
benzene by Dow’s process.
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9. Synthesis
▰ There are two types of SBR depending upon the
method of synthesis or manufacturing:
▻ E-SBR
It is produced by Emulsion Polymerization
▻ S-SBR
It is produced by Solution Polymerization.
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10. Emulsion Polymerization
▰ The manufacturing of E-SBR is carried out by free
radical mechanism.
▰ The polymerization is initiated by free radicals.
▰ ”Reaction vessels are typically charged with the two
monomers, a free radical generator, and a chain
transfer agent such as an alkyl mercaptan.”
▰ “Radical initiators include potassium
persulphate and hydroperoxides in combination with
ferrous salts. Emulsifying agents include
various soaps.”
▰ Mercaptan controls the molecular weight and viscosity
of the product. 10
11. Solution Polymerization
▰ Solution-SBR is produced by an anionic
polymerization process.
▰ Polymerization is initiated by alkyl lithium
compounds.
▰ “All components are dissolved, which provides
greater control over the process.”
▰ “The organolithium compound adds to one of the
monomers , generating a carbanion that then adds to
another monomer, and so on.”
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12. Manufacturing at large scale
▰ SBR is produced by the copolymerization of
Butadiene and Styrene by emulsion polymerization in
3 : 1 weight ratio.
▰ Purification of recycled and fresh monomers
▰ Heating, water cooling and refrigeration in stainless
steel reactors
▰ Reactors are equipped for both hot and cold SBR
▰ Cold SBR is produced at 5°C and 1 atm gage by
refrigeration techniques
▰ Hot SBR is manufactured at 50°C , and 3-4 atm gage.
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14. Manufacturing at large scale
▰ The polymerization product is then stripped with
chemical inhibitors and the latex resulting from the
reactors is collected in blow down tanks.
▰ The latex is then sent to a falling film stripper to
remove the butadiene.
▰ The bottoms are fed to a perforated plate column
where styrene is stripped out.
▰ Colloid Mill reduces the particle size in emulsions.
▰ Coagulation Conversion is done to avoid clots.
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17. Solution or Emulsion SBR for Tire Manufacturing?
▰ For tire manufacture, S-SBR is increasingly favoured.
▰ It offers improved wet grip and reduced rolling
resistance.
▰ It translates to greater safety and better fuel
economy, respectively.
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19. Grades and Commercial Availability
▰ “The grades of SBR depends upon the styrene
content as well as the Mooney's viscosity.”
▰ “The commercial availability is also based upon
Mooney’s viscosity.”
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23. Properties
▰ “SBR lacks the self-reinforcing qualities of
natural rubber.”
▰ “It is poor conductor of electricity as it’s electrical
conductivity depends upon emulsifier.”
▰ “E-SBR is resistant to polar solvents such as
acids and base.”
▰ “They swell considerably when in contact with
gasoline, fats and oils.”
▰ “While S-SBR with random distribution of
styrene has greater abrasion resistance and
better electrical properties then E-SBR.”
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25. Prediction of the Styrene Butadiene Rubber
Performance by Emulsion Polymerization
▰ “The research deals with the prediction of SBR
performance.”
▰ “The performance was determined by the amount of
initiator used.”
▰ “The effect of styrene content upon the Mooney’s
viscosity was also determined.”
▰ “The polymerization rate of butadiene styrene rubber
can be accelerated by 30% via increasing the initiator
and emulsion amount.”
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27. Conclusion
▰ “SBR belonging to the family of synthetic rubber have
good abrasion resistance and aging stability with
additives.”
▰ “50% tires around the world are made up of various
SBR grades.”
▰ “The properties depends upon styrene/butadiene
content as well as Mooney’s viscosity.”
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28. References
▰ “L. Shulai, S. Yan, Z. Liu et al., “In�uence factors of
increasing conversion of emulsion styrene butadiene
rubber,” China Synthetic Rubber Industry, vol. 29, no.
4, pp. 245–249, 2006.”
▰ “G. Martinez Delfa, A. Olivieri, and C. E. Boschetti,
“Multiple response optimization of styrene-butadiene
rubber emulsion polymerization,” Computers and
Chemical Engineering, vol. 33, no. 4, pp. 850–856,
2009.”
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