Question

SBR (GRS, Buna-S, cold rubber) is obtained by free radical copolymerization of:
(A) 70% Buta- 1,3- diene and 30% phenyl ethene (styrene)
(B) Chloroprene and styrene
(C) Vinyl acetylene and styrene
(D) Isoprene and 1,3- butadiene

Answer 1

Hint: To answer this question, you must recall the name and the preparation of the given polymeric compound Buna- S. It is known by any other names like, cold rubber, styrene rubber, SBR or GRS. GRS stands for Government controlled styrene rubber. Styrene is one of the two monomers of the given rubber polymer.

Complete step by step solution
SBR stands for styrene butadiene rubber and is named after its monomers butadiene and styrene. SBR describes the entire family of synthetic rubbers that have styrene and butadiene as their monomeric compounds. These polymers have very good abrasion resistance and strong aging stability.
SBR (GRS, Buna-S, cold rubber) is prepared from the free radical co- polymerization of 70% Buta- 1,3- diene and 30% phenyl ethene (styrene).
The correct answer is A.

Note
Styrene butadiene rubber is a rubber polymer and poses a strong competition to natural rubber due to its good elastic strength and abrasion resistance. It is used for the preparation of pneumatic tyres. It is also used in the preparation of shoes (in the heels and soles), sealing gaskets and chewing gums. Buna- S is also used widely in building applications, as a binding or sealing agent as an alternative to polyvinyl acetate. It is costly than PVA but it also provides increased flexibility, reduced shrinkage and thus better durability. It is also highly resistant to emulsification under damp conditions. SBR also has applications in cement based waterproofing systems in which it is mixed with water and added with the slurry. This increases the bond strength of cement and reduces chances of water seeping through.