Multiple choice

Which of the following statements are false regarding Styrene–Butadiene Rubber (SBR)?

P. SBR is produced by the free-radical polymerization of styrene and butadiene. Q. Cold SBR is better suited to adhesive formulation than hot SBR. R. Tire treads made from emulsion SBR are superior to those from solution SBR. S. The ozone resistance of SBR is superior to that of natural rubber.

Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. Q and S
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hot SBR is better suited to adhesive formulation than cold SBR. Hot SBR has a lower molecular weight and a broader molecular weight distribution than cold SBR. The lower molecular weight fraction provides quick stick, while the higher molecular weight fraction provides shear strength. On the other hand, narrow molecular weight distribution and higher trans structure of cold SBR make it less adaptable to adhesives.

Tire treads made from solution SBR are superior to those from emulsion SBR. Solution SBR has a higher molecular weight, narrower molecular weight distribution, and higher cis -1,4-polybutadiene content than emulsion SBR. These qualities reduce tread wear and enhance crack resistance of the tire.

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