For the following pairs of polymers, do the following: (1) state whether or not

Question

For the following pairs of polymers, do the following: (1) state whether or not it is possible to decide whether one polymer has a higher tensile modulus than the other; (2) is possible, note which has the higher tensile modulus and then cite the reason(s) for your choice; and (3) if it is not possible to decide, then state why. [Also consider their repeat unit structure] Branched polyethylene with a number-average molecular weight of 250,000 g/mol; linear and isotactic poly(vinyl chloride) with a number-average molecular weight of 200,000 g/mol

Explanation / Answer

No, it is not possible. Branched polyethylene will tend to have a low degree of crystallinity since branched polymers don't normally crystallize. Tensile modulus increases with degree of crystallinity, and it is not possible to determine which polymer is more crystalline. Furthermore, tensile modulus is independent of molecular weight.

Yes, it is possible. Linear polymers are more likely to crystallize and isotactic structures have higher degree of crystallinity.Tensile modulus is a function of crystallinity.In addition, tensile modulus is independent of molecular weight.

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