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) if this 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

a. Yes it is possible the linear and isotatic material will hae higher tensile strength. both linerity ad isotacity favour a higher degree of crstallinity the do branching and attcity. and tensile stregth increases with increasing degree of rystalinity. further more molecular weight of linear aterial is higher.(25000g/mol to 200000g/mol).

b. No it is not possible alternating copolymers tend to be more crystalllline.then graft copolymers and tensile strength increases with degree of crystallinity. however graft aterial has higher degree of crystallinity and tensile stregth increases with percentage of cross links.

c. yes it is possible network of polyester will display greater tensile strength relative chain motion is much more restricted then for highly branched polymer since there are may of strong covalent bonds for network structre.

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