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tensile modulus increases. (e) A drawn semicrystalline polymer that is annealed experiences a decrease in tensile modulus as a result of a reduction in chain-induced crystallinity, and a reduction in interchain bonding forces. 15.17 For each of four pairs of polymers, we are to do the following: 1) determine whether or not it is possible to decide which has the higher tensile modulus; 2) if it is possible, then note which has the higher tensile modulus and then state the reasons for this choice; and 3) if it is not possible to decide, then state why. (a) No, it is not possible. Both syndiotactic and isotactic polystyrene have a tendency to crystallize, and, therefore, we assume that they have approximately the same crystallinity.
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