Question

For each of the following pairs of polymers, do the following: (1) State whether it is possible to determine whether one polymer is more likely to crystallize than the other; (2) if it is possible, note which is the more likely and then cite reason(s) for your choice; and (3) if it is not possible to decide, then state why.
(a) Linear and atactic poly(vinyl chloride); linear and isotactic polypropylene
(b) Linear and syndiotactic polypropylene; crosslinked cis-polyisoprene
(c) Network phenol-formaldehyde; linear and isotactic polystyrene
(d) Block poly(acrylonitrile-isoprene) copolymer; graft poly(chloroprene-isobutylene) copolymer

Answer 1

Answer:

1). Linear and syndiotactic poly(vinyl chloride); linear and isotactic polystyrene

2). Network phenol-formaldehyde; linear and heavily crosslinked cis-isoprene

3). Linear polyethylene, lightly branched isotactic polypropylene

Explanation:

1). It is very much possible to decide for the two polymers. Here the linear as well as the syndiotactic poly(vinyl chloride) are likely to be crystallize; the side - group  phenyl of the polystyrene is more bulkier than CI side group for the poly(vinyl chloride). The syndiotactic as well as the isotactic isomers are  likely to crystallize equally.

2). No we cannot decide for the two polymers. Both of them are crosslinked and the network polymers may not crystallize.

3). It is a possible to decide the two polymers. The linear polyethylene is likely to crystallize.