Question

Which of the following would you expect to be elastomers and which thermosetting polymers at room temperature? (a) Linear and highly crystalline polyethylene (b) Phenol-formaldehyde (c) Heavily crosslinked polyisoprene having a glass-transition temperature of 50oC (122oF) (d) Lightly crosslinked polyisoprene having a glass-transition temperature of -60oC (-76oF) (e) Linear and partially amorphous poly(vinyl chloride)

Answer 1

Answer: Please see below for answer

Explanation:A thermosetting polymer is a polymer that consists a of cross-linked structure or heavily network of branched molecules.

Elastomers are loosely cross-linked polymers which are highly flexible and elastic which can make them stretch easily and return to thier original shapes.

a) Linear and highly crystalline polyethylene is a linear thermoplastic it will not be an elastomer or themoset.

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(b) Phenol-formaldehyde is anetwork structured thermosetting  resin which is regarded  as  the most useful thermosetting resin especially in the production of wood based panels.

(c) Heavily crosslinked polyisoprene having a glass-transition temperature of 50 deg C is a  thermoset since it is heavily cross linked above room temperature.

(d) Lightly crosslinked polyisoprene having a glass-transition temperature of -60 deg C is both an elastomer and thermoset since it has both characteristics .

(e) Linear and partially amorphous poly (vinyl chloride) is a thermoplastic and not  an elastomer or a thermoset.