Which of the following would you expect to be elastomers and which thermosetting polymers at room temperature? Justify each choice.

(a) Epoxy having a network structure

(b) Lightly crosslinked poly(styrene-butadiene) random copolymer that has a glass-transition temperature of -50(C

(c) Lightly branched and semicrystalline polytetrafluoroethylene that has a glass-transition temperature of -100(C

(d) Heavily crosslinked poly(ethylene-propylene) random copolymer that has a glass-transition temperature of 0(C

(e) Thermoplastic elastomer that has a glass-transition temperature of 75(C