For each of the following pairs of polymers, plot and label schematic specific volume versus temperature curves on the same graph [i.e., make separate plots for parts (a), (b), and (c)].

(a) Spherulitic polypropylene, of 25% crystallinity, and having a weight-average molecular weight of 75,000 g/mol; spherulitic polystyrene, of 25% crystallinity, and having a weight-average molecular weight of 100,000 g/mol

(b) Graft poly(styrene-butadiene) copolymer with 10% of available sites crosslinked; random poly(styrene-butadiene) copolymer with 15% of available sites crosslinked

(c) Polyethylene having a density of 0.985 g/cm3 and a degree of polymerization of 2500; polyethylene having a density of 0.915 g/cm3 and a degree of polymerization of 2000