Consider the following two polymeric systems:

A. Poly(styrene-butadiene) amorphous copolymer having a number-average molecular weight of 50,000 g/mol, and 8% of the available sites crosslinked.
B. Poly(styrene-butadiene) amorphous copolymer having a number-average molecular weight of 200,000 g/mol, and 20% of the available sites crosslinked. Respond to the following questions and justify your answer.

a. Which polymer will display the highest stiffness? Why?
b. Which polymer will display the highest tensile strength? Why?
c. Consider that polymer A has a value of Tg equal to – 25°C (-13F). Sketch two separate stress-strain profile for the same polymer A tested at -100°C (-148F) and 25°C. What is the difference? Explain and draw the graphs.