Terephthaloyl chloride and p-phenylene diamine are reacted to prepare poly(p-phenylene terepthalamide, Kevlar). Draw the structures of the monomers and the polymer repeat unit. Calculate the stoichiometric imbalance, r, needed to prepare a polymer with Mw = 20,000 and amine endgroups. Assume p = 0.99. Calculate the mass feed ratio of the two monomers to achieve this imbalance. Recalculate the mass feed ratio, if aniline is to be added to a stoichiometric mixture of the acid chloride and diamine, to achieve the same polymer but with phenyl endgroups.