The ceiling temperature constraint encountered in the homopolymerization of alphamethylstyrene, AMS, can be circumvented by copolymerization with acrylonitrile to prepare multicomponent random microstructures that offer higher heat resistance than SAN. The feasibility of a thermal initiation of free radical chain polymerization is evaluated by the study of the terpolymerization kinetics of AMS-AN-Styrene. Process considerations such as polyrates, molecular weight of the copolymer formed, sensitivity of molecular weight, molecular weight distribution and kinetics to temperature are measured. The range of weight fractions of monomers of styrene, acrylonitrile and alphamethylstyrene varied in the study are f(sty) = 0.1-0.45, f(an) = 0.1-0.4, f(ams) = 0.2-0.75, respectively. Empirical correlations are provided for the polyrate, weight average molecular weight, M-w, in the temperature range 398-418 K.