The degradation rate of a polymer mixture depends on the particular polymer mixture, and the presence of a second polymer can increase, decrease, or not affect the degradation rate of the first polymer. The degradation rates of poly(vinyl acetate) in both the presence and absence of polystyrene at various temperatures (220-250°C) were experimentally determined. The molecular weight distributions of the polymers were obtained by analyzing the samples by gel permeation chromatography. Continuous distribution kinetics were employed for determining the degradation rates of binary polymer mixtures. The results indicated that, because of the interaction of mixed radicals with polymer by hydrogen abstraction, the degradation rates of poly(vinyl acetate) are considerably enhanced in the presence of polystyrene, while the degradation rate of polystyrene decreases.