AbstractThe formation of styrene‐maleic anhydride‐methyl methacrylate terpolymers was studied in batch polymerization process. The process of polymerization was investigated in quasi‐steady‐state time periods by the Markov statistics. The results of the calculations for high conversions were compared with the experimental results. Based on the advantage of the method, PVC blends were produced which (with 40% of blend component) increased the Vicat‐A and Vicat‐B heat‐resistance of PVC by 40–43°C and 18–