Effect of the catalyst on the copolymers of styrene with methyl methacrylate by Ziegler–Natta polymerization

The copolymerization of styrene with methyl methacrylate by the Ziegler–Natta catalysts, Pr(OCOCCl3)3/AlEt3 (System I) and Co(acac)3/AlEt3 (System II), has been carried out. The kinetic behaviour of the copolymerizations is described. The catalytic activities were found to be maximum at Al/Pr ratio of 12 and Al/Co ratio of 2.5. The activation energies were found to be 59.57 and 27.66 kJ mol−1 for the two systems. Molecular weights of the polymer were 2.42×106 and 2.00×105. A free radical mechanism is proposed. Copolymers were characterized by IR, 1H NMR and 13C NMR techniques. Reactivity ratios were determined by Kelen–Tudos method.