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-Nat ta 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 ra tio 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 po lymer were 2.42 x 10(6) and 2.00 x 10(5). A free radical mechanism is propo sed. Copolymers were characterized by IR, H-1 NMR and C-13 NMR techniques. Reactivity ratios were determined by Kelen-Tudos method. (C) 2001 Elsevier Science Ltd. All rights reserved.