ETHYLENE AND STYRENE OR ALFA-METHYL STYRENE COPOLYMER WITH HOMOGENEOUS METALLOCENE CATALYST

摘要

Styrene and alfa-methyl-Styrene were employed in ethylene copolymerization with the homogeneous metallocene catalyst Et-(Flu)_2ZrCl_2/ MAO. It was observed that the catalyst activity has increased with the addition of very low amounts of comonomer in comparison with the homopolymerization of ethylene. The obtained polymers were characterized according to their melting temperature (T_m) and crystalline degree (X_c), through DSC analysis. The lowest melting temperature of the E-Sty copolymers obtained was 119°C, which correspond to 1.5 %molar of styrene in the polymer chain. On the other hand, the addition of increasing amount of alfa-methyl-styrene to ethylene polymerization has significantly increased the crystalline degree of the polymers, although have not changed their T_m, probably meaning that the substituted styrene has acted as chain transfer agent.