Copolymerization of propylene with higher, linear α-olefins
Propylene was copolymerized with the linear α-olefins 1-octene, 1-decene, 1-tetradecene, and 1-octadecene. The metallocene catalyst Me2Si(2-Me-Benz[e]Ind)2ZrCl2, in conjunction with methylalumoxane as a cocatalyst, was used to synthesize the copolymers. The copolymers were characterized by 13C and 1H NMR with a solvent mixture of 1,2,4-trichlorobenzene (TCB) and benzene-d6 (9/1) at 100 °C. Thermal analyses were carried out to determine the melting and crystallization temperatures, whereas the molecular weights and molecular weight distributions were determined by gel permeation chromatography with TCB at 140 °C. Glass-transition temperatures were determined with dynamic mechanical analysis. Relationships among the comonomer type and amount of incorporation and the melting/crystallization temperatures, glass-transition temperature, crystallinity, and molecular weight were established. Moreover, up to 3.5% of the comonomer was incorporated, and there was a decrease in the molecular weight with increased comonomer content. Also, the melting and crystallization temperatures decreased as the comonomer content increased, but this relationship was independent of the comonomer type. In contrast, the values for the glass-transition temperature also decreased with increased comonomer content, but the extent of the decrease was dependent on the comonomer type.