Riitta Djupfors, P. Starck, B. Löfgren
Jul 1, 1998
Citations
0
Influential Citations
5
Citations
Journal
European Polymer Journal
Abstract
Abstract Propene/ethene copolymerizations with a Et(Ind) 2 HfCl 2 /methylaluminoxane catalyst system were performed in toluene at 40°C and 60°C using a semi-flow method. Sequence analysis data and the reactivity ratios r P * r E obtained for the product from 13 C-NMR measurements indicated the formation of short ethene blocks in the chain. Addition of ethene to the copolymer caused an activation effect, which was very strong for small amounts. Addition of ethene also increased the molar mass, but decreased the crystallinity and the melting temperature of the polymer. With 46 mol.% ethene in the polymer an almost amorphous copolymer was produced. Dynamic mechanical analysis (DMA) showed a strong decrease in the stiffness values as a function of increasing ethene in the copolymer. Higher ethene incorporations gave damping curve maxima at lower temperatures, indicating that higher concentrations of ethene produce copolymers with higher impact strength.