COPOLYMERIZATION OF PROPENE WITH ETHENE BY ET(IND)(2)HFCL2 METHYLALUMINOXANE CATALYST/

Propene/ethene copolymerizations with a Et(Ind)(2)HfCl2/methylaluminox ane catalyst system were performed in toluene at 40 degrees C and 60 d egrees C using a semi-how method. Sequence analysis data and the react ivity ratios r(P)r(E) Obtained for the product from C-13-NMR measurem ents indicated the formation of short ethene blocks in the chain. Addi tion 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 temperatur e of the polymer. With 46 mol.% ethene in the polymer an almost amorph ous copolymer was produced. Dynamic mechanical analysis (DMA) showed a strong decrease in the stiffness values as a function of increasing e thene in the copolymer. Higher ethene incorporations gave damping curv e maxima at lower temperatures, indicating that higher concentrations of ethene produce copolymers with higher impact strength. (C) 1998 Els evier Science Ltd. All rights reserved.