Thermal behavior and structural features of propene/1-pentene copolymers by metallocene catalysts

Two families of propene/1-pentene copolymers prepared with different isospecific metallocene catalysts, rac-Et(Ind)2ZrCl2 and rac-Me2Si(2-MeBenz-[e]Ind)2ZrCl2, containing increasing amounts of 1-pentene were studied by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The thermal behavior of the copolymers was correlated with their microstructural features and a relationship between melting temperatures and average length of the isotactic sequences was established. Furthermore, the influence of the comonomer on the degree and type of crystallinity of the copolymers was investigated. Preliminary WAXD results demonstrate that only the ?-modification is present when crystallization takes place under fast cooling conditions, both in crystallized samples as well as in samples that had been aged for several weeks at room temperature.