STRUCTURE AND PROPERTIES OF ETHYLENE/ALPHA-OLEFIN COPOLYMERS POLYMERIZED WITH HOMOGENEOUS AND HETEROGENEOUS CATALYSTS

Structure and properties of various ethylene / alpha-olefincopolymers were comparatively investigated. Copolymers polymerized with a heterogeneous Ziegler-Natta catalyst showed a wide intermolecular structural distribution, contrary to a narrow distribution of the copolymers obtained with a homogeneous catalyst system. This structural distribution was found to be correspondingly reflected in the distribution on a crystalline level such as a lamella thickness distribution (LTD). Mechanical properties of the copolymers were strongly influenced by the structural distribution; i.e., the narrower the chemical composition distribution and LTD, the stronger the impact strength. This result could be explained from the viewpoints of tie molecular concentration and its orientational homogeniety with deformation.