Studies of structural composition distribution heterogeneity in ethylene/1-hexene copolymers using thermal fractionation technique (SSA) - Effect of catalyst structure

Investigations into the compositional heterogeneity of ethylene/1-hexene copolymers obtained with various zirconocene/MAO catalysts, either homogeneous or supported on inorganic carriers such as a complex of magnesium chloride with tetrahydrofuran or methyl alcohol, were conducted. The dependence between metallocene structure, as well as catalyst immobilization, and the compositional heterogeneity of the related products was investigated. It was found that the heterogeneity of copolymers is determined by the metallocene catalyst structure. The amount of peaks on the DSC thermograms of copolymers and their division increase with the increase of bulkiness of the ligand in the catalytic system. The immobilization of the investigated catalysts on the magnesium carrier leads to an increase of the copolymer's compositional heterogeneity. However, the modification of the MgCl2 carrier by tetrahydrofuran or methyl alcohol seems to not have any influence on the copolymers' CCD. (c) 2005 Elsevier B.V. All rights reserved.