THERMAL AND MORPHOLOGICAL CHARACTERIZATION OF BINARY BLENDS OF FRACTIONS OF 1-OCTENE LLDPE

An ethylene/1-octene linear low-density polyethylene (LLDPE B) has been fractionated with respect to the short-chain branching content of the molecules, using the preparative temperature-rising elution fractionation (PTREF) technique. The LLDPE B studied, which is characterized by a high degree of heterogeneity on the level of the molecular weight and the comonomer content, was fractionated into six fractions having a more homogeneous intermolecular comonomer distribution. As a result of the differences in the chain microstructure of the fractions, a strong change in the thermal characteristics such as onset temperature of crystallization from the melt and melting temperature has been found. The morphology of the fractions, i.e., spherulitic texture and semicrystalline lamellar ordering, also strongly depends on the chain microstructure. In an attempt to elucidate the mutual influence of molecules having a different chain microstructure, as occurring within the unfractionated copolymer, blends of preparative TREF fractions were prepared and investigated with respect to their thermal behavior and morphology.