POLYETHYLENE GRAFT-COPOLYMERS WITH A LIQUID-CRYSTALLINE COMPONENT IN THE SIDE-CHAINS

An ethylene-vinyl acetate copolymer (EVA) was chemically modified by t he introduction of pendent thiol groups (EVA-SH) suitable for chain tr ansfer. The resulting copolymer was grafted with 4-phenylazophenyl 4-( 4-acryloyloxybuloxy)benzoate, a liquid crystalline monomer (LCM), init iated by AIBN. Grafting was performed at LCM/EVA-SH mass ratios of 10, 5, 2 and 1 in the feed. The grafting degree, i.e., the fraction of LC polymer in the graft copolymer, ranged from ca. 5-30 wt.-%. The therm al transitions were investigated by DSC, pointing at marked microphase separation between LC and polyethylene moieties. The anisotropic prop erties of the graft copolymers were confirmed by cross-polarized light microscopy. All the samples showed birefringence at 140 degrees C, so me only on shearing however.