COCRYSTALLIZATION AND PHASE SEGREGATION OF POLYETHYLENE BLENDS .1. THERMAL AND VIBRATIONAL SPECTROSCOPIC STUDY BY UTILIZING THE DEUTERATION TECHNIQUE

Crystallization behavior has been investigated by DSC and Fourier transform infrared spectroscopic methods for the 50/50 wt % blends of deuterated high-density polyethylene (DHDPE) with hydrogeneous PE species having different branching content. A utilization of the fully deuterated sample as one component has made it possible to trace the crystallization behaviors of the H and D species separately by measuring the CH2 and CD2 vibrational bands as a function of temperature. The blend between DHDPE and linear low-density PE (LLDPE) with a relatively low degree of short-chain branching has been found to exhibit a cocrystallization phenomenon even in the slow cooling process from the melt. For the blend with high-density PE or LLDPE of a high degree of branching, the phase segregation has been observed between the D and H species. In this way the degree of cocrystallizability has been found to correlate with the branching content. The Davydov splitting of the infrared crystalline bands has also been found to be affected by the degree of branching of the H species in the blend.