Crystallization Behavior and Structure in Crystalline Block Copolymer and Its Blend with Crystalline Homopolymer

抄録

Crystallization behavior and structure in crystalline block copolymer and its blend with crystalline homopolymer were studied using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and small-angle light scattering (SALS). The crystalline block copolymer subjected to present work was polyethylene-block-poly (ethylene-alt-propylene), PE-PEP, which was used for crystalline block component of the crystalline homopolymer/crystalline block copolymer blend. Hydrogenated polybutadiene (HBD-2) was chosen as the crystalline homopolymer component of the blend. The HBD-2/PE-PEP (50/50 by weight) blend provided characteristic cocrystallization, which was confirmed by DSC, SAXS and SALS, resulting from the similar polyethylene-like segments in both components. In the blend, two crystallizable components cocrystallized into a single type of lamellar structures as revealed by single peak in DSC. The spherulites sizes and integrated intensities change during crystallization both obtained from SALS measurements supported cocrystallization. Both in block copolymer and the blend, multiple SAXS peaks suggested that microphase separation driven by crystallization took place in microscopic scale, whereas spherulites formation in macroscopic scale was also developed, which was confirmed by SALS results.