Structure of polybutadienes synthesized with a new catalyst system, 2 - Blends of trans- and cis-1,4-polybutadiene

摘要

The structure, composition and temperature behaviour of polybutadienes prepared wit binuclear metal complex catalysts immobilized on a solid carrier are investigated by differential scanning calorimetry, infra-red spectroscopy and X-ray scattering. Polybutadienes of nascent structure are blends of trans-1,4- and cis-1,4-homopolymers, whereas 1,2-units are randomly distributed in both macromolecules. The blends exhibit two-step melting characteristics for the crystalline trans-1,4-polybutadiene: the low-temperature transition from the monoclinic crystal form to the pseudohexagonal mesophase and the high-temperature transition From mesophase to the melt. A bimodal character of the endothermic maximum in DSC traces was observed for the former transition. fn addition, it was shown that the nascent blend treated by hot toluene posseses a three-phase structure and contains, besides the well-known trans-1,4-polybutadiene crystalline and amorphous phases, an additional phase component of unknown structure. [References: 15]