Abstract
Uncured blends of high cis-polybutadiene rubber and styrene-butadiene-styrene block copolymer (styrene content: ca. 25%), prepared by mill blend, were studied.
And it was found that this blend system is a microheterogeneous one and crystallization of high cis- polybutadiene rubber is observed at low temperature. But, as compared with the case of polybutadiene rubbergeneral purpose polystyrene resin blend, a mutual interaction between high cis-polybutadiene rubber and styrene-butadiene-styrene block copolymer is strong and zone sizes of dispersed polymers are small.
Different from a microheterogeneous polybutadiene rubber-general purpose polystyrene resin blend system, the curves of blend ratio dependence of compression modulus at room temperature (in logarithm) were not “S” or “reversed S” shaped and were deviated much from a theoretical curve calculated from the mechanical model of a simple two phase blend system. According to a microscopic observation, in case of the blend with 50% styrene-butadiene-styrene block copolymer content changes of mixing state during remilling (roll surface temperature: 60°C) seem to exist, but the resultant softening phenomenon was not clearly observed. And further, it was deduced that the morphological characteristics of this blend system and the mutual interaction between blend polymers might be responsible for this phenomenon.
