Banerjee Ritima, Ray Suprakas Sinha, Ghosh Anup K
Department of Materials Science & Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India.
DST-CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria 001, South Africa.
Polymers (Basel). 2018 Apr 4;10(4):400. doi: 10.3390/polym10040400.
The present work is a novel attempt to understand the microstructure of styrene-ethylene-butylene-styrene (SEBS)/polystyrene (PS) blends not only through morphological studies, but also thermal, mechanical and rheological characterizations. SEBS/PS blends containing 10, 30 and 50 wt % PS were processed in a micro-compounder and characterized. Scanning electron microscopy (SEM) studies, with selective staining of the PS phase, revealed the presence of PS as nanometer-sized domains, as well as phase-separated micrometer-sized aggregates. Blends with 30 and 50 wt % PS exhibited a fibrillar microstructure, obeying Hirsch's model of short fiber composites. A remarkable increase in glass transition temperature indicated a strong interaction of the fibrils with SEBS. All blends showed two modes of relaxation corresponding to the two phases. A single mode of relaxation of the PS phase has been attributed to combined effects of the partial miscibility of the added PS, along with the interaction of the fibrils with SEBS. The long relaxation time of the elastomeric phase indicated the tendency of these materials to undergo time-dependent shrinkage in secondary processing operations. An increase in PS content resulted in the lowering of the shear viscosity and energy requirement for mixing, indicating the ease of processing.
本研究是一次全新的尝试，旨在不仅通过形态学研究，还通过热学、力学和流变学表征来理解苯乙烯-乙烯-丁烯-苯乙烯（SEBS）/聚苯乙烯（PS）共混物的微观结构。含有10%、30%和50%（重量）PS的SEBS/PS共混物在微型混合机中进行加工并表征。通过对PS相进行选择性染色的扫描电子显微镜（SEM）研究表明，PS以纳米尺寸的区域以及相分离的微米尺寸聚集体形式存在。含有30%和50%（重量）PS的共混物呈现出纤维状微观结构，符合赫希短纤维复合材料模型。玻璃化转变温度显著升高表明纤维与SEBS之间存在强烈相互作用。所有共混物均表现出对应于两相的两种松弛模式。PS相的单一松弛模式归因于添加的PS的部分互溶性以及纤维与SEBS的相互作用的综合影响。弹性体相的长松弛时间表明这些材料在二次加工操作中存在随时间变化的收缩趋势。PS含量的增加导致剪切粘度降低以及混合所需能量减少，表明加工更容易。
