中文摘要：

研究了注射成型尼龙6/苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物（PA6/SEBS）体系中微结构形态,SEBS含量,PA6结晶取向对线膨胀系数（CLTE）的影响.研究表明,当SEBS含量超过20wt%,PA6/SEBS注射成型体系形成层状共连续结构时,可以明显地降低流动方向的热膨胀系数.TEM和WAXD分析表明,该层状共连续结构中不仅SEBS微层取向,而且大多数PA6片晶垂直于SEBS微层生长,其中晶胞b轴（PA6分子链）倾向于沿流动方向取向.程序升温WAXD研究表明,PA6/SEBS（60/40）体系中各晶轴的线膨胀系数差别很大,其中晶胞b轴为-5.8×10^-5K^-1.具有负膨胀系数的晶胞b轴沿着流动方向取向可能是除层状共连续结构效应以外导致材料低膨胀化的第二种驱动力.

英文摘要：

Rubber was used as an additive instead of an inorganic filler to mediate the thermal expansion behavior of plastics.This is based on the fine control of the micro-structure so that the expansion is preferentially along the thickness direction.Reactive extrusion and injection molding processes were employed for deformation of the rubber domains into microlayers.It is found that when the rubber domains are deformed into microlayers and co-continuous with the plastic matrix,the coefficient of linear thermal expansion（CLTE）in directions parallel to the microlayers decreases to a very low value.The relationship between the content of styrene/ethylene-butylene/styrene block copolymer（SEBS）,the crystallization behavior of polyamide 6（PA6）and CLTE for injection-molded PA6/SEBS blends was investigated.It was found that when the content of SEBS phases exceeded 20 wt%,the CLTE of PA6/SEBS in flow direction decreased drastically.TEM observation showed that both the plastic and rubber phases were elongated and orientated along flow direction（FD）,and PA6 crystals were mostly oriented normal to the SEBS layers.WAXD measurements demonstrated that b-axis of PA6 unit cells preferred to orientation along FD based on the calculations of the degree of orientation for PA6 crystallographic axes,and the CLTE of PA6 lattice was determined to be 7.0×10^-5 K^-1,-5.8×10^-5 K^-1,and 25.8×10^-5 K^-1 for a,b,and c-axes,respectively,for the injection-molded PA6/SEBS（60/40）.Since the b-axis has thermal retraction effect,the orientation of b-axis along FD might provide the second driving force to reduce the CLTE of injection-molded PA6/SEBS.