聚丙烯/聚烯烃弹性体复合材料物理机械性能及交流电性能

AC performance and physical/mechanical properties of polypropylene/polyolefin elastomers blends

聚丙烯(PP)分别与乙烯-辛烯共聚物(POE)弹性体、苯乙烯-乙烯/丁烯-苯乙烯三嵌段共聚物(SEBS)熔融共混,制备出不同质量分数的弹性体/PP复合材料。SEM结果表明复合材料微观形貌呈现弹性体均匀分布在PP中构成的"海岛结构",随着复合体系中弹性体含量的增加,岛相浓度与尺寸均增大。DSC结果表明当弹性体含量增加时,复合材料结晶度略有下降。力学测试结果表明165℃下复合材料的热延伸形变量均大于PP的热延伸形变量,且随弹性体含量增加复合材料热延伸形变量逐渐增加。DMA测试结果表明30%质量分数的POE/PP复合材料的25℃弹性模量降低至约750 MPa。交流介电强度测试结果表明不同温度下复合材料交流介电强度均小于PP,其中25%质量分数的SEBS/PP复合材料交流介电强度最接近PP。弹性体/PP复合材料中的"海岛结构"既保留了PP较高温度下的机械强度,又明显降低了PP材料的硬度,增加了韧性和柔顺性。

Polypropylene/elastomer blend materials with different content( 20%,25%,30%) of elastomer are prepared by blending polypropylene and ethylene/octene copolymer elastomers( POE),polypropylene and styrene-ethylene/butylene-styrene triblock copolymer( SEBS). The properties of the blends were tested by SEM,polarizing microscope test,DSC,mechanical performance,DMA,and breakdown performance to investigate the micromorphology and crystallization properties,AC breakdown strength and mechanical properties of PP and blends. The results of SEM showed that the elastomer distributed evenly in PP,and formed"island structure". With the content of elastomer increasing,the concentration and size of island phase increased too. In the same composition,the island phase size of the SEBS/PP composite material is significantly smaller than that of the POE/PP composite material. The results of DSC showed that when the content of elastomer increased,the crystallinity of composite material decreased slightly,but the crystallization temperature( Tc) and crystalline melt temperature( Tm) did not change significantly.Tensile mechanical test results showed that the thermal extension deformation quantity of composite under165 ℃ were greater than PP,with the content of elastomer increasing,the result increased too. When the content of POE is 30 wt%,the deformation quantity rose to 11%,the tensile yield stress of 30 wt% SEBS composites decreased to 20. 01 MPa. DMA test results show that the elastic modulus decreased to about750 MPa with the component of 30 wt% POE at 25 ℃ . Breakdown strength of the composites is generally lower than that of PP,but the composite with 25 wt% SEBS almost keeps the breakdown performance of pure PP. The "island structure"in PP/elastomer blends retains the mechanical strength of PP,reduces the hardness of material significantly and increases the toughness and flexibility of PP at the same time.