取向度对聚乙烯介电性能的影响

聚合物取向度对电气绝缘性能具有重要的影响。该文研究通过两种方法获得具有不同取向度的聚合物材料。在第一种方法中，通过在聚乙烯中加入5％～10％的乙烯．丙烯共聚物使在相同工艺条件下制备的共混物薄膜比纯聚乙烯薄膜具有更高的取向度。在第二种方法中，采用传统的拉伸方法使聚乙烯薄膜的取向度沿拉伸方向得到提高。研究中，多种方法被用于评价薄膜的取向程度，如热收缩率、偏光显微镜和测量声速法等。文中同时研究了具有不同取向度的聚合物薄膜的电气击穿强度，电流和空间电荷特性。分析了聚合物取向度与其电气性能之间的关系，并对其机理进行了探讨。

EFFECTS OF ORIENTATION ON ELECTRICAL PROPERTIES OF POLYETHYLENE

The electrical properties are strongly affected by the orientation of polymers. In this study, two kinds of methods were used to obtain low density polyethylene (LDPE) film specimens with different orientation. In the first method, LDPE was blended with random copolymer of ethylene and propylene (EP) with EP content of 5%-10%. The blend specimen has a stronger orientation than the pure LDPE specimen. In the second method, drawing method was used to enhance the orientation of LDPE film. The orientation of specimens had been characterized by some methods, such as thermal shrinkage, polarizing microscope and sound velocity. The film specimens with different orientation had been investigated on electrical breakdown strength, current and space charge behaviors. The relationship between orientation and electrical properties was discussed.