交联聚乙烯绝缘料耐焦烧性能的对比研究

Comparative study on scorching resistance of cross-linked polyethylene insulating materials

选取3种牌号商用高压电缆交联聚乙烯绝缘料为研究对象,首先通过高温剪切作用下绝缘料熔体扭矩随温度的变化规律,对比分析3种绝缘料的耐焦烧性能,并通过凝胶含量表征焦烧试样的焦烧程度,然后提出采用绝缘料熔体在高温下的扭矩变化率作为特征量来表征绝缘料耐焦烧性能的方法,并通过不同牌号商用绝缘料焦烧程度的表征结果验证该方法的有效性。此外,通过红外光谱对3种绝缘料中交联剂含量和抗氧剂含量进行对比分析,结合凝胶渗透色谱法测得的绝缘料基料分子量,建立了绝缘料添加剂含量、基料分子量与其耐焦烧性能的关联。结果表明:通过绝缘料在高温剪切作用下的扭矩分析,可以有效区分不同商用绝缘料的耐焦烧性能,并发现交联剂含量过高是导致绝缘料耐焦烧性能差的主要原因,通过适当减少交联剂用量、增加抗氧剂用量、降低重均分子量可以提升绝缘料的耐焦烧性能。

Three brands of commercial cross-linked polyethylene insulating materials for high-voltage cables were selected as the research objects.At first,the scorching resistance of three insulating materials was compared and analyzed by the change rule of melt torque of insulating materials with temperature under the action of high temperature shearing,and the scorching degree of the scorched sample was characterized by the gel content.Then,the method of using the torque change rate of insulating material melt under high temperature as the characteristic quantity to characterize the scorching resistance of insulating material was proposed,and the effectiveness of this method was verified by characterizing the scorching degree of different brands of commercial insulating materials.In addition,the crosslinking agent content and antioxidant content in the three insulating materials were compared and analyzed by infrared spectrum,and the correlations between the additive content of insulating material,the molecular weight of base material,and its scorch resistance were established on the basis of molecular weight of insulating material base material measured by gel permeation chromatography.The results show that the scorching resistance of different commercial insulating materials can be effectively distinguished by the torque analysis on insulating materials under the action of high temperature shearing.It is found that the high content of crosslinking agent is the main reason for the poor scorching resistance of insulating materials,and the scorching resistance of insulating materials can be improved by appropriately reducing the crosslinking agent content,increasing the antioxidant content,and reducing the weight average molecular weight.