不同改性聚丙烯电缆绝缘料的结构与性能对比分析

Comparative analysis of atructure and properties of different modified polypropylene cable insulation materials

聚丙烯(PP)是一种环保型电缆绝缘料,具有较为良好的绝缘性能,且作为热塑性材料具有可回收等优点。但PP的韧性差,在低温下容易发生脆断,因此需要对其进行增韧改性。文中在PP中分别添加10%质量分数的乙烯-辛烯共聚弹性体(POE)和氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)弹性体制备共混改性试样,以PP为基体与乙烯(PE)在反应釜内合成共聚改性试样,并测试改性前后PP的结构、理化性能、机械性能和电气性能,发现改性后PP韧性、拉伸强度和断裂伸长率均提高,但熔融温度下降,介质损耗增加。对比2种改性PP可得,共聚改性PP起始熔融温度更高,在20~80℃下的交流击穿场强更高;共混改性PP的机械性能更优异,高温下的介质损耗更低。综合考虑,共聚改性方式可能更适用于对PP的增韧改性。

Polypropylene(PP)is an environmentally friendly cable insulation material with relatively great insulation properties and has the advantages of being recyclable as a thermoplastic material.PP is easy to brittle fracture due to its poor toughness at low temperatures.Hence,it is necessary to improve the toughness of PP.In this paper,three modified PP samples are studied,namely PP blended with 10% mass fraction of polyolefin elastomer(POE),PP blended with 10% mass fraction of styrene ethylene butylene styrene(SEBS),and copolymerization modified PP specimen synthesized with PP as matrix and polyethylene(PE)in the reactor.The PP samples before and after modification are tested to obtain their physical properties,chemical properties,mechanical properties and electrical properties.It is concluded that the toughness,tensile strength and elongation at break of PP increase after the modification,while the melting temperature decreases and the dielectric loss increases.For the modification methods,the initial melting temperature and AC breakdown field strength at 20-80℃ of the copolymerization modified PP specimen are higher than those of the blending modified PP specimens.Instead,the blending modified PP specimens have better mechanical properties and lower dielectric loss at high temperature than the copolymerization modified PP specimen does.After comprehensive consideration,the copolymerization modification may be more suitable to enhance the toughness of PP than the blending modification.