抗氧剂含量对交联聚乙烯热氧老化性能的影响

Influence of Antioxidant Content on Thermal Oxidation Resistance of Crosslinked Polyethylene

将受阻酚类抗氧剂4,4’-硫代双(6-叔丁基间甲酚)与低密度聚乙烯(LDPE)、交联剂DCP(过氧化二异丙苯)进行熔融共混,制备了一系列不同抗氧剂含量的交联聚乙烯(XLPE)。研究了抗氧剂含量对XLPE交联过程、凝胶含量、氧化诱导期(OIT)、热老化前后力学性能及热延伸特性的影响。研究结果表明,添加抗氧剂可以延迟交联反应,降低XLPE的交联度,提高材料的氧化诱导期及热老化后的拉伸强度,使材料的热延伸性能增加。与无抗氧剂的样品相比,当抗氧剂含量为0.3%时,XLPE起始交联反应温度从155.2℃延迟至160.3℃,OIT由2 min延长至40 min;当抗氧剂含量从0增加到0.8%时,XLPE交联度由90%降至76.4%;热延伸伸长率由40%增大至131%。

A series of crosslinked polyethylene(XLPE)with different antioxidant contents were prepared by melt blending from hindered phenol antioxidant 4,4’-thio-bis(6-tert-butyl-m-cresol),low density polyethylene(LDPE)and crosslinking agent DCP(dicumenyl peroxide).The effect of antioxidant content on crosslinking process,gel content,the oxidation induction time(OIT),mechanical properties before and after thermal ageing,and thermal elongation of XLPE samples were studied.The results indicated that initial crosslinking temperature was delayed after adding antioxidant and gel content of XLPE samples was found to be decreasing with the increase in antioxidant content.The OIT of XLPE sample and the tensile strength of XLPE sample after thermal ageing were increased with the increase in antioxidant content.The increase in thermal elongation of XLPE samples was also observed with increase in antioxidant content.Compared to that of sample without antioxidant,the initial crosslinking temperature of XLPE sample with 0.3%antioxidant was delayed from 155.2℃to 160.3℃and the OIT of sample was prolonged from 2 min to 40 min.With the increasing antioxidant content from 0 to 0.8%,the gel content of XLPE samples was dramatically reduced from 90%to 76.4%and the thermal elongation was obviously increased from 40%to 131%.