含添加剂的等规聚丙烯的辐射诱发自由基转化和辐射交联效应

由ESR方法观察到等规聚丙烯(PP)γ辐射诱发自由基向多烯自由基的转化时间?6天,而6.8％APP和7.6％EPP(APP、EPP分别表示含十六烷、十六烯-1的PP)的转化时间>10天。本实验还观察到这两种添加剂均抑制PP的辐射交联,其中十六烯-1的效果更为显著,测得PP、6.8％APP、4.0％EPP和7.6％EPP的起始凝胶剂量分别为12.6、20.7、30.5和>108 Mrad。本文认为,十六烯-1的烯丙位氢原子易于失去,因而较十六烷更大程度地降低聚丙烯自由基产额和辐射交联。然而,对添加剂影响自由基转化的机制还需进一步研究。

RADICAI CONVERSION AND CROSSLINKING EFFECTS IN GAMMA IRRADIATED ISOTACTIC POLYPROPYLENE WITH SOME ADDITIVES

The period of conversion from alkyl radicals to polyengl radicalsin gamma-irradiated isotactic polypropylene (i.e. PP) is ? 6 days: while in 6.8%APP and 7.6% EPP (APP and EPP are PP containig hexadecane and hexadecene-1,respectively), It was found to be more than 10 days. It was also measured that theinitial gelation dose of PP, 6.8% APP, 4.0% EPP and 7.6%EPP are 12.6, 20.7,30.5 and>108 Mrad, respectively. This indicates that both of the additives inhibit theradiation crosslinking of PP, and hexadecene-1 shows a stronger effect than hexadecane.It was assumed that hexadecene-1 offers its active allyl H atoms to reduce the radicalyield of PP, and then inhibit the radiation crosslinking of PP more strongly than he-xadecane. However, the whole mechanism related to the effect of the additives on PPradical connversion needs further research.