含抗氧剂的辐射交联LDPE的熔融与结晶行为

MELTING AND CRYSTALLIZATION OF LDPE CONTAINING ANTIOXIDANTS AND IRRADIATED

含有不同抗氧剂的ＬＤＰＥ在空气中、室温下经受２００ｋＧｙ的电子束辐照处理后，和未加抗氧剂的试样比较，凝胶分数下降６％一３０％。ＤＳＣ测定表明，辐照试样的熔点和熔融热焓、结晶温度与结晶热焓比未辐照试样略有降低。相同组成的试样两次升温和降温ＤＳＣ测定结果指出，熔点和结晶温度不变，但熔融和结晶热焓呈下降趋势。降温ＤＳＣ分析还发现，辐照不影响所研究的ＬＤＰＥ试样中支链分布的嵌段性质。试样经热处理后进行的Ｘ射线衍射分析表明，辐照未引起试样晶体结构和晶粒尺寸明显的变化，但辐照试样的结晶度略低于未辐照试样。

Gel fraction(%) of LDPE containing antioxidants and irradiated by fast electron beam(200 kGy) at ambient temperature and in air decreases by 6%--30% as compared with the control specimens. DSC measurement shows that the peak melting temperature Tm, enthalpy of fusion, peak crystallization temperature Tc and enthappy of crystallization of the irradiated LDPE are somewhat declined relative to that of unirradiated specimens. The second heating and cooling DSC run demonstrates that the Tm and Tc of all the samples studied in this work are not changed, but their enthalpies of fusion and crystallization tend to decrease, The cooling DSC reveals no influence of radiation on the blocky distribution of the branches in the LDPE used in this work. The X-ray diffraction analysis for the heat--treated samples demonstrates that irradiation does not cause appreciable change of the crystal structure and crystallite size of the samples, but the degree of the crystallinity of the irradiated samples is somewhat lower than that of unirradiated ones.