The heat-resisting polyamide polyphthalamide(PPA) samples with different antioxidants and titanium dioxide were prepared by extrusion blending.The changes in yellow index(YI) and Blu-ray brightness(R457) of these samples were investigated.The effect of adding ultramarine to cover yellow for PPA was studied.The structural change in the thermal oxidation was analyzed by means of FTIR-ATR.The influence of adding different antioxidants to PPA was analyzed by thermogravimetry.The results show that adding antioxidants and titanium dioxide can improve the whiteness of PPA.The antioxidants H3373 and titanium dioxide R104 have synergistic effect for improving the whiteness.Adding ultramarine is possible to reduce the YI of PPA.PPA has slight heat ageing decomposition within the scope of processing temperature.The antioxidant effect is as follows:H 10＞KBG779＞H3373.Infrared analysis shows that PPA yellowing phenomenon is caused by carboxyl,aldehyde group or ketone and other chromophores which appears in heat ageing decomposition of PPA.%通过挤出共混工艺制备了添加不同抗氧剂和钛白粉的聚邻苯二甲酰胺(PPA)高温尼龙样品,研究了热氧老化前后样品黄色指数(YI)、蓝光白度(R457)的变化情况；考察了微量群青对PPA热老化后的遮黄作用.通过傅立叶红外光谱分析了PPA热氧化前后的结构变化；并通过热重曲线分析了几种抗氧剂对PPA热氧化降解的影响.结果表明,添加抗氧剂、钛白粉能很好地提高PPA产品的R457,其中抗氧剂H3373在与钛白粉R104配合使用时有很好的协同作用；添加微量群青能够降低PPA的YI；PPA在加工温度范围内会发生轻微的热老化分解,抗氧剂的抗氧化效果为H10＞KBG779＞H3373；红外分析表明,PPA的黄变现象是由于PPA热氧化生成羧基、醛基或酮等生色基团引起的.
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