采用热氧老化方法,研究了改性聚芳(噁)二唑纤维在200、250和300℃条件下的热氧老化趋势,并同间位芳纶和聚酰亚胺纤维进行了对比.结果表明:在200℃条件下经过80 d的热氧老化,改性聚芳(噁)二唑纤维的断裂强度保留率接近90％,在250℃条件下经过65 d的热氧老化,其断裂强度保留率在60％以上,在300℃条件下经过25 d的热氧老化,其断裂强度保留率依然大于70％；对改性聚芳(噁)二唑纤维在高温热氧老化后的线密度测试结果表明,线密度没有明显变化,纤维在200、250和300℃时尺寸变化较小.%The thermal oxidizing aging properties of modified aromatic polyoxadiazoles fiber at 200℃, 250℃ and 300℃ were studied by the thermal oxidizing aging method, and then its thermal oxidizing aging properties were compared with those of m-aramid fiber and polyimide fiber. The results showed that the breaking strength retention of the modified aromatic polyoxadiazole fiber after thermal oxidizing aging for 80 days at 200℃ is near 90% , over 60% after 65 days at 250℃, and higher than 70% after 25 days at 300℃ , respectively. The results also indicated that the linear density of the modified aromatic polyoxadiazole fiber after thermal oxidizing aging does not change obviously, which indicates that its dimension varies little at 200,250 and 300℃.
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