芳香族聚噁二唑纤维的酸老化行为及降解机理研究

Ageing behavior and degradation mechanism of aromatic polyoxadiazole fibers in acid

研究了芳香族聚-1,3,4-噁二唑(POD)纤维浸泡于不同酸溶液中的力学性能和表面形貌的变化,表征了酸老化前后POD纤维的聚集态结构与分子结构,探讨了POD纤维的酸老化机理。结果表明:POD纤维力学性能在体积分数30%的硫酸溶液中下降最快,在硝酸溶液中老化最严重;POD纤维老化后线密度变大,温度越高,力学性能下降越快;POD纤维经酸老化后纤维表面被破坏,有沟槽,纤维聚集态结构的有序性降低,纤维特性粘数下降;POD纤维的酸老化是酸催化下的水解过程,分子结构中噁二唑环被破坏,最终水解生成羰基化合物对苯二甲酸。

The mechanical properties and surface morphology of aromatic poly（ 1,3,4-oxadiazole） （POD） fiber were studied in different acid solution. The aggregation structure and molecular structure of POD fiber were characterized before and after acid ageing. The acid ageing mechanism of POD fiber was discussed. The results showed that the mechanical properties of POD fiber decreased fastest in 30% sulphuric acid solution by volume fraction and the aging behavior was most serious in nitric acid solu- tion. The linear density of POD fiber rose after ageing. The higher the temperature was, the faster the mechanical properties de- creased. The surface of POD fiber was damaged and some grooves appeared on the fiber surface after ageing. Moreover, the order of the aggregation structure and the intrisic viscosity of the fiber were decreased. The ageing behavior of POD fiber was a hydroly- sis process catalyzed by acid. The rings of oxadiazole were destroyed and hydrolyzed into carbonyl compounds, terephthalic acid.