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采用高温干燥箱在230、250、275、300℃下制备了不同老化状态的芳纶Ⅲ样品,并对老化试样进行了单丝拉伸测试及相应的结构分析。结果表明,在实验温度范围内,芳纶Ⅲ的强度保留率随热氧老化时间的延长和温度的升高而降低;TG和IR分析表明,芳纶Ⅲ的化学结构未随热氧老化处理而发生明显改变;通过X射线衍射分析,发现纤维聚集态结构随温度升高发生重排;SEM测试表明,经过热氧老化纤维的断裂方式从劈裂断裂变成了脆性断裂;最后,结合纤维聚集态结构模型,解释了老化前后纤维力学性能下降的原因及原纤劈裂到脆性断裂的机理。
Aramid samples with different aging conditions were prepared at 230, 250, 275 and 300 ℃ by high temperature drying oven. The monolayer tensile test and structural analysis of the aged samples were carried out. The results show that the strength retention rate of aramid Ⅲ decreases with the extension of the aging time and the increase of the temperature in the range of experimental temperature. The TG and IR analyzes show that the chemical structure of aramid Ⅲ does not change with the aging process X-ray diffraction analysis showed that the fiber aggregated state rearranged with increasing temperature. The SEM test showed that the fracture mode of thermal aging fiber changed from cleaving to brittle fracture. Finally, State structure model to explain the reasons for the decline of mechanical properties of fiber before and after aging and fibril splitting to brittle fracture mechanism.