PAN基碳纤维制备过程中热处理时间对结构影响的研究

热处理时间是碳纤维制备过程中的一个重要参数,实际生产中,无法实现单纯改变某一温度点的处理时间,调整运行速度会使得整个过程中每个温度点的热处理时间都会随之变化,最终性能是各个温度点共同作用的结果。通过DSC、FTIR、XRD、Raman、元素分析等测试手段分析了热处理时间延长对各阶段结构和最终性能的影响。实验结果表明:热处理时间延长会大大提高低温热处理阶段的热处理程度,均质性更好,此阶段环化反应等特征反应进行的更为充分;经900℃处理后乱层石墨微晶开始初步形成,热处理时间延长有利于形成更大的石墨片层,在此基础上进行1 400℃处理,得到的最终碳纤维样品中,热处理时间越长其石墨化度越高、石墨片层间距越大、片层大和堆叠厚度低,直接导致了样品模量的提高。

Study of effect of heat treating time on the structure in the preparation process of PAN-based carbon fiber

The heat treatment time is an important parameter in the preparation of carbon fiber. Changing the heat treating time of one temperature point can not be achieved in actual production. Each temperature heat treating time in the whole process will change with adjusting the speed of process. The final performance is depended on each temperature point. With DSC, FTIR, XRD, Raman and elementary analysis etc. test means, through the experimental, the impact of prolonging heat treating time on the structure and final properties of the various stages. The results show that： redoubling the heat treatment time will gradually improve the degree of the low-temperature heat treatment, more homogeneity; characteristics reaction such as the cyclization reaction will be more fully. Turbostratic graphite crystallites initially formed at 900 ~C, redoubling the heat treatment time is benefit to the formation of bigger graphite layers. After heat treatment at 1 400 ℃, there are impacts on graphite crystallites of carbon fiber by redoubling the heat treatment time, the specific performance of that are prolonging treating time makes d002 of graphite crystallites larger, Lc smaller, La increases.