张力拉伸对PAN纤维热稳定化反应进程的影响

在不同拉伸条件下,对聚丙烯腈(PAN)纤维进行热处理。借助傅里叶变换红外光谱、X射线衍射等表征手段,研究了PAN纤维热稳定化过程中,拉伸张力对纤维分子链聚集态结构及化学反应的影响。结果表明:PAN纤维热处理过程中,施加张力会在一定程度上影响纤维的环化反应。当热处理温度较低(180℃)时,施加张力可抑制环化反应的发生;热处理温度较高(大于200℃)时,拉伸张力有利于环化反应的发生。热处理过程中,施加张力,对PAN纤维结晶度影响较小,晶区取向和全取向度增加,晶粒尺寸增大。这是由于拉伸与温度双重作用影响了纤维的聚集态结构,导致参与环化反应的分子数量发生变化。

Effect of drawing under tension on thermal stabilization process of PAN fiber

Polyacrylonitrile(PAN) fiber was exposed to heat treatment under different drawing conditions.The effect of the drawing tension on the aggregation structure of PAN fiber molecular chain and chemical reaction was studied during thermal stabilization process by Fourier transform infrared spectrometry and X-ray diffraction.The results showed that the tension on the PAN fiber affected the cyclization reaction in some degree during the thermal stabilization.The tension on the PAN fiber inhibited the cyclization reaction at relatively low heating temperature(180 ℃),but accelerated the cyclization reaction at higher heating temperature(above 200 ℃).The tension affected the crystallinity of PAN fiber little,improved the crystalline orientation and full orientation degree and increased the crystal size during the thermal stabilization.This was attributed to the double effect of drawing and temperature on the aggregation structure of the fiber,which resulted in the change of molecule amount paticipating the cyclization reaction.