芳纶热拉伸处理过程对氢键影响的研究

研究了热处理过程对聚对苯二甲酰对苯二胺(PPTA)结构与性能的影响。通过对PPTA纤维升温红外光谱分析可以看出:在较低的热处理温度下,随着温度的升高,发现在3 300 cm^-1处—NH—伸缩振动峰向高波数方向移动,峰型变宽,吸收峰强度减弱。采用傅里叶变换红外光谱仪和单丝强度仪、比浓对数黏度等研究发现:经热拉伸处理后的PPTA纤维内部分子间氢键作用力增加,自由氢键数减少,游离的—NH_2含量却增加,纤维比浓对数黏度和强度降低,说明纤维的拉伸强度是由分子间作用力以及分子链段的长度共同作用的。

Analysis on Heat Treatment Temperature Effect on the Hydrogen Bonds of Aramid Fiber

The effect of the heat treatment process on the structure and mechanical properties of PPTA fiber are studied. According to the infrared spectroscopy analysis of PPTA fiber, it can be seen that at the lower heat treatment temperature, as the temperature increases, the —NH—moves towards the high wave number, the peak shape becomes wider, and the absorption peak intensity weakenes. Through Fourier transform infrared spectroscopy, monofilament intensity meter and inherent viscosity analysis, it is found that the internal intermolecular hydrogen bonding force of PPTA fiber after hot stretching treatment increases, the number of free hydrogen bonds decreases and the free —NH_2 content increases. The inherent viscosity and strength of the fiber are reduced, indicating that the tensile strength of the fiber is caused by the intermolecular force and the length of the molecular chain break.