预氧化程度对聚丙烯腈预氧化纤维结构与性能的影响

Effect of pre-oxidation degree on structure and properties of polyacrylonitrile thermal oxidative stabilized fiber

通过在空气气氛下恒定牵伸PAN纤维,制备具有不同预氧化程度的预氧化纤维(基于傅里叶变换红外光谱用相对环化率表征预氧化程度),探究预氧化程度对预氧化纤维的化学结构、晶体结构、微观结构和力学性能的影响。结果表明,预氧化程度高于54.7%时,共轭羰基出现且含量逐渐增大;预氧化程度为83.2%时,纤维形成新的漫散射峰和序态结构,纤维横截面具有明显的径向不均匀结构现象,断裂伸长率较小;预氧化程度约为72.0%时,可以获得结构缺陷少,力学性能较为良好的预氧化纤维。

Thermal oxidative stabilized(TOS)fibers with different pre-oxidation degrees were prepared by using constant draft polyacrylonitrile(PAN)fibers under air atmosphere according to the pre-oxidation degree obtained from the relative cyclization rate determined by Fourier-transform infrared spectroscopy.The effect of pre-oxidation degree on the chemical and crystal structures,microstructure,and mechanical properties of the resultant TOS fibers were investigated.The results indicated that the conjugated carbonyl groups began to form at a pre-oxidation degree greater than 54.7% and tended to increase gradually.The TOS fibers exhibited new diffuse peaks and ordered structures at a pre-oxidation degree of 83.2%,and their cross section presented an obvious radial non-uniform structure,so-called“skin-core structure”along with a decrease in the elongation at break.Therefore,the TOS fibers obtained a cyclization degree of 72%,thus resulting in fewer structural defects and better performance.