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通过在线监测聚丙烯腈(PAN)纤维的热收缩应变和应力,研究了硼酸改性对PAN纤维预氧化的影响。试验结果表明:随着硼酸溶液浓度的增加,PAN纤维化学反应的起始和结束温度向高温方向移动,化学收缩量降低,预氧化纤维体密度逐渐降低,硼酸对PAN纤维化学反应有抑制作用;硼酸对分子内环化和分子间交联反应的抑制可有助于预氧化纤维均质化程度的提高,并可防止PAN纤维表面在较高温度下被过度氧化。
The effects of boric acid modification on PAN fiber preoxidation were investigated by online monitoring of the thermal shrinkage strain and stress of polyacrylonitrile (PAN) fibers. The experimental results show that as the concentration of boric acid solution increases, the onset and end temperatures of the chemical reaction of PAN fiber shift to high temperature, the chemical shrinkage decreases, the pre - oxidized fiber density gradually decreases, and the boric acid inhibits the chemical reaction of PAN fibers. The inhibition of intramolecular cyclization and intermolecular crosslinking reaction by boric acid can contribute to the improvement of the degree of homogenization of the preoxidation fiber and can prevent the PAN fiber surface from being excessively oxidized at a relatively high temperature.