混酸处理对预氧化聚丙烯腈纤维结构和性能的影响

以化学改性的原理,用盐酸和硫酸的混合酸对预氧化聚丙烯腈纤维进行了处理,用红外光谱、DSC、元素分析、裂解色谱-质谱和强度的测定等手段对处理结果进行了研究。分析表明,经混酸处理后在纤维中引进的羧基能够使纤维在随后的高温处理中引发二次环化反应,使得聚合物分子链间的交联度增加、耐热性提高及高温裂解得到抑制,致使最终炭纤维的强度提高了16.3%。

Effect on Structure and Properties of Pre-Oxidized Polyacrylonitrile Fibers Via Mixed Acid Treatment

From the mechanism of chemical modification,Pro-oxidized polyacrylonitrile fibers were treated by the mixed acid of hydrochloric acid and sulfuric acid to improve performances of the fibers and enhance tensile strength of corresponding carbon fibers.Treatment result was investigated by means of infrared spectra,DSC,element analyse,pyrolysis gas chromatography-mass spectrometry and tensile strength testing etc.If indicates that carboxyl groups are effectively introduced in polymer chains during the mixed acid treatment.Subsequently the carboxyl initiates secondary cyclization reaction of residual cyanogen groups of polymer linear chains in high temperature.The reaction increases polymer cross-linking degree,enhances the fibers heat-resistance and restrains the chains pyrolysis leading to the final carbon fibers having more graphite-like structure.The ameliorative fibers structure makes the tensile strength of the carbon fibers enhancing by 16.3% comparative to the fibers without treatment.