聚丙烯腈(PAN)碳纤维由有机纤维经过高温处理得到,其结构和性能与热处理时间密切相关。采用固体核磁共振碳谱仪、热失重分析仪、X射线衍射仪和力学性能分析等研究了热处理时间对预氧纤维结构、碳纤维结构和性能的影响。结果表明:预氧化时间的延长使环化、脱氢和氧化反应形成的—CN、CC、CCH、CO含量增加,使预氧纤维的稳定性增强,形成的碳纤维微晶尺寸较小、层间距较大,碳纤维拉伸强度和拉伸模量较大,但体密度较低;随着碳化时间的延长,纤维的热稳定性呈现先下降后增强的趋势,碳纤维的微晶尺寸增大,层间距减小,碳纤维的体密度、拉伸强度和拉伸模量增加。

Polyacrylonitrile (PAN) carbon fibers were obtained by high temperature heat treatment of organic fibers.Its structure and performance were closely related to the heat treatment time.Using solid-state ¹³C-NMR,TG,XRD and mechanical property analysis,the effects of heat treatment time on the structure of pre-oxidized fibers were studied by changing the pre-oxidation and carbonization treatment time.The structure and property of carbon fibers were studied by the same method.The results showed that the content of —CN,CC,CCH and CO formed during pre-oxidation and the stability of pre-oxidation fibers all increased with the increase of pre-oxidation time.The size of microcrystallite in carbon fibers was smaller and the interlayer spacing was larger.The tensile strength and modulus of carbon fibers were higher but the bulk density was relatively lower.With the increase of carbonization time,the thermal stability of fibers first decreased and then increased,the crystallite size of carbon fibers increased,and the interlayer spacing decreased.The bulk density,tensile strength and tensile modulus of carbon fibers all increased.