溶胶共混纺丝制备水性中间相沥青基碳纤维

Preparation of aqua-mesophase pitch-based carbon fibers via sol-gel spinning process

以针状焦(GNC)为原料,采用混酸一步氧化法制备水性中间相沥青(AMP)、混酸两步氧化法制备改进水性中间相沥青(FHAMP),分别与聚丙烯腈(PAN)共混溶解于二甲基亚砜(DMSO)形成溶胶,然后以稀硫酸为凝固剂,经溶胶纺丝、直接炭化制得水性中间相沥青基碳纤维;研究了AMP和FHAMP的溶解性、流变性、可纺性,以及相应的碳纤维的结构与性能。结果表明:相比AMP,FHAMP的粒径显著减小,氧化程度更高,能更好地溶解于DMSO;引入PAN,可有效提高AMP和FHAMP溶胶的可纺性;在纺丝温度50℃时,PAN质量分数为10%的AMP溶胶及PAN质量分数为8%的FHAMP溶胶均有较好的可纺性,连续收丝长度超过1000 m,FHAMP溶胶的纺丝稳定性更好;相比由AMP得到的碳纤维,由FHAMP得到的碳纤维截面结构较为致密,纤维直径减小至23.09μm,杨氏模量和拉伸强度分别提高至33 GPa和0.29 GPa。

Using green needle coke(GNC)as raw material,an aqua-mesophase pitch(AMP)was prepared via one-step mixed acid oxidation and a modified aqua-mesophase pitch(FHAMP)was prepared via two-step mixed acid oxidation.Sol solutions were discovered for sol-gel spinning by separately dissolving AMP and FHAMP in dimethylsulfoxide(DMSO)along with polyacrylonitrile(PAN)using dilute sulfuric acid as a coagulant,followed by direct carbonization to aqua-mesophase pitch-based carbon fiber.The solubility,rheological behavior and spinnability of AMP and FHAMP,as well as the structure and properties of the corresponding carbon fibers,were studied.The results showed that compared with AMP,FHAMP had much smaller particle size,higher oxidation degree and better solubility in DMSO;the introduction of PAN can effectively improve the spinnability of AMP and FHAMP sol;the AMP sol containing 10%PAN by mass fraction and FHAMP sol containing 8%PAN by mass fraction both had good spinnability when the spinning temperature was about 50℃,but the spinning stability of FHAMP sol was better when the continuous spinning length exceeded 1000 m;compared with the carbon fiber obtained from AMP,the carbon fiber obtained from FHAMP had more compact cross-section structure and the fiber diameter decreasing to 23.09μm,the Young′s modulus and tensile strength increasing to 33 GPa and 0.29 GPa,respectively.