同轴静电纺丝再经两步后处理制备PAN基中空碳纤维

采用聚丙烯腈(PAN)溶液作为壳层,甲基硅油作为芯层,利用同轴静电纺丝技术制备出外径为3μm的同轴PAN复合纤维,经过预氧化和炭化后可以制得直径约为1μm的中空碳纤维.采用扫描电镜(SEM)观察中空纤维形貌.傅立叶红外光谱分析仪(FTIR)表征了热处理前后纤维成分变化.分析了同轴射流结构、芯液/壳液流速比Vin/Vout对中空结构的影响.研究表明,同轴内针尖伸出外针尖的距离Zp是影响同轴射流形成的主要因素,伸出长度Zp约为外针孔半径rout的1/2时得到同轴射流,Zp>0.7rout时从冠状锥体周围产生许多射流,不能在锥顶部形成同轴射流.芯液/壳液流速比Vin/Vout对中空结构的形成有较大影响,当Vin/Vout=0.5时得到多孔纤维,增大芯液流速,当Vin/Vout=1时得到中空纤维,继续增大Vin/Vout=2时得不到同轴射流.

FABRICATION OF PAN-BASED HOLLOW CARBON FIBERS BY OAXIAL ELECTROSPINNING AND TWO POST-TREATMENTS

Core/shell polyacrylonitrile(PAN)fibers with an outer diameter of 3 μm were prepared by coaxial electrospinning using silicon oil as the core and PAN solution as the shell.After oxidation-stabilized and high-temperature pyrolyzed,some hollow carbon fibers with an outer diameter of 1 μm can be obtained.Morphologies and structural changes of the fibers were characterized by scaning electron microscopy(SEM)and Fourier-transform infrared(FTIR)spectroscopy respectively.Effects of coaxial spinneret and feeding rate ratio of the inner and the outer liquids(V_ in /V_ out)were studied on the formation of the coaxial fibers.Results showed that the net length of the core nozzle over the shell nozzle,Z_p,affected the formation of the core-shell jets greatly:when Z_p was about half of the shell nozzle radius(r_ out),a coaxial jet could be obtained on the tip of the coaxial spinneret;but if Z_p increased larger than 0.7r_ out,the shell fluid was splitted into multiple jets.In addition,feeding rate ratio also had a great influence.Coaxial fibers could be obtained when V_ in /V_ out =1,whereas either porous fibers were obtained when V_ in /V_ out =0.5,or a single PAN solution jet and silicon oil droplets were obtained when V_ in /V_ out =2.