基于工程化设备通过调控纺丝温度提高中间相沥青炭纤维力学和导热性能

Improving the mechanical properties and thermal conductivity of mesophase-pitch-based carbon fibers by controlling the temperature in industrial spinning equipment

基于工程化设备,在恒定挤出量条件下,通过调控纺丝温度制备了中间相沥青炭纤维(MPCFs),探究纺丝温度对MPCFs微观结构、力学和导热性能的影响。结果表明:随着纺丝温度由309升高至320℃,MPCFs的微观结构由石墨片层细小的褶皱劈裂辐射状结构逐步向石墨片层粗大的劈裂辐射状结构转变,拉伸强度由2.16增大到3.23 GPa,热导率由704升高到1078 W·m^(−1)·K^(−1)。这主要是因为纺丝温度越高,沥青熔体黏度越小,喷丝口处挤出胀大效应越弱,沥青熔体在喷丝孔流道内形成的微晶取向得以保持,以此制备的炭纤维具有更大的晶体尺寸和更高的微晶取向。

Mesophase-pitch-based carbon fibers(MPCFs)were prepared using industrial equipment with a constant extrusion rate of pitch while controlling the spinning temperature.The influence of spinning temperature on their microstructures,mechanical properties and thermal conductivities was investigated.SEM images of the fractured surface of MPCFs show that the graphite layers have a radiating structure at all spinning temperatures,but change from the fine-and-folded to the large-and-flat morphology when increasing the spinning temperature from 309 to 320℃.At the same time the thermal conductivity and tensile strength of the MPCFs respectively increase from 704 W·m^(−1)·K^(−1)and 2.16 GPa at 309 oC to 1078 W·m^(−1)·K^(−1)and 3.23 GPa at 320℃.The lower viscosity and the weaker die-swell effect of mesophase pitch at the outlets of the spinnerets at the higher spinning temperature contribute to the improved orientation of mesophase pitch molecules in the pitch fibers,which improves the crystallite size and orientation of the MPCFs.