纺丝工艺对T800碳纤维及其复合材料性能的影响

采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线光电子能谱仪(XPS)和表面接触角测量仪分别对湿法纺丝(T800HB)与干喷湿纺(T800SC)两种纺丝工艺制备的T800碳纤维表面状态进行表征和分析,采用万能材料试验机对二者的复丝、NOL环及单向板的力学性能进行对比研究。结果表明:湿法纺丝的T800HB碳纤维具有更粗糙的表面,而干喷湿纺T800SC碳纤维具有更高的表面活性,“化学活性”和“机械啮合”的共同作用使得两种碳纤维复合材料具有相近的层间剪切强度。但当复合材料发生破坏时,T800HB碳纤维与树脂间“机械啮合”的主导作用更显著,纤维/树脂结合更紧密,使得其复合材料的断裂呈脆性破坏模式,而T800SC碳纤维与树脂结合则稍弱,呈一定程度的韧性破坏模式。T800SC碳纤维比T800HB碳纤维具有更高的复丝拉伸强度,因而相应地,T800SC碳纤维复合材料NOL环和单向板均有更高的拉伸强度。因此,综合两种不同纺丝工艺碳纤维及其复合材料的力学性能和破坏形貌,相比于T800HB,T800SC碳纤维更适合作为缠绕成型复合材料的增强材料。

Effect of spinning process on the properties of T800 carbon fiber and its reinforced composite

The surface conditions of the two different T800 carbon fibers by the wetting (T800HB) and the dry jet-wetting spinning processes (T800SC) were characterized and analyzed by scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscope (XPS) and contacting-angle measuring instrument. The mechanical properties of their multifilaments, NOL rings and unidirectional laminates were evaluated by universal material testing machine. Results show that the surface of T800HB by wetting process is rougher, while the surface of T800SC by dry jet-wetting process is more chemical-active. Both chemical interaction and mechanical engagement between fiber and resin matrix result in the similar interlaminar shear strength (ILSS) of T800HB and T800SC. However, when the composite is damaged, the interfacial bonding of T800HB/resin seems tighter dominated by the mechanical engagement, leading to brittle fracture feature of T800HB reinforced composite, while T800SC reinforced composite exhibits ductile fracture feature with weaker interfacial bonding. In addition, the tensile strength of filament of T800SC is higher than that of T800HB. Accordingly, the tensile strength of NOL ring and unidirectional laminate composite of T800SC are higher than those of T800HB. Therefore, in combination of mechanical properties of carbon fibers by two kinds of spinning processes and their reinforced composites, as well as their fracture features, compared with T800HB, T800SC is more suitable to be the reinforcement of the composite fabricated by filament winding process.