碳纤维自焊接骨架结构的形成及其复合材料性能研究

Properties of Polymer Composites Reinforced by Self-welded Carbon Fiber Networks

报道了一种将短切碳纤维(CF)自发焊接成三维网络结构的新方法.研究发现,尼龙6(PA6)与CF具有较强的相互作用,SEM照片及储能模量高温平台表明,添加少量PA6能够在PS基体中形成耐高温的CFPA6自焊接骨架结构,PA6用量越多,高温储能模量越高,自焊接骨架结构强度越大.研究证明,这种自焊接骨架结构能够大幅度提高PS/CF复合体系的热变形温度,碳纤维具有优异的导电导热性能,碳纤维骨架结构能够降低导电临界浓度,增强面内导热系数.进一步分析表明,PA6在碳纤维表面定向聚集是一个动力学过程,CF-PA6自焊接骨架强度与PA6黏附率NPA6呈线性关系;扩大PA6与PS的黏度差,延长热压时间均有利于提高NPA6,进而大幅提高网络结构强度.

A new approach to self-weld the short carbon fiber （CF） into network throughout the matrix was proposed in this study. It was found that, CF owns strong interactions with nylon 6 （PA6） , and adding small amount of PA6 leads to the formation of CF-PA6 networks in the PS matrix, as shown in SEM images and reflected by the platform of storage modulus at higher temperatures. Increasing the contents of PA6 improves the storage modulus at high temperatures,and enhances the strength of the self-welded networks. As a result, the ternary composites behave a remarkable increase in the heat distortion temperature. As carbon fiber possesses superior thermal and electrical conductivity, the composites show a lower electrical percolation threshold and a higher in-plane thermal conductivity. Further analysis demonstrated that the encapsulation of PA6 on the CF surface is a kinetic process, and the storage modulus at 180℃ increases linearly with encapsulation ratio of PA6, NPA6. Experimental results confirm that a larger difference in viscosities between PA6 and the matrix is benefit for increasing NPA6, while a longer hot-press time promotes preferential segregation of PA6 on the CF surface and further toward the intersections of CF, and thus greatly improves the mechanical strength of the networks.