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采用固相剪切碾磨预处理结合熔融再加工技术制备了高性能铝粉(Al)/线性低密度聚乙烯(LLDPE)导热复合材料,并与常规熔融共混法对比,系统研究了固相剪切碾磨对复合材料微观形态、结晶性能、热稳定性、流变特性、热导率和力学性能等的影响。结果表明:通过固相剪切碾磨实现了球形Al颗粒应力诱导变形为具有较大径厚比的片状,在基体中均匀分散且与其界面结合得以增强,同时这种大片状的铝粉在Al/LLDPE复合材料成型时更易有效接触形成导热网链并形成一定取向分布,特别是在高填充量下。因此Al/LLDPE复合材料拥有更好的结晶性能和热稳定性、更低的流变逾渗阈值、更高的热导率和力学性能。固相剪切碾磨预处理制备的Al/LLDPE复合材料在铝粉含量超过15%就出现流变逾渗现象,且当Al填充质量分数80%时,复合材料的热导率高达8.86 W/(m·K),拉伸强度和弯曲强度分别为33.0 MPa和31.2 MPa,都明显优于常规熔融共混复合体系,同时其初始分解温度也提高了近13℃。
High-performance aluminum / linear low density polyethylene (LLDPE) thermal conductive composites were prepared by solid state shear milling pretreatment combined with melt reworking. Compared with the conventional melt blending method, the solid phase Effect of shear milling on the microstructure, crystallinity, thermal stability, rheological properties, thermal conductivity and mechanical properties of the composites. The results show that the stress-induced deformation of the spherical Al particles into a sheet with a large diameter-thickness ratio is achieved by solid-state shearing and milling, uniformly dispersed in the matrix and strengthened at the interface with the aluminum particles, and at the same time, the large- In the Al / LLDPE composite molding easier and more effective contact formation of heat conduction network chain and the formation of a certain orientation, especially at high loading. Therefore, Al / LLDPE composite has better crystallinity and thermal stability, lower rheological percolation threshold, higher thermal conductivity and mechanical properties. The Al / LLDPE composites prepared by solid state shear milling preformed rheological percolation when the aluminum content exceeded 15%, and the thermal conductivity of the composites reached as high as 8.86 W / (m · K). The tensile strength and flexural strength were 33.0 MPa and 31.2 MPa, respectively, which were significantly better than that of the conventional melt blending system. Meanwhile, the initial decomposition temperature increased by nearly 13 ° C.