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为了研究鳞片石墨在基体中的取向对复合材料导热性能特别是不同方向导热性能的影响,通过双螺杆挤出混合及注射成型制备了鳞片石墨/聚丙烯(PP)、鳞片石墨/尼龙66(PA66)导热复合材料,并利用扫描电子显微镜和超声波测试对制备的样品进行了分析。结果表明:鳞片石墨的粒径越小,平面取向度越高,平面与垂直方向的热导率差值越大。加工中双螺杆挤出机的过度剪切会破坏鳞片石墨的片层结构,影响鳞片石墨导热网络的形成,降低复合材料的热导率,但提高了材料导热的各向均匀性。适度的剪切可以打开鳞片石墨的片层结构,提高复合材料的热导率,注射成型更多影响到制品导热的各向异性。
In order to study the effect of flake graphite orientation in the matrix on the thermal conductivity of composite materials, especially the thermal conductivity in different directions, flake graphite / polypropylene (PP), flake graphite / nylon 66 (PA66 ) Thermal conductive composites, and the prepared samples were analyzed by scanning electron microscopy and ultrasonic testing. The results show that the smaller the particle size of graphite flake, the higher the plane orientation degree, the larger the difference of the thermal conductivity between the plane and the vertical direction. Excess shear in the twin-screw extruder will destroy the lamellar structure of flake graphite, affect the formation of flake graphite thermal conductivity network, and reduce the thermal conductivity of the composite, but improve the uniformity of the thermal conductivity of the material. Moderate shear can open the flake graphite sheet structure, improve the thermal conductivity of composite materials, injection molding more affect the anisotropy of thermal conductivity.