THERMAL-CONDUCTIVITY OF A POLYETHYLENE FILLED WITH DISORIENTED SHORT-CUT CARBON-FIBERS

Thermal conductivity of polyethylene composites, filled with randomly dispersed and disoriented (oriented at random) carbon fibers with various aspect ratios, were investigated. Orientation of fibers was quantitatively evaluated by Hermans' parameter. In specimens of isotropic composites, i.e., filled with randomly dispersed and disoriented fibers, thermal conductivity increased with an increase in the fiber length. The result is discussed in comparison with electric conductivity of the composites and explained by the contact probability of filled fibers. Further, it was confirmed that our model previously proposed could be adopted to predict thermal conductivity of the isotropic composite filled with carbon fibers. Also, the effect of fiber length of the C2 parameter included in the model is discussed and C2 was found to have a linear relation with the aspect ratio of fibers at a sufficiently large value. In this study, a shape factor of a filler (aspect ratio) could be directly introduced into the equation, which was shown in our previous paper.