Effect of graphite and carbon fiber contents on the morphology and properties of thermally conductive composites based on polyamide 6

Composites of polyamide 6 (PA 6), powdered synthetic graphite and pitch‐based carbon fiber were melt processed to explore the effect of the filler contents on the anisotropic properties of the resulting composites. Optical microscopy and mechanical properties were used to determine the dispersion of graphite and carbon fiber in the PA 6 matrix. The relationship between the structure and properties showed the anisotropic filler orientation along the three principal directions. Thermal expansion in the flow direction and transverse direction decreased as filler content increased for all composites, but the decrease in the flow direction was much more significant. This anisotropic orientation also influenced the thermal conductivity of the composites resulting in an increased in‐plane thermal conductivity up to 25 times that of pure PA 6. Thermography shows good agreement with the thermal conductivity results. © 2013 Society of Chemical Industry Thermally conductive composites of graphite and carbon fiber in PA 6 matrix was prepared by melt compounding. The composites with high filler loading and hybrid filler system show the enhanced thermal conductivity values indicating the possibility to use for a heat sink.