Thermal conductivity of graphite filled liquid crystal polymer composites and theoretical predictions

Composites of liquid crystal polymer (LCP) and powdered synthetic graphite were melt processed to explore the effect of the filler contents on the properties of these composites. Morphology and mechanical properties were evaluated to correlate the filler alignment with mechanical properties. The difference observed in Izod impact strength between the far and gate ends of these specimens stems from the difference in the morphology. Thermal expansion decreased as filler content increased for all composites, but the decrease at high filler loading was less significant. Measurement of thermal conductivity for the resulting composites shows very high value up to 28.3 W/m K that is 71-fold increase compared to the pure LCP. To our knowledge, this thermal conductivity value is the highest one for thermally conductive polymer composites without any filler modification among the many similar reports. Thermographic images for heat releasing behaviors show good agreements with the thermal conductivity results indicating the rapid temperature drops for these composites. Various models have been compared to predict the evolution of thermal conductivity of the composites and shows acceptable prediction to experimental results.