Effect of carbon nanofibers on thermal conductivity of carbon fiber reinforced composites

Carbon fiber-reinforced composites (CERCs) have been fabricated using a vacuum assisted resin transfer molding (VARTM) incorporating carbon nanofibers (CNFs). Incorporation of CNFs in the composite laminate was performed by both matrix-modification and fiber-modification routes. In the matrix-modification route, vapor grown carbon nanofibers (VGCNFs) were directly mixed into the epoxy resin EPON862 using ultrasound tip sonication. In the fiber-modification route, carbon nanotibers (CNEs) were directly grown on the carbon fiber fabric using chemical vapour deposition (CVD). A wire-based 3 omega technique was used to measure the thermal conductivity of the CFRCs in both in-plane and through-thickness direction. Although the matrix-modification route didn't show significant improvement in the in-plane direction, the fiber-modification route showed improvement in both in-plane and through-thickness directions. Maximum improvement in through-thickness thermal conductivity of about 10% and 30% was observed in the matrix-modification and fiber-modification route, respectively. It is believed that the random orientation of the CNEs on the fiber surface results in such an improvement in the in-plane direction. Effect of temperature on thermal conductivity was also measured and found to be significant for the CNF-modified composites compared to unmodified composites. (C) 2013 The Authors, Published by Elsevier Ltd.