Electrical and thermal conductivities of carbon fiber composites with high concentrations of carbon nanotubes

Abstract

High concentrations (1.1–3.7 wt%) of carbon nanotubes (CNTs) were incorporated into carbon fiber (CF)-reinforced epoxy composites by different fabrication methods. A mat-like form of CNT (CNT mat) was inserted between plies of CF plain-weave fabric and the composite was processed by vacuum-assisted resin transfer molding (VARTM). Two similar CNT structures, CNT mat and buckypaper, were inserted between CF woven prepreg laminates and the corresponding CF prepreg composites were fabricated by curing either in an autoclave or in a hot press. For the final method, CNTs were directly grown onto CF plain weave fabric and hierarchical composites were fabricated from those CNT-CF fabrics by the VARTM method. Out-of-plane electrical and thermal conductivities were evaluated for the fabricated composites. Electrical conductivity was enhanced most for the hierarchical composites; thermal conductivity, for the CF fabric composites with CNT mat. The results are discussed in conjunction with optical microscopy images of the composites’ cross-sections.