Investigations on the thermal conductivity of composites reinforced with carbon nanotubes

Composites using carbon nanotubes (CNTs) as the reinforcement and polymethylmethacrylate (PMMA) as the matrix were fabricated. CNTs including single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were prepared through the floating catalyst chemical vapor deposition (CVD) method. CNTs with and without acid treatments were adopted to study the effects of acid-treated CNTs on the thermal conductivity of composites. For comparison, buckypapers composed of loose CNTs were also prepared and tested. In this work, thermal conductivities of composites reinforced with 1.0 wt.% SWCNTs and 4.0 wt.% MWCNTs are 2.43 W/mK and 3.44 W/mK, respectively. The experimental results indicated enhancement of thermal conductivities over tenfold and near fifteen fold higher than PMMA for SWCNTs/PMMA and MWCNTs/PMMA composites, respectively. However, composites reinforced with acid-treated CNTs showed relatively low thermal conductivity. The mechanism of thermal conductivity for various composites is discussed. Temperature-dependence thermal conductivities of the composites reinforced with different ratios of CNTs were measured. Microstructures of composites reinforced with different loadings of CNTs were also studied. (C) 2008 Elsevier B.V. All rights reserved.