Effect of carbon nanotube surface modification on thermal properties of copper–CNT composites

Carbon nanotubes (CNTs) were functionalized by polymer wrapping (CNT–PSS) and oxidation (CNT–COOH), followed by reduction of copper ions in hydrogen atmosphere, producing copper decorated carbon nanotubes (CNT–f@Cu). Thus synthesized hybrid nanostructures were used as conductive fillers to tailor the heat transport capabilities of a copper matrix. Thermal properties, i.e. thermal diffusivity and thermal conductivity, of copper composite were measured and compared with those containing pristine and functionalized carbon nanotubes. Experimental results revealed that thermal diffusivity and conductivity of the composites decrease with increasing content of carbon nanotubes. However, composites enriched with nanohybrids where Cu nanoparticles were covalently bonded to carbon nanotubes had thermal conductivity four times higher than those containing the same content of pristine CNTs. The experimental results were analysed using Nan's model which accounts for contributions from thermal interface resistance at metal–CNT boundary as well as aspect ratio of carbon nanotubes.