Abstract
In this work, we prepared carbon nanotubes/polymethyl methacrylate(CNTs/PMMA) composites and measured its thermal conductivity by the Transient Plane Source (TPS) method. Moreover, we prepared CNTs buckypapers from CNTs suspension and measured its thermal diffusivity by the laser flash method for calculating the thermal conductivity of the buckypapers. The thermal conductivity of the composites fabricated from buckypapers was also investigated, the results were compared with the theoretical predictions. The effects of purification, test temperature and anisotropy of CNTs on thermal conductivity of the composites were investigated. The influences of the purification process on CNTs was analyzed by Thermogravimetry Analyzer (TGA)、Raman Scattering Spectrometer (Raman) and Field Emission Scanning Electron Microscopy (FESEM). FESEM images showed that the catalysts metals in CNTs were reduced after the purification process. The TGA results showed that thermal stability of CNTs was improved after purification, but the structure of carbon nanotubes was also damaged. The thermal conductivities at room temperature of SWNT and MWNT films were 2.24 W/m K, and 0.36 W/m K, respectively. The thermal conductivities of CNT films increased with decreased of temperature. In this study, the highest thermal conductivity of W/m K was attained when the unpurified MWNTs loadings reaches 4.0 wt %, which is over 10 times higher than the thermal conductivity of PMMA. The thermal conductivity of composites increases with CNT loadings and temperature was also detected.