Nanocomposites with single walled carbon nanotubes (SWNTs) are being investigated to take advantage of the superior properties of SWNTs. While notable successes have been reported for the electrical properties, particularly low percolation thresholds, the remarkable thermal conductivity of SWNTs is proving more difficult to impart to a nanocomposite. We investigate the thermal conductivity of SWNT/polyethylene composites with attention to the effect of the degree of PE crystallinity and the alignment of both the PE and SWNT. The nanocomposites were prepared via the hot-coagulation method with low- and high-density polyethylene, resulting in a good dispersion of the SWNTs in the polyethylene matrix. Characterization methods include the comparative method to measure thermal conductivity, x-ray scattering and polarized Raman spectroscopy to quantify SWNT and PE alignment, and optical microscopy and SEM to determine SWNT dispersion. At 30 wt% SWNT, isotropic composites made with low density and high density PE have thermal conductivities of 1.8 and 3.5 Wm~(-1) K~(-1), respectively, relative to the values of 0.26 and 0.5 Wm~(-1)K~(-1) without SWNTs. Alignment of both the SWNT and PE was produced by melt fiber spuming and results show that the thermal conductivity increase with orientation.
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