Thermal properties of silicon powder filled high-density polyethylene composites

Thermal conductivity and coefficient of thermal expansion (CTE) of silicon particulates reinforced high-density polyethylene (HDPE) composites are reported. Composite samples were fabricated by mixing the components in proper volumetric ratio, molding and hot pressing. Incorporation of Si powder in HDPE enhances both the thermal stability and the effective thermal conductivity of the composites. CTE of the composites display substantial reduction with increasing Si content in HDPE, while with increasing temperature CTE increases linearly. Effective thermal conductivity for HDPE containing 20-volume fraction (%) Si becomes double than that for unfilled HDPE. Results on both the effective thermal conductivity and CTE of the composites have been discussed in light of various theoretical models. Our analysis confirms that the effective thermal conductivity of HDPE/Si composites is predicted extremely well by the model proposed by Agari et al. and conductive channels are not easily formed in HDPE/Si composites. We also show that CTE data could be successfully explained taking into account the role of the interphase volume and the strength of the polymer–filler interactions.