Three-phase lewis-nielsen model for the thermal conductivity of polymer nanocomposites

The thermal conductivity of polymer-based microcomposites has been investigated for a long time. The existing theories predict the thermal conductivity of the polymers filled with conventional sized microparticles quite well. Significant effort has been made in studying and developing of the thermal conductivity behavior of a relatively new class of composites, which contain nanosized filler. A considerable volume of the polymer matrix has a modified structure with respect to the bulk polymer due to polymer-filler bonding via a silane coupling agent (SCA), which has been applied used to improve the thermal contact between the individual components. The thermal conductivity of a nanocomposite depends on the interfacial layer, which can be defined as a transition layer between a host material and incorporated nanofiller, rather then the thermal conductivities of the constituents. A composite material can be represented by composite particles embedded into the polymer matrix. A composite particle consists of a nanoparticle and the polymer close to the particle surface, which is organized by the surface modification. We propose a model for the thermal conductivity of the polymer nanocomposites. This model is intended to be used for systems which consist of a polymer matrix, nanofiller and the interfacial layer around the nanoparticles which has different properties than the bulk polymer.