Prediction of the Effective Thermal Conductivity of Carbon Nanotube-Reinforced Polymer Systems

A study dealing with the effect of the carbon nanotubes (CNTs), at various weight fractions, on the effective thermal conductivity of a CNT-reinforced polymer by associating it with the Kapitza resistance (R-Kap) phenomena is presented. The finite element method was utilized as a tool for the models' solution by using the principles of the representative volume element. An intermediate continuum layer between polymer matrix and CNTs was considered for the representation of the R-Kap phenomena. The influence of the intensity of R-Kap phenomena at various CNT contents was investigated through the parametric study of the R-Kap value and the thickness of the intermediate layer. The predicted results were compared against experimental measurements derived from an equivalent CNT-epoxy resin system. The discrepancy between calculated and measured values is diminished when the R-Kap phenomena are taken into account, thus confirming the existence of thermal resistance between the CNTs and the polymer matrix. The R-Kap rise as the % CNT weight content is increased. This behavior is correlated to the higher CNT agglomeration at higher CNT contents, which is proven by the scanning electron microscopy and thus providing a first indication of the effect of the CNT agglomeration on the effective thermal conductivity at various CNT contents. (C) 2014 Society of Plastics Engineers