Rheological behaviors of plasticized polyvinyl chloride thermally conductive composites with oriented flaky fillers: A case study on graphite and mica

In this study, two oriented flaky fillers in plasticized polyvinyl chloride (P-PVC) matrix were respectively compared on some rheological behaviors such as dynamic rheological behavior, melt flow rate, and Barus effect. By comparing and analyzing the rheological behaviors and thermal conductivity of P-PVC/graphite and P-PVC/mica composites with oriented fillers, it is found that the P-PVC/graphite composites have obvious percolation thresholds of viscosity, modulus and thermal conductivity at 23.6 vol%. However, P-PVC/mica composites did not show similar phenomenon. Moreover, the variable parameter K′ in the modified Kerner–Nielson equation was used to relate the rheological behavior, percolation concentration and thermal conductivity of the composites, and the formation of the filler network was analyzed through the rheological behavior to explain the influence of the percolation threshold in the composites caused by the change of internal structure on the thermal conductivity. It has important guiding significance for the mechanism research and comprehensive performance improvement of the filled composites.