Preparation and Performance of High Thermal Conductivity Polypropylene-based Composites

Polypropylene-based composites with high thermal conductivity were obtained by pressure injection molding using a hybrid form of PP as the matrix and FG as the thermally conductive filler with a particle size of 37 µm. Microscopic morphologies of the material were examined by SEM to determine the effect of FG content on the thermal conductivity and mechanical properties of the composites. The study found a clear correlation between the thermal conductivity of the composites and the FG content. The research confirmed a direct link between the thermal conductivity of the composites and FG content. At 70 wt%, the material demonstrated the greatest average, axial, and radial thermal conductivity of 7.52 W·m-1·K-1, 12.6 W·m-1·K-1, and 4.50 W·m-1·K-1, respectively.  However, any subsequent increase in fractional gradient (FG) content resulted in a decrease in the strength and modulus of the material. The highest tensile and flexural strength values of 34.9 and 63.7 MPa respectively, were achieved when the FG content was 60 wt%. At this particular FG content, the tensile and flexural modulus also reached 9.78 and 10.7 gigapascals (GPa), respectively. As the FG content increased, the strain on the composite material decreased. Note that the maximum tensile and flexural strains were measured at 50 wt% FG content, with values of 0.77% and 0.79%, respectively. The glass fiber sheets in the injection molded composites were uniform and predominantly vertically oriented.