Abstract: Using flake graphite with particle size 15 μm and alumina with particle size 3 μm as thermally conductive filler, and novel corotating nonsymmetric twinscrew extruder as processing machine, thermally conductive polymers of PP/Al2O3 and PP/Al2O3/graphite were prepared at the filling content of 10 % graphite and 10 %~50 % alumina, respectively. It was found that the addition of a small amount of graphite may increase the tensile, bending, and impact strengths of PP/Al2O3 composites. Melt flow rate of PP/Al2O3/graphite was smaller than PP/Al2O3, and HDT of PP/Al2O3/graphite increased about 15 % based on PP/Al2O3.

Key words: co-rotating non-symmetric twin-screw, polypropylene, graphite, aluminum oxide, thermally conductive composite