Enhancement of High-Density Polyethylene Properties by Impregnation with Inorganic Alumina Filler

Abstract

The influence of filler size and content on the mechanical and rheological properties (thermal conductivity, impact strength, hardness and melt flow index (MFI) of Al 2 O 3 /high-density polyethylene (HDPE) composites have been studied. Concentration of alumina was varied up to 30% by weight. The composites were prepared using a two-roll mill and then test specimens were prepared by injection molding. Thermal conductivity, hardness, impact strength and melt flow rate of the composites increased with decreased particle sizes and increased particle content with exceptions at certain concentrations due to non-uniform distributions of particles and agglomerates formed by the particles. As an example, the best integrated thermal conductivity was shown by a 75 micron-Al 2 O 3 /HDPE composite at 15% wt. alumina content, while the 212 micron- Al 2 O 3 /HDPE composite at 20 wt.% alumina content. For the same alumina content of 15% concentration by weight out of the three particle sizes. 75, 212 and 850 microns, the 75 micron-Al 2 O 3 /HDPE composite gave the highest thermal conductivity, which was nearly 50% higher than that of pure HDPE. Enhancement in impact strength and Hardness Rockwell were up to 300% and 400% as compared to the pure HDPE respectively. The Al 2 O 3 with small particle size is generally more efficient for the enhancement of the impact strength.