Effect of metallic fillers on the hardness of polystyrene composites: An experimental investigation

In this study, the effects of composite thickness (2.5-7.5 mm), filler content (15-45%w/w) and particle sizes (20-100 µm) on the hardness of Polystyrene metal composites were examined. The metals comparatively considered were aluminium particles and iron fillings. It was observed that smaller metal particle sizes in the composite matrix and greater filler proportions will lead to improvement in hardness. Composite thickness did not have a significant effect on the hardness of the metal composites. PS-Al composite is harder than PS-Fe composite with the optimal hardness being 43.7 and 11 respectively. The factor levels that will optimise hardness for PS-Al composite are thickness of 7.5 mm, filler of 39% and particle size of 20 µm. For PS-Fe composites they are thickness of 5.9 mm, filler of 45% and particle size of 34µm. The metallic composites (PS-Al and PS-Fe) exhibited contrasting mechanical strength when viewed under SEM with a homogenous micro-structure of high interfacial interaction between the metal particles (Aluminium) and the PS resin matrix while the PS-Fe metallic composite under micro-structural analysis displayed relatively moderate to low tensile strength and hardness with weak interfacial interaction between the Iron particles and the PS resin.