Aluminum/polypropylene composites produced through injection molding

The contact angles of molten polypropylene on metals with different surface conditions were examined. A quantitative relation between the surface topography and mechanical strength as well as the optimum dimensional scope of the topography feature for achieving good mechanical performance was determined. High metal temperatures facilitated the filling of the surface features by the polymer melt. The interfacial strength between the metal surface and polymer was dramatically improved by increasing the metal temperature approximately to the heat-distortion temperature of polypropylene. The fracture mechanism of the polymer-metal hybrid structures as well as the correlation between the crystallinity of polypropylene near the interface and the bonding strength was examined. The beta-crystals were found to have a significant effect on the mechanical performance of the polymer-metal hybrid structures.