Effect of glass filler surface treatment on flexural properties of polypropylene composites

The effect of glass particle surface treatment on the flexural properties of glass particle reinforced polypropylene composites was investigated. The glass particles used were glass beads, glass milled fibers (average length 26 mu m), and glass cut fibers (average length 100 mu m). The glass particles were treated with six kinds of silane coupling agents with different organic functional groups. The wettability of glass plates treated with these coupling agents was also estimated by measurement of contact angles using thirteen liquids. It was found that composite flexural properties correlated with wettability of the glass plate when both the glass particles and glass plate were treated with the same coupling agent. For the case where the organic functional group comprised an alkyl group, the composite flexural rigidity and strength decreased with increasing critical surface tension calculated from the contact angles of halogen-containing liquids.