Abstract
Fracture toughness of polypropylene (PP) and its composites has been investigated in relations to the crystallinity of PP, to the glass bead filling and to the surface treatment of glass bead. Raw materials used for the matrix were the high crystalline PP and the general purpose PP. The crystallinity of PP was controlled by the cooling conditions after the hot press molding of PP. The glass beads were treated with various silane coupling agents. The fracture toughness of PP and its composites, measured by the compact tension type test pieces, has decreased remarkably with the increase of the crystallinity of PP. In the case where the crystallinity of PP is low (<49%), the fracture toughness has increased by the filling of the glass beads, and it has further increased by the surface treatment of glass beads. The wettability (the critical surface tension) of the glass plates treated with various coupling agents has shown good correlation with the fracture toughness for the low crystalline composites.
