Mechanical properties and morphology of glass bead-filled polypropylene composites

The effects of the filler content and size on the mechanical properties such as tensile modulus, E-c, yield strength, sigma(yc), and impact strength, S-IC, of glass bead-filled polypropylene (PP) composites have been investigated employing an Instron materials tester and a Ceast impact tester at room temperature. With increasing concentration of glass beads, E-c and S-IC increase, but sigma(yc) decreases non-linearly, within a filler volume fraction range of 0%-20%; under the same test conditions, the values of E-C and sigma(yc) for PP with bigger beads are somewhat lower than those of PP with smaller ones; the maximum values of S-IC for the composites are about 1.4 times as high as the unfilled PP; the interface between the matrix and the beads is a weak bond. The results indicate that the stiffness and the toughness of the PP composites are effectively improved by addition of glass beads.