EFFECT OF FLY-ASH CONTENT AND COUPLING AGENT ON THE MECHANICAL-PROPERTIES OF FLY-ASH-FILLED POLYPROPYLENE

Flyash to 20 wt% was added to polypropylene and an ethylene/propylene copolymer with and without the addition of a maleic anhydride grafted polypropylene coupling agent. The tensile mechanical properties were assessed and the fracture toughness measured by using notched impact specimens. The modulus of the materials increased with the addition of the filler and further increased with the addition of the coupling agent while the yield stress decreased with the addition of 10 wt% filler and no coupling agent but was unchanged from the matrix when the coupling agent was added. Elongation to break was significantly less in those composites to which the coupling agent had been added. Scanning electron microscopy showed that bonding between the matrix and the filler was significantly improved by the addition of the coupling agent and this appeared to hinder the drawing mechanisms in the polymer. The fracture toughness in the copolymer based composites was seen to decrease with filler content.