Abstract
Highly filled polypropylene composites have been prepared with filler contents up to 43.8 vol.% (70 wt.%) after surface treatment of the fillers with titanate or silicone. The fillers used were calcium carbonate, talc and barium sulfate. Surface modification of the fillers facilitated extrusion and reduced brittleness while providing hard composites with high density. The high density and hardness provide a texture which is not characteristic of polypropylenes, but more like thermoset composites or ceramics; yet the composites can be extruded using typical thermoplastic processing equipment. The composition has been measured by thermogravimetry, and morphology observed with scanning electron microscopy. The tensile properties were measured and related to the composition, filler type and surface treatment.