Study of the morphology and mechanical properties of polypropylene composites with silica or rice-husk

The mechanical, morphological behavior and water absorption characteristics of polypropylene (PP) and silica, or PP and rice-husk, composites have been studied. The silica used in this study as filler was a commercial type produced from soluble glass or rice husks. The compatibilizing effect of PP grafted with monomethyl itaconate (PP-g-MMI) and/or with vinyltriethoxysilane (PP-g-VTES) as polar monomers on the mechanical properties and water absorption was also investigated. In general, a high loading of the studied fillers in the polymer matrix increases the stiffness and the water absorption capacity. This effect is more noticeable in the tensile modulus of the PP/silica composite with PP-g-VTES as compatibilizer. However, the increase of the rice-husk charge as a natural filler in the PP matrix decreases the stiffness, and in the presence of PP-g-MMI as compatibilizer in PP/rice-husk, the tensile modulus and water absorption of the composite were improved. The better adhesion and phase continuity in the PP/silica and PP/rice-husk composites with different compatibilizers was confirmed by the morphological study. (C) 2004 Society of Chemical Industry.