RICE HUSK ASH AS FILLER IN UNSATURATED POLYESTER BASED SHEET MOULDING COMPOUNDS (SMC)

Abstract

Sheet moulding compounds were made from unsaturated polyester resin as matrix material filled with calcium carbonate, white rice husk ash and black rice husk ash. The objective of this investigation was to utilize the white and black rice husk ash, which are available in large quantities and which pose environmental problems in rice-producing areas. The investigation showed that black ash has a profound effect to increase the modulus of rupture, modulus of elasticity, as well as to reduce the thickness swelling and water absorption. Scanning electron microscopic studies showed that the black ash retained the fibrous morphology and thus has a better reinforcing function than white ash, which is amorphous. Reduction in water absorption and thickness swelling should be attributed to the hydrophobic nature of carbonaceous residues present on the outer surface of black ash. Formation of organosilicon compounds during the processing of the black ash was at first suspected to be responsible for the water repellency; but the 29Si MAS NMR studies did not provide evidence for the formation of such compounds.