Formulation and Performance Evaluation of Wood Adhesives Produced with Rice Husk Ash as New Filler

Abstract

This study investigated the applicability of rice husk ash (RHA) as filler in wood adhesives containing a blend of ethylene acrylic resin, poly vinyl acetate resin and natural rubber solution. Rice husk, obtained from Rice Mill Industries in Abakaliki, Nigeria, was washed, dried and heated to char (carbonized) on a gas stove until there was no emission of fumes. The rice husk char obtained was incinerated under controlled conditions in a muffle furnace at 650oC for four (4) hours. The RHA obtained was ground with ceramic mortar and pestle to reduce the particle size, sieved with a standard 63μm sieve and then used as filler in acrylics/PVA/NR wood adhesive. Filler levels in the adhesives were varied from 0 to 16%. The bond strength and thermal resistance of the prepared adhesives were determined and compared with that produced with CaCO3 as well as a popular brand in the Nigerian market, Top Bond, used as reference standard. The result showed that after application, there was a general increase in bond strength with time for both CaCO3 and RHA adhesives. The highest bond strength was obtained at a filler level of 12% for both fillers. At this level, RHA adhesive had higher bond strength of 170.3 KPa than CaCO3 adhesive which had 167.8 KPa. RHA-filled adhesives were found to be more thermally stable than those of CaCO3 and comparable to the reference standard.