Environmentally friendly wood adhesive from a renewable plant polymer: characteristics and optimization

A wood adhesive was prepared from a natural renewable resource. The charact eristics and optimization of starch and polyvinyl alcohol (PVOH)-based cros slinked adhesive suitable for wood-to-wood bonding in interior applications are described. The crosslinker, hexamethoxymethylmelamine (Cymel 323) prod uced effective crosslinking through a transetherification reaction between methoxy groups in Cymel 323 and hydroxyl groups in starch, PVOH and wood, w here hydroxyl groups replaced methoxy groups forming ether bonds with the c rosslinker. Optimal viscosity of the adhesive was obtained at 27% solid con tent. Addition of latex in the formulation increased moisture resistance. T he optimum cure temperature and cure time were 175 degreesC and 15 min. Woo d samples conditioned at 93 % RH for two months exhibited > 95% failure in wood but little in adhesive joints. Scanning electron microscopy revealed n o visible growth of fungi or other microorganisms on the adhesive after two months exposure of samples at 97% RH followed by 1 year at 50% RH. Publish ed by Elsevier Science Ltd.