Submitted to: Polymer Degradation and Stability
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/14/2001
Publication Date: N/A
Citation: Interpretive Summary: Conventional wood adhesives typically contain phenol and formaldehyde in formulations. Both of these chemicals are considered toxic pollutants by the EPA. Recently, we developed an environmentally friendly wood adhesive from cornstarch chemically crosslinked with polyvinyl alcohol, a bio- degradable synethic polymer. Here, we further describe the characteristics sand optimization parameters of this adhesive. This research has a potential of creating new markets for surplus corn and having a positive impact on our environmental quality.
Technical Abstract: A wood adhesive was prepared from a natural renewable resource. The characteristics and optimization of starch and polyvinyl alcohol (PVOH)- based cross-linked adhesive suitable for wood-to-wood bonding in interior applications are described. The crosslinker, hexamethoxymethylmelamine (Cymel 323) produced effective cross-linking through a transetherification reaction between methoxy groups in Cymel 323 and hydroxyl groups in starch PVOH and wood, where hydroxyl groups replaced methoxy groups forming ether bonds with the crosslinker. Optimal viscosity of the adhesive was obtained at 27% solid content. Addition of latex in the formulation increased moisture resistance. The optimum cure temperature and cure time were 175 degrees C and 15 minutes. Wood samples conditioned at 93% RH for two months exhibited more than 95% failure in wood but little in adhesive joints. Scanning electron microscopy revealed no visible growth of fungi or other microorganisms on the adhesive after two months exposure of samples at 97% RH followed by one year at 50% RH.