Chromatographic analysis of the reaction of soy flour with formaldehyde and phenol for wood adhesives

Abstract

The desire to make more biobased and lower-cost bonded wood products has led to an interest in replacing some phenol and formaldehyde in wood adhesives with soybean flour. Improved knowledge of the soy protein properties is needed to relate resin chemistry to resin performance before and after wood bonding. To expose the soy protein’s functional groups, it needs to be disrupted, with minimal hydrolysis, to maximize its incorporation into the final polymerized adhesive lattice. The best conditions for alkali soy protein disruption were to maintain the temperature below 100°C and react the soy flour with sodium hydroxide at pH 9–12 for about 1 hour. A gel permeation chromatography procedure was optimized to determine conditions for selectively breaking down the high molecular weight soy protein fragments that contribute to high adhesive viscosity. This method and extraction data were used to evaluate the reaction of the disrupted soy flour protein with formaldehyde and phenol to provide a stable adhesive. The results were used to develop more economical adhesives that are ideally suited for the face section of oriented strandboard.

Citation

Lorenz, Linda F.; Frihart, Charles R.; Wescott, James M. 2007. Chromatographic analysis of the reaction of soy flour with formaldehyde and phenol for wood adhesives. Journal of the American Oil Chemists'' Society. Vol. 84, no. 8 (Aug. 2007): pages 769-776.