ABSTRACT
In recent years there has been resurgent interest in using biopolymers as sustainable and environmentally friendly ingredients in wood adhesive formulations. Among them, proteins and carbohydrates are the most commonly used. In this chapter, an overview is given of protein-based and carbohydrate-based wood adhesives. Included in the coverage are recent wood adhesives involving proteins, carbohydrates, glycoproteins, and protein/carbohydrate blends. A lot of interesting developments have been reported, particularly entailing modification reactions, use of additives, and blending. For example, soy protein is sometimes used as an ingredient for wood adhesives, and commercial wood adhesive products involving soy protein are available. It has been found that cottonseed protein added to soy protein can improve both its dry strength and its water resistance. In addition, cottonseed- and soy-protein based adhesives have been formulated with xylan, starch, or celluloses to determine the influence of polysaccharide fillers on protein-based adhesive properties. In some cases, adhesive strength is retained even when the cottonseed or soy protein is mixed with up to 75% polysaccharide.
