An overview of different types and potential of bio-based adhesives used for wood products

Abstract

Bio-based adhesives have shown promise in the engineered wood products industry, and there is a substantial growth of research on bio-based bonding agents. Wood is a renewable resource, and most of the engineered wood products are synthetic adhesive-bonded composites and laminates. Environmental concerns exist for the use of adhesives made from fossil fuels lowering the bio-content of the bonded wood products. Bio-based adhesives are getting more attention since they are environmentally friendly green products without any adverse effects on the environment. However, there is a remaining challenge for the industry to make them more effective than synthetic ones in terms of their mechanical properties and long-term durability. These adhesives, with different components such as cellulose, proteins, lignins, and tannins are adhesives which exhibit great potential for the bonding of specially engineered wood products. The modification of bio-based adhesives with different dispersing agents and cross-linkers can improve their strength and water resistance properties to compete with synthetic adhesives. The blending of proteins and carbohydrates can yield good bio-adhesives with acceptable adhesive properties. All these improvements of bio-based adhesives help us move towards ‘sustainable’ products where clean synthesis, biomass and water-based processing are highly desirable. Based on studies conducted in recent decades, the objective of this article is to review the production processes of adhesives from different bio-resources, their necessary modification for improving properties and their utilization in the wood-based industries. Finding the research gaps would also help to hasten the research activities for applying these bio-based adhesives at the industrial scale.