Lignin‐Based Adhesives

The increasing concerns about the depletion of fossil fuels and the environment drive the efforts to search renewable alternative chemicals for sustainable material synthesis. Woody biomass is the most abundant biomass on earth, of which lignin is the second largest component after cellulose. As the most abundant natural phenolic polymer, lignin is a potential substitute of phenol for phenolic resin adhesives synthesis. This chapter focuses on adhesives that were synthesized with renewable lignin. We summarize the sources of industrial lignins and the effects of separation processes on lignin structure and reactivity. The methods for pretreating or modifying technical lignins to improve the reactivity of technical lignins for bio-based adhesives synthesis are discussed and the application performances of adhesives synthesized from modified technical lignins are reviewed. Finally, we present the challenges and prospects of developing adhesives with high lignin substitution ratios and high performances.