On August 8th, 2023, a rapid publication in the journal Nature reported the latest research findings by Professor Shuai Li's team from the College of Material Engineering at Fujian Agriculture and Forestry University. The team has successfully overcome the technical challenges of traditional lignin-based wood adhesives, including complex preparation processes, high costs, and poor performance. They have utilized high-activity lignin to develop a new green lignin-based wood adhesive with excellent bonding properties, which shows promise as an ideal alternative to petrochemical-based bulk adhesives.
Engineered wood composites, such as particle boards, are widely used in various fields including construction and interior decoration. China's annual production of engineered wood surpasses 300 million cubic meters, ranking first in the world. Currently, the commonly used adhesives for these wood composites are urea-formaldehyde and phenol-formaldehyde resins, which primarily rely on petrochemical resources and often suffer from formaldehyde emissions. To reduce dependence on fossil resources, the industry has turned its attention to utilizing lignin from renewable lignocellulosic biomass as a partial substitute for phenol, leading to the development of lignin-phenol-formaldehyde resins. However, industrial lignin exhibits severe condensation and low reactivity during the separation process, resulting in adhesives with inferior bonding performance, darker color, higher cost, and an inability to completely overcome formaldehyde emissions. Consequently, there is a growing interest in the academic and industrial communities to develop low-cost, high-performance, and non-toxic wood adhesives using green and low-carbon biomaterials.
Inspired by lignin's ability to bind cellulose and hemicellulose in lignocellulosic biomass in a glue-like manner, Professor Shuai Li and his team extracted highly active lignin from wood and agricultural residues to create a novel green lignin-based wood adhesive. With this adhesive, they successfully produced high-quality plywood within a broad temperature range of 100 to 190 degrees Celsius, offering advantages such as green synthesis, simple processing, excellent performance, and low cost.
Microscopic interface characterization revealed that the adhesion mechanism of the lignin-based wood adhesive primarily involves lignin softening and the penetration and filling of softened lignin into intercellular spaces such as vessels. Using techniques such as two-dimensional nuclear magnetic resonance and micro-infrared spectroscopy, it was found that the lignin in the adhesive undergoes in-situ self-crosslinking and forms crosslinks with native lignin in plant cell walls. Overall, the lignin-based adhesive achieves both physical and chemical bonding at the interface, enabling the efficient production of green, low-carbon wood products.
This expanded article provides a more detailed and academic description of the development of the new lignin-based wood adhesive. The research conducted by Professor Shuai Li's team offers valuable insights into the preparation method and bonding mechanism of this green adhesive. It paves the way for the application of lignin-based wood adhesives in the engineered wood industry. The findings hold significant academic value and practical application prospects, contributing to the advancement of lignin-based adhesive technology and the realization of sustainable development goals.