Scientists in China have developed a natural, non-toxic adhesive for potential use in the creation of composite wood products found in our furniture, décor, and flooring.
Flexible plywood panels are produced by gluing thin layers of wood together and curing them under high pressures and temperatures. The glues used in this process have historically been chosen for their ability to bond strongly with wood but tend to contain formaldehyde. Their use has raised concerns about harmful emissions being released into the air.
Past research has demonstrated how a glucose and citric acid solution can effectively act as a strong, natural, water-resistant wood glue. However, it was previously thought a zinc chloride catalyst was necessary to reduce energy consumption during the curing process, which in turn weakens the adhesive effects.
PhD student Hong Lei of Southwest Forestry University in Kunming was part of a team of researchers that set out to discover whether glucose and citric acid alone could produce a strong adhesive while delivering a more energy efficient curing process.
The team created solutions of glucose with varying amounts of citric acid, before applying them to poplar veneers to produce plywood sheets. Tested at a temperature of 392 °F and under pressures greater than 101 psi, all the plywood samples only broke along the wood fibers and not at the glued seams, satisfying the standard requirements for plywood in China.
Based on their findings, the research team is hopeful that citric acid and glucose adhesives could become commonplace in the production of plywood in the future, yielding benefits for health and the environment.
Source: Phys.org
