Adhesive made from wood works in a standard glue gun

A by-product of the timber industry has been turned into a safe and reusable hot-gun glue that could replace solvent-based adhesives that are toxic to humans and the environment.

Ziwen Lv at Beijing Forestry University in China and colleagues created the glue from a xylan, a component of plant cell walls.

“Xylan is the material that holds cellulose together, although it is not itself a ‘glue’ in the traditional sense,” says Nick Aldred at the University of Essex, UK, who wasn’t involved in the study. “This work aims to re-purpose it as a glue.”

Lv’s team used sodium periodate and sodium borohydride to chemically modify the xylan, turning it into dialcohol xylan.

They say the resulting glue, which is extruded from a hot gun, has a bonding strength of 30 megapascals, surpassing conventional adhesives, including epoxy resin. The glue could also be reused by re-melting it, and maintained its original adhesion strength even after 10 cycles.

The team also constructed plywood, with three sheets of thin walnut timber held together by the xylan glue, and found it performed comparably with those made with phenol–formaldehyde resin adhesives.

But the xylan plywood had a significant drawback. After soaking in water for one hour, the glue dissolved, causing the layers to separate. The researchers didn’t respond to New Scientist’s requests for comment.

Jonathan Wilker at Purdue University, Indiana, says sustainable replacements are needed for all of the petroleum-based adhesives currently in use.

“[The] bonding performance [of the new glue] looked to be substantial, particularly with wood substrates,” says Wilker . “The life cycle assessment and water resistance results fell a bit short of incumbent glues now in use.”

“If it can be rolled out at scale in the plywood industry, it could be transformative,” says Aldred. “Plywood is one of the last remaining consumer products containing materials like phenol and formaldehyde, which were banned in products like cosmetics years ago.”