Sticky residue in the form of adhesives applied to glass and other materials processed in recycling facilities can gum up the works, causing machinery malfunctions and other issues. A degradable adhesive has been formulated at the University of Surrey, U.K., to dissolve these obstacles to efficient recycling.

The new adhesive includes thionolactone, a chemical additive that allows the sticky material to be dissolved in the recycling process. Labels on jars and other products can also be detached up to 10 times faster compared to a non-degradable adhesive. The pressure-sensitive adhesive forms degradable thioesterA paper strip bearing the new adhesive (right) is removed from a metal substrate much quicker than one using a traditional adhesive (left). Source: University of Surrey connections to weaken the chain-like polymer molecules responsible for the strength and durability of commercial adhesives, enabling more efficient materials recycling.

Tests conducted on glass, steel, plastic and paper confirm that the additive dissolves the linked polymer networks, reduces the tack and peel strengths of conventional adhesives, and speeds label detachment from a substrate.

"While other degradable adhesives exist, there are none which resemble what is currently used industry-wide in their chemical make-up. We are proving it is possible to use similar adhesives and show that a simple additive has the potential to increase the quality of recycled materials such as glass and cardboard,” explains researcher Peter Roth.

"The next steps would be to look at the commercial viability of this additive, as well as look at the sustainability impact."

The research is published in the journal Angewandte Chemie.