Machinery at municipal recycling facilities is often clogged with adhesives used on items such as can labels and cardboard boxes. However, this may no longer be the case in the near future due to the advent of new degradable adhesives.
In addition to disrupting recycling plant jobs, binder waste can clog a facility’s water supply and even end up as lower-quality recycled material.while other biodegradable adhesives Do While they exist, most of them lack the bond strength of their traditional counterparts.
To address these issues, a University of Surrey team led by Professor Joseph Keddie has developed an experimental new biodegradable adhesive described as “very similar to those used on commercial packaging tape”. Its key ingredient is a chemical additive called a thiol lactone, which makes up just 0.25 percent of its composition.
“Binders are made from networks of chain-like polymer molecules that are irreversibly linked together, which leads to the buildup of residue we see when recycling materials like glass and cardboard,” Caddy said. “Our additive creates what we call degradable thioester linkages in the polymer network and provides an innovative solution for making the recycling process residue-free.”
These linkages are completely degraded by the simple process of ammonolysis (chemical reaction with ammonia) or thiolysis (reaction with a molecule called coenzyme A). In laboratory tests using substrates such as glass, steel, plastic and paper, labels with the new adhesive peeled 10 times faster than labels with conventional adhesives.
Caddy and colleagues are now investigating the commercial viability of the adhesive and its environmental sustainability.Their research paper was recently published in the journal Applied Chemistry.
source: University of Surrey