Scientists from the University of California, Berkeley have developed a method that could allow low value polyethylene bags to be turned into adhesives.
As the technique develops an adhesive that can bind plastic and metal (typically a difficult process), the adhesive could be used to integrate polyethylene and metal components in artificial hip sockets and knee implants.
But it could also be used to coat electrical wire in polyethylene providing greater durability, or to produce longer lasting composites that could be used in toys.
UC Berkeley Henry Rapoport chair in organic chemistry John Hartwig said: “The vision is that you would take a plastic bag that is of no value, and instead of throwing it away, where it ends up in landfill, you would turn it into something of a high value.
“You couldn’t take all of this recycled plastic – hundreds of billions of pounds of polyethylene are produced each year – and turn it into a material with adhesive properties, but if you take some fraction of that and turn it into something that is of high value, that can change the economics of turning the rest of it into something that is of lower value.”
The researchers worked on the basis of trying to upcycle the material rather than turn it into lower value fuels or lubricants.
By adding a chemical group to the polymer that makes it stick to metal, the original property of the polyethylene was retained.
Researchers also discovered that the modified polyethylene can even be painted with water-based latex, which normally doesn’t stick to this polymer either.
While the process is not yet economical for industrial use, Hartwig believes it can be improved and could be the starting point for adding other properties besides stickiness.
The success suggests that other catalysts could work with other types of plastics, such as polypropylene found in some plastic bottles to produce higher value products.