Upgrading and recycling of polyethylene: After modification, it can be used as an adhesive to firmly adhere to metal

Recently, researchers at the University of California, Berkeley, have invented a new chemical process that can recycle waste plastic bags (mainly polyethylene PE) and convert them into more valuable adhesives to upgrade polyethylene.

According to reports, John Hartwig, professor of organic chemistry at UC Berkeley and leader of the research team, and his colleagues used a catalyst based on ruthenium (with a gold ball in the middle) to add specific chemical group (in this case OH (red)), thus forming an oxidized polyethylene

In 11 attempts, researcher Katerina Malollari had difficulty separating water-based latex paint from oxidized polyethylene (Ox-LDPE), which had previously been difficult to adhere to common plastics

"There are typically 2,000 to 10,000 carbon atoms in a polyethylene chain, and each carbon atom has two hydrogen atoms - in effect, it's a sea of ​​CH2 groups called methylene groups

Considering that solid recycled plastic needs to be melted, it is required that the catalyst used for polyethylene recycling modification can work in high temperature and non-polar solvent so as to be mixed with non-polar polyethylene

Hartwig and postdoctoral associate Liye Chen investigated a ruthenium-based catalyst (polyfluororuthenium porphyrin) that meets these requirements and enables the addition of OH groups to the polymer chain without the highly reactive hydroxyl groups allowing the polymerization chain breakage

The researchers found that catalysis chemically changed less than 10 percent of the polymer, but greatly enhanced its ability to adhere to other surfaces

Professor Hartwig said the process is not yet economical enough for industry, but it can be improved