Researchers develop new chemical process to break down waste rubber

Chapel Hill, North Carolina – Researchers at the University of North Carolina – Chapel Hill have developed a chemical process to break down waste rubber into precursors for epoxy resins.

The study, led by UNC researcher Aleksandr Zhukhovitskiy, uses “C–H amination and a polymer rearrangement strategy” to transform discarded rubber into "valuable" feedstock materials.

Funded by the US department of energy, the project introduces “a sulphur diimide reagent” that enables the installation of amine groups at specific locations in the polymer chains.

This step is crucial because it sets the stage for the subsequent backbone rearrangement, explained a UNC report issued 26 March.

The chemical reaction “reorganises the polymer backbone”, breaking down C-C bonds of rubber materials, such as polybutadiene- and polyisoprene-based rubbers.

The conversion process yields soluble amine-functionalised poly-diene materials, which can then be used to produce epoxy resins.

“By harnessing the power of C–H amination and backbone rearrangement, this method provides a new pathway to transforming post-consumer rubber into high-value materials,” said co-author Sydney Towell.

In a test with a model polymer, the researchers broke the material down significantly: reducing its molecular weight from 58,100g/mol to about 400g/mol.

Applied to used rubber, the method broke the rubber down “completely” in six hours, turning it into “a soluble material with amine groups.”

According to the research team, the efficiency of this method is particularly striking when compared to traditional recycling techniques, which often require extreme temperatures or expensive catalysts.

The researchers achieved their results under relatively mild conditions (35-50°C) in aqueous media, making the process more environmentally friendly and cost-effective.

Usually made from petroleum-based chemicals, epoxy resins are widely used in industries for adhesives, coatings, and composites.