Researchers at the University of Bath have developed a new method for repeatedly chemically recycling acrylic plastic without reducing quality.
In contrast to conventional mechanical recycling, the new method uses lower temperatures and sustainable solvents without losing material quality, which the researchers say allows the plastic to be recycled many times over with ‘minimal environmental impact’.
Acrylic, often sold under brand names such as Perspex and Plexiglas, is made from the transparent thermoplastic polymethyl methacrylate (PMMA).
The material is used in a wide range of applications, including automotive components, screens and construction materials.
Currently, the researchers can recycle a few grams of real plastic waste at a time, and work is ongoing to improve efficiency and scale the process.
Commenting on the announcement, Dr Jon Husband, ISCC Research Fellow, who co-led the research, said: “With current methods for recycling both energy intensive and inefficient, the demand for cleaner, more efficient recycling technologies has never been greater.”
“Plastic recycling can be tough to make economically feasible, due to issues around high energy costs and low-quality product; this work directly addresses both of these issues.”
Mechanical recycling is the most common method for recycling acrylic and can often involve shredding or melting the plastic to reform pellets for new uses.
However, this can lead to discolouration and a gradual decline in quality, meaning the recycled material can no longer be used for glass-like applications, such as screens or spectacles.
The new process developed by the team at Bath uses UV light under oxygen-free conditions to chemically break down consumer-grade PMMA plastic into its original monomer building blocks.
The new approach also works at a lower temperature than the conventional method, which means the energy input required is significantly lower.
The researchers say the new process delivers over 95% conversion of the plastic and yields more than 70% monomer, which can then be purified and repolymerised into ‘as new’ materials.
The work, published in Nature Communications, was led by Dr Jon Husband and Dr Simon Freakley from the University’s Institute of Sustainability and Climate Change (ISCC) and co-authored by the Innovation Centre for Applied Sustainable Technologies (iCAST) Director Professor Matthew Davidson.
