Breakthrough made in sustainable recycling of acrylic

Scaling the process beyond the lab and building the processes needed to support it remain key barriers to real-world impact, says independent authority

A more environmentally friendly way to recycle acrylic – one of the world’s most widely used plastics – has been developed by researchers at the University of Bath.

Often sold under the brand names Perspex and Plexiglas, acrylic is made from transparent thermoplastic polymethyl methacrylate (PMMA). Shredding has often been used to form pellets for reuse but this can lead to a decline in quality, meaning the recycled material becomes unsuitable for use as screens or spectacles.

Instead, recent industry focus has been on pyrolysis – heating the PMMA to above 350°C in the absence of oxygen to turn the plastic back into its monomer building blocks to be made from scratch again, in pristine quality. However, this is energy-intensive and easily contaminated by other plastics. 

A new process, developed by the team at Bath, uses UV light, again under oxygen-free conditions, to chemically break down the PMMA. Crucially, the chemistry works at 120-180°C, lowering the energy input needed, improving both environmental performance and commercial scalability.

Dr Jon Husband, ISCC Research Fellow in Sustainable Chemical Technologies at the University, said: “Current solutions require high temperatures, which is problematic in countries where energy costs are high. It also produces unwanted degradation pathways, especially of contamination, which reduces the purity and overall quality of the resulting depolymerisation product.

“This new process operates at approximately 150°C and utilises light as an energy input. This minimises side reactions and gives us the potential to target depolymerisation of dirtier plastic wastes. Together, these factors indicate that the technology has strong potential to be both significantly greener and more cost-effective than existing technology.”

Work is now under way to scale the technology and expand its application to other plastic streams with hard-to-break-down carbon backbones. Dr Husband said: “Industry partners are already engaged in the development of the technology.”

“The ability to recover high-quality recyclates at significantly lower temperatures addresses two of the biggest barriers…”

Richard Cham, Technical Manager at RECOUP, an independent authority on plastic recycling, described the research as “genuinely exciting”. He said: “The ability to recover high-quality recyclates at significantly lower temperatures addresses two of the biggest barriers to making chemical recycling commercially viable: energy cost and output quality. 

“For a material like PMMA, which has historically been difficult to recycle at scale, this kind of closed-loop approach is exactly what the sector needs to be exploring. That said, the process is currently at laboratory scale, and the path from grams to tonnes is rarely straightforward, and often where these projects fail without sufficient support. The real challenge now will be scaling the technology and developing the collection infrastructure to feed it.”

The team from Bath will be competing with researchers around the world, including those at ETH Zurich who are testing UV-activated chlorinated solvents to drive depolymerisation. The Bath team uses more sustainable solvents, but the challenge remains to recycle at scale.