Scientists make plastic more degradable under UV light

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Many plastics labeled as biodegradable are only compostable under industrial conditions, but scientists at the University of Bath have found a way to break them down using only UV light.

Due to growing public concern about plastic waste, PLA (polylactic acid), derived from the fermentation of sugars using lactic acid, is now widely used as a renewable and sustainable alternative to plastics derived from crude oil products, starting with disposable ones. 3D printing and packaging of glasses and tea bags.

It is often labeled as biodegradable, but has limited degradability in the natural environment, such as soil or seawater, and degrades only under conditions of high-temperature, high-humidity industrial composting, which can be obtained from household compost piles.

Scientists at the Center for Sustainable and Circular Technology (CSCT) at Bath University have now developed a way to make these plastics more degradable in the natural environment.

The group found that they can shape the degradability of plastic by incorporating different amounts of sugar molecules into the polymer.

Less than three percent of sugar-polymer units were found to be degraded by 40% in six hours after being exposed to UV light.

Most promisingly, the technology is compatible with existing plastics manufacturing processes, which means that the plastics industry can be quickly tested and approved.

published in Chemical communicationsresearchers hope that their findings will be used by the plastics industry in the future to help make plastic waste more degradable by the end of its product life.

The research was led by Dr. Antoine Buchard, Royal Society University Research Fellow and CSCT Polymer Chemistry Reader, who is assisted by the Royal Society.

He says, “A lot of plastics are labeled as biodegradable, but unfortunately that’s true if you throw it in the industrial waste composter; if it gets into household compost piles, it can last for years.

“Most PLA plastics are made up of long polymer chains, and it can be difficult to break down water and enzymes. Our research adds sugar to polymer chains by tying them all together through bonds that can be broken by UV light.

“This weakens the plastic, and when broken into smaller polymer chains, they become more sensitive to hydrolysis.

“This can make plastic much more biodegradable in the natural environment, such as in the ocean or in a pile of garden compost.

“Scientists have previously studied improving the degradability of PLAs in water – hydrolysis – but this is the first time anyone has studied the use of light.

“This strategy needs to be tested for real-life plastic objects and tested with sunlight, but we hope to use our technology in the future to make plastics that are strong when you’re using them, but which can be easily broken and reused and impossible to recycle.”


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More information:
Craig Hardy et al, UV degradation of poly (lactic acid) materials by copolymerization with cyclic xanthate derived from sugar, Chemical communications (2022). DOI: 10.1039 / D2CC01322C

Provided by Bath University

Mention: Scientists make plastic more degradable under UV light (2022, May 24) https://phys.org/news/2022-05-scientists-plastic-degradable-uv.html on May 24, 2022.

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