Synthesis of novel sustainable polymers does not address the issue of increasing plastic waste arising from plastics now in circulation. Recycling of these plastics is the obvious solution, but current recycling technologies suffer from disadvantages such as cost, degradation of mechanical properties, and detrimental environmental impact. The GML has expanded its research to combat poor recycling technologies through study of degradation processes and innovation of new recycling tools. Our recycling projects focus on developing these new and existing techniques to improve the recycling process of different polymeric materials. This covers responsive recycling processes, in-depth recycling analysis, creation of bespoke additives, chemical recycling, and introduction of new recyclate detection systems. We work with a variety of polymeric systems with focus on HDPE, PP, PET and PET-G.
Mechanical recycling causes severe degradation of polymeric materials through thermo-oxidative and mechanical reactions. As part of our work, we look at how these degradation reactions affect the properties of recyclate through thermal, mechanical, and rheological characterisation. Understanding these reaction mechanisms allows us to investigate how degradation can be negated or controlled through the correct extrusion techniques and inclusion of additives. By improving recyclate quality, we aim to contribute to the circulation of high value plastics, preventing excess landfilling of low-quality plastic wastes.
Once plastics are no longer suitable for mechanical recycling, they can be sent for depolymerisation into re-polymerisable monomers. Chemical recycling offers a way to produce a circular product – product recycling system with retained high material value. Our research explores new methods for depolymerisation of enhanced polymers such as PET and PET-G to provide novel, green and reproducible routes to useful monomers.
Our work also focuses on methods to mark recycled content and the number of recycles a plastic has been subject to. We can use bathochromic shifts resulting from aggregation of fluorescent dyes to mark the recycled content of common plastics as an answer to the UK’s 2022 plastic packaging tax. By promoting use of fluorescently marked recyclate, we hope to discourage landfilling, reduce greenhouse gas emissions, and improve the reliability of recyclate detection.
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