• Tamsin

How to make plastic recycling sustainable

Updated: Aug 4

Let’s be honest. Plastic recycling is failing; it’s why most plant-hoarding bamboo straw-using people are fierce advocates of the ‘Reduce and Reuse’ mantra. Only 9% of plastic produced is recycled. That means that the vast majority is accumulating in landfills or sloughing off in the natural environment as litter.

But we live in a plastic society; from packaging to transportation, from medical devices to electronics, plastic is omnipresent. To avoid plastics entirely, you would have to resign to live the rest of your life as a hermit. And not many are willing to make such a sacrifice for the cause, myself included. If lockdown has taught us anything, it’s the importance of social interactions.

That leaves us with recycling. However, plastic recycling is fraught with challenges. From mixed polymers to chemicals additives, plastics are one of the most difficult materials to recycle. Most recycling centres operate on a mechanical recycling process (see here for a great infographic) where pressing or grinding plastic causes it to lose its original quality. It’s why plastics that are successfully recycled can only undergo this process once or twice before being discarded. Far from the ideal closed loop needed for a circular economy.

There is a silver lining. An alternative to mechanical recycling is chemical recycling which consists of breaking down the material to individual building blocks that can then be used to create new plastics. However, the polymer chains of polyethylene, one of the most used plastic, are extremely stable and require being heated to over 600° Celsius to break the chemical bonds. Not exactly energy-efficient is it?

That’s why the work done by Mecking and colleagues is so exciting. The team of researchers have developed a novel model to chemically-recycle polyethylene. A method so efficient that it achieves a 96% recovery rate. The process involves detecting polymers that have weaker intramolecular forces and are thus easier to break away from the chain. The process only requires temperatures of only about 120° Celsius. The team tested their method on bioplastic polyethylene and mixed plastics commonly found in waste streams.

"Recyclability is an important aspect for future technologies based on plastics. Re-utilizing such valuable materials as efficiently as possible makes sense. With our research we want to contribute to making chemical recycling of plastics more sustainable and effective," Stefan Mecking resumes.
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