IIT Madras, Columbia and Colorado varsity scientists develop sustainable plastic recycling technique

This is a technique by which different types of plastics can be combined to produce new composite plastics that are not only strong but can also be reprocessed and recycled. This could potentially revolutionise the plastics recycling industry.

New Delhi: Researchers at IIT Madras, Columbia University and Colorado State University in the US have developed a technique to merge diverse plastics into strong and recyclable materials.

According to officials, this multi-institutional team has developed a technique by which different types of plastics can be combined to produce new composite plastics that are not only strong but can also be reprocessed and recycled.

The findings of this research, which could potentially revolutionise the plastics recycling industry, have been published in the prestigious peer-reviewed journal Nature.

Traditional plastics recycling methods have some issues due to the immiscibility of diverse polymers. The group of researchers employed a specially designed universal dynamic crosslinker (UDC) to successfully blend usually incompatible plastics.

The research not only addresses the plastic waste crisis but also holds the promise of transforming the way society perceives and manages plastic recycling, officials said.

By providing a practical solution to the challenge of mixed plastics, this innovative technique represents a significant stride towards a more sustainable future, they said.

Tarak Patra, Assistant Professor, Department of Chemical Engineering, IIT Madras told PTI, "Although India’s plastic recycling rate of 13 per cent exceeds the global average of 9 per cent, there are technical hurdles hindering further progress in plastic recycling. Plastic waste is made of many different kinds of polymers and these polymers do not mix easily."

"Thus, recycling currently involves a lot of separation, which is time-consuming and inefficient. If all the plastics can be made compatible, they can be treated as one unit without the need for segregation," Patra said.

Patra explained further that to recycle plastic mixtures effectively, we must ensure that different plastics can blend together without losing their unique properties.

"This is akin to mixing oil and water, which naturally repel each other. However, through a process called 'compatibilisation', we can make them blend without compromising their individual characteristics," he said.

Sanat K Kumar, Professor of Chemical Engineering, Columbia University, said the basic concept is that if you look at many waste plastic materials, they are typically many different kinds of plastic.

"The problem is that if you try to reprocess this mixed plastic waste, it tends to be immiscible, meaning the material formed tends to be mechanically weak. So, what we have done is to come up with a process by which even though they are immiscible, we can stitch the interface between immiscible phases and make the mechanical strength good so that we can take a mixed plastic waste, recycle it and get a product that is useful," he told PTI.

Eugene Chen, Professor at Department of Chemistry, Colorado State University, however, said the key barrier in the technique is cost.

"This new strategy could help achieve the ultimate goal of reusing mixed plastic waste over multiple use cycles. A key barrier is cost; we are talking about millions of tons of plastic waste, and you have to consider how many of these dynamic crosslinkers you need, although we currently need only less than 5 per cent of the weight of the plastics in our upcycling process.

"Like many fundamental discoveries made in history, practical obstacles exist at the very beginning, but we are very excited about future potential," Chen said.