Image: © Andrii Zastrozhnov/Stock.adobe.com
Both in Ireland and abroad, teams of scientists are finding ways to turn an overload of plastic waste into a truly renewable resource.
The message is abundantly clear these days to anyone who turns on a TV or browses social media: our planet is teeming with plastic waste. Whether it’s forming nation-sized islands of waste in our oceans or filling the sides of our roads where it will last for centuries, something needs to be done.
For example, by 2050 scientists believe that there will be more plastic by weight in the world’s oceans than fish.
While campaigners such as David Attenborough have shone a bright spotlight on this issue and have brought on a major change in attitude to plastic in many parts of the world, this still might not be enough. Certainly, a change in attitude from the general public could stem the tide, but for every waste-conscious person there’s a company dumping tonnes of single-use plastics for the sake of cost and convenience.
This doesn’t mean there is no hope, as one surefire way to get someone to change their ways is if it can be financially beneficial for them to not dump it.
Researchers of the world, unite!
This has spurred on researchers from across the globe who are now finding ways to make one of the most common plastics entirely recyclable. Not only that, but it would turn plastic waste into a renewable source, making the collection of plastic waste more financially attractive to those less environmentally conscious.
One such recycling project is underway at the University of Limerick’s (UL) Irish Composites Centre (IComp), where a team led by Dr Walter Stanley is turning polyethylene terephthalate (PET) plastic into sheets that could be used for car parts.
PET is perhaps one of the most familiar to consumers as it is used in many plastic household items, particularly plastic bottles. With the backing of Enterprise Ireland and the Environmental Protection Agency, the team’s patent-pending technology turns PET into a high-tensile fibre that can then be woven into a fabric.
This fabric has the potential to be used in the production of high-performance, recyclable composite parts for the automobile and agricultural vehicle industries.
From left: Dr Walter Stanley, Dr Subramani Pichandi and Rachel Kennedy of IComp at the Bernal Institute, University of Limerick. Image: IComp
‘Cradle to grave to cradle again’
Speaking with Siliconrepublic.com, Stanley said as part of the project, called ‘SerPET’, companies have provided chips of PET that can be broken down in his lab. Using the team’s technology, 100pc of the produced material is made from this recycled PET, with zero wastage.
Touching again on the financial realities of recycling, Stanley said: “We know that while PET is a fantastic material, it is a scourge because of the lack of recycling. It’s financially attractive for people to recycle this material into a higher-end product.”
Continuing, he added: “At the end of the day, the material that we can produce is fully recyclable at the end of its life, so it’s cradle to grave to cradle again.”
One area where he sees this technology being of enormous benefit is in the production of wind turbine blades, which are not currently recyclable.
“We talk about wind turbine blades that are invariably between 60 metres and 70 metres in length made from glass fibre and polyester resin,” Stanley said. “That isn’t recyclable at all. People say it’s green energy, but at the end of the day we’ve got huge blades that go into the landfill.”
While Stanley and the rest of his team are in the midst of seeking larger industry partners, one giant of industry is already working on its own plastic-eating technology that takes a different approach to recycling PET.
VolCat ready to pounce
Developed by IBM researchers, a new process called Volatile Catalyst (VolCat) digests polyesters into a substance that can be fed directly back into plastic manufacturing machines in order to make new products.
The process begins by heating PET and ethylene glycol in a reactor with a catalyst and, after depolymerisation is complete, the catalyst is recovered by distillation from the reactor using the heat of reaction. The remaining solution is filtered, purified and then cooled, with the solid monomer product recovered by filtration.
The recovered liquid and catalyst are reintroduced into the reactor to create reusable PET with zero waste. The researchers believe VolCat could soon be used at recycling and polyester manufacturing plants across the globe.
Additionally, it solves another environmental problem found in polyester reactors, that being their need for petroleum. In five years’ time, the researchers said, this need for fossil fuels could be eliminated by attaching a VolCat system to existing assembly lines.
Speaking of one of its biggest advantages over existing systems, IBM Research’s senior manager of chemistry and materials, Bob Allen, said that unlike traditional methods, VolCat does away with the need to wash and sort the waste plastic because “the molecule does the sorting”.
“Innovation is really required to move the industry from where we are today to something that takes advantage of this waste as a natural resource,” Allen said in an interview with Plastics Today. “We feel strongly that material and process innovation is key to helping the world with the waste plastic issue. We want to move the VolCat process out of the lab and into the world as quickly as we can.”
