Single-use plastics cause plastic pollution, a problem that affects rivers, lakes, and oceans. To address this concern, researchers from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) developed a recycling process that turns various materials made of polyethylene terephthalate (PET) into other useful products that will last longer.
NREL’s research was published in the journal Joule.
What is polyethylene terephthalate (PET)?
Polyethylene terephthalate (PET) is a plastic resin. The polymer is created by combining two monomers, modified ethylene glycol and purified terephthalic acid. PET was first synthesized in North America by Dupont chemists in the 1940s.
This common polyester material is lightweight yet strong. PET is also shatterproof and resistant to water, which makes it a prized material among manufacturers.
Bottles and containers made from PET are labeled with the #1 code on or near the bottom. PET is often used to package various products such as:
- Baked goods
- Frozen foods
- Household cleaners
- Peanut butter
- Salad dressings
PET is sturdy, thermostable, and transparent, which makes it a suitable material for packaging. Additionally, PET is inexpensive, resealable, and recyclable.
Upcycling plastic bottles
Although PET is recyclable, the majority of the 26 million tons of PET-based packaging produced annually is sent to landfills or dumped elsewhere. PET takes at least hundreds of years to biodegrade.
The recycling process for PET could also use some improvement. Since reclaimed PET has a lower value than the original, it can only be repurposed once or twice.
Thankfully, the new recycling process developed by NREL can turn carpet, clothing, and single-use beverage bottles made from PET into longer-lasting, more valuable items. This process can help protect oceans from plastic waste by revamping the recycled plastics market.
Gregg Beckham, the study’s senior author and a Senior Research Fellow at NREL, explained that standard PET recycling today involves “downcycling.” But with the new process the research team developed, PET can soon be “upcycled” into long-lifetime, high-value composite materials similar to those used to make car parts, snowboards, surfboards, or even wind turbine blades.
For the study, the researchers combined reclaimed PET with building blocks acquired from renewable sources like waste plant biomass. This produced two types of fiber-reinforced plastics (FRPs). These FRPs are at least two to three times more valuable than the original PET.
The researchers foresee that the composite product would need 57 percent less energy to produce, unlike reclaimed PET made using the current recycling process. It would also emit 40 percent fewer greenhouse gases than standard petroleum-based FRPs, which is a significant improvement.
Beckham shared that their goal is to develop technologies that can help incentivize the economics of PET reclamation. They also hope to develop “second-life” upcycling technologies that will make single-use waste plastic valuable to reclaim.
Achieving this goal could be the key to eliminating plastic waste from the world’s oceans and landfills. (Related: New material made from recycled plastic bottles could help reduce water pollution.)
The future of upcycled PET products
The plan sounds good on paper, but the researchers have their work cut out for them before they can implement the recycling process outside the laboratory.
The researchers plan on further analyzing the properties of the composite materials produced when PET is combined with the plant-based monomers. They also plan to test the process for scalability to confirm if it can work in a manufacturing setting.
Additionally, the research team aims to develop composites that can be recycled on their own. While the current composites can last years or decades, they are not necessarily recyclable in the end. The NREL team has made plans to develop similar technologies for recycling different kinds of materials.
Nicholas Rorrer, one of the authors and an engineer at NREL, says that PET production is currently accomplished on a larger scale than composites manufacturing. This means that the researchers will need to develop more upcycling solutions to make a long-lasting global impact on plastics reclamation using technologies like the one proposed in their study.
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