Circular Economy

Upcycling to fibre-reinforced plastic

A new recycling process to transform polyethylene terephthalate (PET) plastic into a more valuable material with better properties has been developed by US researchers, who aim for the new technique to help with the serious and urgent problem of ever-increasing amounts of plastic waste in our oceans and the environment.

The process combines PET plastic with renewable sources, such as waste plant biomass, to create a type of fibre-reinforced plastic (FRP) that is longer lasting, more versatile and more valuable, while also being more energy-efficient to produce than recycled PET or conventional FRPs.

While work on the scalability of this process is still ongoing, the research team from the Department of Energy’s National Renewable Energy Laboratory (NREL) in Denver, Colorado, is confident its approach can overcome one of the biggest stumbling blocks to mass recycling, which is the economics.

“Most PET recycling today is mechanical and results in materials that have a lower value than the virgin plastic, so it is actually downcycling,” said Gregg Beckham, NREL study leader.

“Our process takes reclaimed PET and combines it with non-food plant-based building blocks to make materials that are much more valuable, and hence upcycled, have different functions and a longer life than the starting single-use plastic.

“Indeed, the FRP produced could be used in car parts, wind turbine blades, surfboards and snowboards.”

In a paper published in the Journal Joule, the researchers report that by combining PET with sustainably-sourced, bio-based molecules they produced two types of FRPs that are two to three times more valuable than the original PET.

Their analysis also suggests these composite products would require 57 per cent less energy to produce than standard reclaimed PET, using the current recycling process, and would emit 40 per cent fewer greenhouse gases than current petroleum-based FRPs.

“Supply-chain energy calculations reveal that this strategy for plastics upcycling could save significant total manufacture energy, mainly from savings in associated energy from petroleum feedstocks and could also reduce greenhouse gas emissions,” the researchers wrote.

“Overall, this approach provides an economic incentive for plastics recycling and renewable feedstock use through the creation of long-lifetime, performance-advantaged materials.

“The next step is to produce materials that can themselves be recycled. The current composites can last years, even decades, but are not necessarily recyclable in the end.”