Recycled plastic used to make graphene for Ford’s enhanced foam

Houston, Texas – A team led by James Tour at Rice University has developed a flash Joule heating process to turn plastic parts from end-of-life vehicles into graphene. The material was sent back to Ford, and incorporated into its graphene-infused polyurethane foam for use in new cars. This enhanced foam has been used in Ford vehicles since 2018, because of its noise reduction and heat resistance properties.

The amount of plastic used in vehicles is increasing as manufacturers chase weight reduction and improved fuel economy, but this is posing greater problems for the manufacturers in the light of end-of-life regulations for vehicles. ‘In Europe, cars come back to the manufacturer, which is allowed to landfill only 5% of a vehicle,’ Tour said. ‘That means they must recycle 95%, and it’s just overwhelming to them.’

Much of the mixed plastic waste will be incinerated, according to Deborah Mielewski, technical fellow at Ford and an author on the paper. With the US shredding more than 10 million vehicles a year, this makes for a large amount of waste. ‘We have hundreds of different combinations of plastic resin, filler and reinforcements on vehicles that make the materials impossible to separate,’ she said.

And this is why Ford approached the Rice team, having become aware of its plastic-to-graphene process. Essentially, mixed ground plastic is blasted with a high voltage, and the sudden, intense heat of more than 2500°C vaporises the other elements, leaving behind turbostratic graphene. No solvents are required, and the energy requirements are not significant.

Ford sent the Rice team about 5kg of muddy and wet mixed plastic waste from a vehicle shredding facility. ‘We flashed it, we sent the graphene back to Ford, they put it into new foam composites and it did everything it was supposed to do,’ Tour said. ‘Then they sent us the new composites and we flashed those and turned them back into graphene. It’s a great example of circular recycling.’

To test its effectiveness on end-of-life mixed plastic, a mixture of shredded plastic bumpers, gaskets, carpets, mats, seating and door casings from end-of-life F-150 trucks was ground into a fine powder, with no washing or pre-sorting. It was first flashed for 10–16s under low current to make a highly carbonised plastic, accounting for about 30% of the initial mass; the rest was out-gassed or recovered as hydrocarbon-rich waxes and oils.

The carbonised plastic was then flashed under a higher current, with 85% converted to graphene and the remainder outgassed as hydrogen, oxygen, chlorine, silicon and trace metal impurities. A lifecycle analysis showed a substantial reduction in energy, greenhouse gas emissions and water use compared to other methods for making graphene.

The work has been published in the journal Communications Engineering.