As part of its ambition to improve its environmental performance, the German carmaker Audi is exploring various different technologies for the recycling of plastic components from end-of-life vehicles. To that end, Audi is collaborating with partners from science and industry, including the Fraunhofer Institute, with whom the company has now embarked on a physical recycling pilot project.
Audi is seeking to gain experience with as many technologies as possible in order to establish material cycles for its production processes. Such cycles, according to the company, cut two ways: on the one hand, they reduce demand for renewable and raw nonrenewable materials; on the other materials derived through material cycles have a more favourable energy footprint.
Since different types of plastic require different sorting and recycling technologies, Audi is looking at several options at the same time: mechanical, chemical and, now, physical recycling.
By testing different approaches, optimal sustainable choices can be made - anything that does not make sense from an ecological point of view will be discontinued after the pilot phase, the company has said.
“Our focus is always on getting as many plastic contents as possible out of the car at the end of its life in order to be able to recycle them again,” explained Mike Herbig of Audi’s polymer team.
Some 200 kg of plastics and plastic composites are typically used in vehicles today. Bumpers, radiator grilles, various interior parts, as well as components in the drive system and air conditioning are all made of plastics.
In the automotive industry, stringent quality standards apply regarding the material used, both virgin and recycled. Crash safety, heat resistance, and resistance to substances such as organic solvents, oil, or hydraulic fluids must all be guaranteed, in addition to factors such as dimensional stability, quality, feel, appearance, and smell that must be maintained throughout the vehicle’s entire service life. Environmental requirements are also increasingly being taken into account.
“We only use a recycled material if the components made from it also meet the requirements, which is to say if the quality of the parts remains the same over their entire useful life,” said Herbig.
Mechanical recycling, while the first processing choice, can not always deliver the required quality or performance, nor is it a suitable solution for components made from composites or that incorporate various adhesives, coatings, and fillers. Working with the Karlsruhe Institute of Technology (KIT) and industry partners, Audi has also developed a chemical recycling method, where mixed plastic waste is processed into pyrolysis oil that can replace virgin crude as feedstock in the cracker. Components produced from the output of the cracker feature properties similar to those made from virgin material.