UTo save weight, car manufacturers are using more and more components made from engineering plastics. The requirements are high and often cannot be met with single-origin material. In addition, they often contain flame retardants based on chlorine or bromine. The result: material recycling is not possible. All that remains is burning.
Researchers at the Karlsruhe Institute of Technology (KIT) have therefore developed a concept with which body and engine parts, dashboards, steering wheels, armrests and other components can be broken down into their component parts. This takes place in a pyrolysis reactor, in which the shredded components are heated in the absence of air. The networking of the plastics breaks apart. Combustible coke is formed, a gas that contains monomers from which simple plastics can be made, and a pyrolysis oil that is equivalent to natural petroleum. Ten percent of the energy content of the car components to be recycled is required for heating. Part of this is supplied by the coke that is produced.
Composite plastics, which consist of several types, can also be broken down into their constituent parts with the help of solvents. Researchers at the University of Wisconsin-Madison have developed a method to do this. So far, however, this has only worked with transparent packaging films for food and medical devices. Solvents for high-performance plastics do not yet exist.
The car manufacturer Audi wants to test the recycling process in a pilot project. For this purpose, plastic components such as fuel tanks, wheel covers and radiator grilles are shredded and converted in a pyrolysis reactor. If it is possible to manufacture components from the pyrolysis oil that meet the high requirements of the automotive industry, then crude oil consumption should be reduced step by step.
Audi is already further with recycling in another area, with bottles made of polyethylene terephthalate (PET). The latest version of the A3 model is fitted with seat covers that are largely made from recycled PET.