After being used, plastics end up in a mix of compounds within the recycling chain. By chemically recycling these plastics through depolymerisation and dissolution, polymers can be separated from additives such as flame retardants. TNO is developing technologies that enable this without the use of destructive thermochemical methods. We monitor these processes with sensors developed in-house.
When it comes to the best solution for sustainability, a waste management and recycling company will initially opt for plastic-to-plastic recycling, i.e. mechanical recycling. If this is not possible, other technologies are available to treat plastics. An extra chemical recycling step splits the different (mixtures of) polymers into components that can be recycled.
Through the use of a solvent that dissolves one polymer or additive and not another, it is possible to separate different polymers before proceeding to the next stage of treatment. However, because the combination of plastics and additives is always different, TNO is constantly looking for a unique combination of solvent and polymer type.
TNO is developing technologies to chemically recycle polymer additives as well as building sensors that monitor the purity of the process. This process must also be continuous, inexpensive and efficient, operate on a large scale, deal with variations in raw materials, deliver consistent quality and so on.
An example of TNO’s process development is the European consortium PLAST2bCLEANED, established in order to reclaim additives, such as brominated and antimony-containing flame retardants, from high-quality engineering plastics in electronics. Initially set up at a laboratory and pilot scale, we’re now investigating how we can work alongside partners such as Electrolux and Fraunhofer to further develop the process to a demonstration scale.
The value of additives makes recovery very worthwhile from an economic perspective. Moreover, additives can disrupt the recycling process. Because the techniques are expensive, they are particularly suitable for high-quality plastics and composites in electronics and the automotive industry. The technical-economic analysis of processes required to achieve this also forms part of TNO’s expertise.