Chemical recycling technologies
This chapter addresses chemical recycling processes for end-of-life foams and plastics containing brominated flame retardants (BFR). Polymers of concern are polyurethane (PUR) foams from furniture, mattresses, upholstery and building applications, expanded and extruded polystyrene (EPS and XPS) employed as insulation material of buildings as well as polymers like acrylonitrile-butadiene-styrene (ABS) or high impact polystyrene (HIPS) used in electric and electronic equipment. In contrast to above discussed mechanical treatment processes, this chapter reviews chemical recycling processes including depolymerisation processes for polyurethane foams, which produces oligomers and monomers from polymeric PUR foams. These can be applied to synthesis of recycled PU. Other approaches like the CreaSolv® process apply chemicals to dissolve a polymer without affecting the chain length of the macromolecule. As the polymer does not react with the applied solvents, these dissolution based processes may be handled as mechanical processes. However, in this report we treat them as chemical processes due the application of chemicals and the fact that these processes require equipment significantly different from mechanical processes. In addition, dehalogenation processes and extractive technologies are discussed, which eliminate halogens from BFR contained in the matrix or separates brominated flame retardants from the polymer matrix. Thus, the aim of the chosen chemical recycling processes differs significantly.