De‐Brominating Flame‐Retardant Polystyrene by Utilizing Basic Oxides in Chemical Recycling

Abstract Chemical recycling is a method to close the recycling loop for polymers. This is particularly applicable for polystyrene (PS), where the monomer styrene is directly formed by depolymerization and subsequently utilized for the production of new PS. However, some waste sources contain critical additives as legacies, such as brominated flame retardants. There is a profound need to remove these substances from the material, as current thresholds do not allow such additives above certain limits in new products. In this work we present the beneficial use of basic oxides during the thermal depolymerization of a mixture of PS and 1,2,5,6,9,10‐hexabromocyclododecane. It was demonstrated that especially barium oxide and calcium oxide allowed the reduction of bromine up to 96 % in the crude styrene oil.