Flame Retardancy of Polycarbonate upon Repeated Recycling

Abstract

In this study, two polycarbonates are put through multiple cycles of a process that involves drying the resin, extruding, and pelletizing it, drying the pellets and injection molding them into test specimens, followed by granulation. While one of the polycarbonates contain potassium diphenylsulfone sulfonate (KSS) as a flame retardant, the other polycarbonate is flame retarded with bromine. The recycling process is repeated up to eight times, and after each cycle, flammability and mechanical tests are conducted. Thermogravimetric analysis and capillary rheometry are also performed. It is found that both flame retardants maintain their effectiveness, but the notched Izod impact strength suffers upon recycling, with the polymer containing KSS displaying marginally better mechanical properties.