Phosphorus flame retardants with different chemical environment. Thermal stability and flame-retardant efficiency

Engineering plastics (PA, PBT) have their own high processing temperatures (250-350°C and even higher). To realize fire-resistant polymers it is necessary to compound polymers and flame retardants at these temperatures without a serious change in the characteristics of the polymer. Furthermore, a synergistic interaction of condensed phase and gas phase effects often guarantees in particular for fiber reinforced engineering plastics a maximum of the flame retardant efficiency . The chemical environment of phosphorous compounds (P-O, P-N, P-C) is responsible for the specific flame retardant behavior (1). Due their less plasticizing effect and the marginal tendency of migration bridged rod-like, star-shape, and particularly polymeric compounds are preferred. Here we describe the synthesis and structure of different phosphorus compounds including selected polymers, their thermal stability, and flame retardant efficiency in relation to their chemical environment.