Iron compounds in non-halogen flame-retardant polyamide systems

An effective flame retardant system for polyamide 4,6 was found based on inorganic iron compounds with polyphenylene oxide and zinc borate. Iron compounds have been known as flame retardant synergists in halogen systems but their utility in non-halogen systems has been largely unrecognized. The iron compounds appear to improve char morphology. Polyphenylene oxide provides the char-forming component. Evidence was developed for a positive interaction between the polyphenylene oxide, the iron compound and zinc borate. Favorable results from more recent studies of iron compounds in non-halogen systems are also briefly reviewed. (C) 2003 Elsevier Ltd. All rights reserved.