ARYL PHOSPHINATE ANHYDRIDE CURING FOR FLAME-RETARDANT EPOXY NETWORKS

An aryl phosphinate anhydride ydro-9-oxa-10-phosphaphenanthrene-10-oxi de)-methyl succinic anhydride (DMSA), with a pendent phosphorus group was synthesized and used as a reactive type flame retardant. The struc ture of DMSA was confirmed by FTIR, mass, elemental analysis, H-1 and P-31 NMR spectroscopies. The aryl phosphinate anhydride was successful ly used to cure some commercial epoxides, such as bisphenol A diglycid yl ether (DGEBA) and epoxy-novolac. The epoxy networks obtained were c haracterized by dynamic mechanical analysis (DMA), thermogravimetric a nalysis (TGA), and the limiting oxygen index (LOI) test. Epoxy resins cured with DMSA exhibit higher LOI values and char yields compared wit h those cured by commercial anhydrides, such as phthalic anhydride (PA ) and hexa-hydrophthalic anhydride (HHPA). Furthermore, the LOI value and the char yield of the epoxy-resin composites increase with increas ing phosphorus content. The flame retardancies of the epoxy-resin comp osites were significantly improved by using aryl phosphinate anhydride . (C) 1998 Society of Chemical Industry.