FLAME-RETARDANT PROPERTIES OF PHENOL-FORMALDEHYDE-TYPE RESINS AND TRIPHENYL PHOSPHATE IN STYRENE-ACRYLONITRILE COPOLYMERS

The thermal and flame-retardant properties of phenol-formaldehyde-type resins (crosslinked and noncrosslinked) in mixtures with triphenyl ph osphate and styrene-acrylonitrile resins were evaluated. The mixtures show a synergistic effect between triphenyl phosphate and novolacs. Th ose containing phenol-formaldehyde novolac resins are found to be most flame retardant. There does not seem to be a relationship between the oxygen index( OI) and UL 94 tests. Scanning electron microscopy analy sis show a surface structure with cavities and stratification, very si milar to that of intumescent additives. Evidence was found indicating that this flame-retardant system works in both the gas and condensed p hase. (C) 1998 John Wiley & Sons, Inc.