FLAME RETARDANT EPOXY RESINS.pdfVIP

1FLAME RETARDANT EPOXY RESINS C. M. Thompson*, J. G. Smith Jr., J. W. Connell, P. M. Hergenrother National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-2199 and R. E. Lyon Federal Aviation Administration, Atlantic City International Airport, NJ, 08405 ABSTRACT As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed. KEY WORDS: Fire Resistance, Structural Epoxy Resins, Phosphorus Containing Epoxies, Phosphorus Containing Diamines 1. INTRODUCTION The use of composite structures on both commercial and general aviation aircraft has been increasing primarily because of the advantages composites offer over metal (e.g. lower weight, better fatigue performance, no corrosion, better design flexibility, etc.). The new Airbus A380 is predicted to have more than 20% of the structural weight in composites. More than 50% of the structural weight of the new Boeing 7E7 is proposed to be composites, including for the first * National Institute of Aerospace Staff Scientist, 144 Research Drive, Hampton, VA 23666 2time, a composite fuselage. No fire resistance requirements currently exist for exterior