Thermal Properties and Flame Retardance of Phosphorus-Silicon-Containing Epoxy Resins

M. SPONTÓN; J. C. RONDA; M. GALIÀ; V. CÁDIZ

Bolton

Congreso; European Meeting on Fire Retardant Polymers; 2007

Epoxy resins are used worldwide on a large scale for adhesive, lamination, coating applications,so forth. They have excellent moisture, solvent and chemical resistances, toughness, lowshrinkage on cure, high adhesion to many substrates and superior electrical and mechanicalresistance properties [1]. To extend the applications of epoxy resins as electronic materials andin the aerospace industry, it is crucial to improve their thermal and flame resistance.Halogenated compounds have been widely used as flame retardant in the past. The majorproblem encountered with these systems is the fire hazards derived from the formation of highlytoxic and corrosive products during combustion. With safety and environmental concerns inmind, epoxy resins that are flame resistant and halogen-free have been the focus of attention byresearchers in recent years [2], [3].Among non-halogenated flame retardants, phosphorus-containing compounds are attractiveowing to their low generation of smoke and toxic gases and the high flame retardant efficiency.Moreover, enhancement of flame retardancy of epoxy resins has been achieved by incorporationof phosphorus and silicon into epoxy resins with bringing a P-Si synergistic effect of flameretardation[4]. While under flame exposure, phosphorus provided a tendency for char formation,silicon provided an enhancement of the thermal stability of the char and introducing bothelements successfully combines these two factors in a strong flame retardation mechanism.In our search for new flame retardant epoxy monomers and curing agents, we consideredphosphine oxides. We synthesized the diglycidyl ether of (2,5-dihydroxyphenyl)diphenylphosphine oxide and investigated its thermal behaviour and reactivity. We also investigatedsilicon-containing compounds as flame retardants: diglycidyloxy methyl phenyl silane and 1,4-bis (glycidyloxydimethylsilyl) benzene.In the present work, phosphorus and silicon were introduced into the epoxy resins by curingphosphorus and silicon epoxy monomers with diaminodiphenylmethane (DDM) or a phosphorusor silicon-containing diamines. In this way, the phosphorus and silicon contents of the resinswere altered. The degradation behaviours and flame retardant properties were investigated toexamine the phosphorus-silicon synergistic effect.