Reactive flame retardancy of cyanate ester/epoxy resin blends and their carbon fibre reinforced composites

Cyanate ester/epoxy resin (CE/EP) blends consisting of diglycidyl ether of bisphenol A (DGEBA) and novolac type cyanate ester (CE) were prepared and reactively flame retarded using an epoxy functional adduct of DGEBA and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Moisture uptake was measured by the gravimetric method; consequent carbamate formation was detected by infrared spectrometry. Effects of cyanate ester : flame retardant ratio were determined on glass transition temperature (Tg), thermal stability and flammability. The addition of CE compensated the Tg decreasing effect of DOPO. Reactively flame retarded CE/EP carbon fibre reinforced composites had LOI of 48 V/V%, V-0 UL-94 rate and peak of heat release rate of 84 kW/m2.