The effect of the combined application of solid- and gas-phase flame retardants in epoxy gelcoats on the thermal stability, fire performance and adhesion of coated carbon fibre–reinforced epoxy composites

Abstract We explored the combined effect of two flame retardants (FR) containing phosphorus—ammonium polyphosphate (APP) and resorcinol bis(diphenyl phosphate) (RDP)—on fire performance coated carbon fibre–reinforced composites. prepared epoxy gelcoats with 10% total phosphorus content different ratios APP RDP characterised by DSC, TGA, rheometry, limiting oxygen index, UL-94 test mass loss calorimetry (MLC). The increasing ratio liquid led to a significant reduction in viscosity: over 3%P became sprayable without any diluents. gelcoat 7%P had best (pHRR 141 kW m −2 ), followed 6%P 4%P 171 ). flame-retarded reference epoxy/carbon composites hand lamination, wet compression vacuum infusion. flammability laminates decreased fibre due resin content; therefore, vacuum-infused sample performed best. However, more compact structure sample, heat release was greater than expected from alone. MLC results indicated that it not necessary incorporate composite matrix composites, as FRs coating alone are sufficient protect composite. adhesion between influenced presence FR additives resins, stronger when contained same FR.