Abstract
A vinyl phosphonic acid based flame retardant coating has been applied on the surface of a glassfibre reinforced epoxy (GRE) composite substrate using a UV polymerisation technique. On exposure to heat the poly (vinyl phosphonic acid) (PVPA) coating thus obtained, intumesces and acts as a thermal insulator, providing active fire protection to the composite structure. Samples with ~300 and 500 μm thick coatings were prepared. The fire performance of the coated GRE composite was studied by cone calorimetry at 35 and 50kW/m2 heat fluxes. While the sample with ~500 μm thick coating did not ignite at both heat fluxes, the one with the ~300 μm thick coating ignited at 50 kW/m2, however the time-to-ignition was delayed from 60 s in the uncoated sample to 195 s and the peak heat release rate reduced from 572 kW/ m2 to 86 kW/ m2. The coatings did not peel off when subjected to a tape pull test and resisted cracking/debonding during an impact drop test of upto 5 J energy. However, the coatings are hydrophilic, showing significant mass loss in a water soak test. The improvement of the hydrophobicity of these coatings is a focus of our future research.