Thermo-physical performance of organoclay coatings deposited on the surfaces of glass fibre-reinforced epoxy composites using an atmospheric pressure plasma or a resin binder

• Organoclay coatings are deposited on polymer composites using plasma or resin binder.
• Argon plasma helps in bonding the clay to the epoxy surface.
• The organoclay coating acts as a thermal barrier and provides passive fire protection.
• For the coating to be self-extinguishing an additional flame retardant is required.

This work reports the thermal barrier and flame retardant efficiency of an organically modified clay (organoclay, OC), when deposited on the surface of glass fibre-reinforced epoxy (GRE) composites. Two approaches were undertaken: 1) the OC was deposited on the surface of the epoxy composite and then polymerised using an atmospheric argon plasma in the presence and absence of a silicon-containing monomer and 2) the OC was dispersed in a phenolic resin binder and applied as a surface coating. Fourier transform infrared spectrometry confirmed the polymerisation of the silicon-containing monomer by plasma treatment. The adhesion between the coating and the substrate was measured using the tape pull method, which indicated that the OC was tightly embedded in the resin matrix after plasma treatment or with the resin binder. The surface morphology of coated surfaces was studied using scanning electron and digital microscopies. The thermal barrier effect of the OC-containing coatings studied by a cone calorimeter at 35 kW/m2 heat flux was demonstrated by increase in time-to-ignition and time-to-peak heat release rate, and decrease in the peak heat release of the coated samples compared to the control sample. However, for the coatings to be effective enough to be self-extinguishing, the presence of an additional flame retardant element in the coating or on the surface layer of the GRE composite and beneath the clay layered coating is required.