Polymeric Composites for Secondary Aircraft Structures: Design and Development of Hybrid Si/P–Epoxy Nanocomposites

Epoxy resins are largely used owing to their good thermal and mechanical properties. For this reason, epoxy composites are applied in several industrial applications. The addition of flame retardants in the polymer matrix is necessary to pass specific fire safety requirements. Recently, we proposed a synthetic strategy to produce hybrid Si/P–epoxy flame retardant nanocomposites via a facile synthesis methodology, where the inorganic phase is composed of P-modified silica lamellar nanocrystals. The diffusion of phosphoric acid into silica nanodomains limited its reaction with oxirane rings and allowed for the formation of stable Si–O–P structures at safe and mild conditions. The morphology and chemical features of Si/P–epoxy nanocomposites led to the production of a large amount of continuous char and a notable reduction (up to 27.7%) in the peak of heat release rate, with only a slight detrimental impact on the mechanical performances of the final products.