Comprehensive Approach to Flame-Retardancy Evaluation of Layered Silicate Nanocomposites

Abstract The comprehensive assessment of fire-retardant behavior of layered silicate nanocomposites cannot be evaluated by a single test but should include different tests representing different fire scenarios, ranging from ignition to well-developed fires. Each testing setup may show a different behavior of nanocomposites, depending on the different effectiveness of the action of nanoparticles in the different scenario. As an example, flammability tests typically evidence for lower dripping and slower combustion, which are usually detrimental for the ranking of materials accordingly to standards such as UL 94. Conversely, forced combustion tests (e.g. cone calorimeter) show the reduction of burning rate during forced combustion, which was often claimed to relate to a major improvement in material performance in fires, which is in fact very much dependent on fire scenario considered. The development of fire-retardant materials to deliver effective flame retardancy in real fire scenarios should take into account the relevancy of the flame test to the reality of the fire event. However, to allow a broad application range, the development of new flame-retarded nanostructured materials has to be driven by the comprehensive testing of fire properties in different conditions, including ignition, flammability, forced combustion, flame spread, as well as take into account the production of smoke and toxic volatiles during combustion. This chapter critically reviews and comments the behavior of layered silicate polymer nanocomposites in different fire scenarios, with correlations to the mechanisms of action of nanoparticles as flame retardants.