The use of clay in an EVA-based intumescent formulation. Comparison with the intumescent formulation using polyamide-6 clay nanocomposite as carbonisation agent

This work deals with the use of clay as a filler in an intumescent EVA-base d formulation using a charring polymer (polyamide-6) as a carbonization age nt. Using PA-6 clay nanocomposite instead of pure PA-6 had been shown to im prove the fire properties of the intumescent blend. In this study, using cl ay as a "classical" filler enabled the same level of FR performance to be o btained in the first step of the combustion as when directly using exfoliat ed clay in PA-6. But in the second half of the combustion, the clay destabi lizes the system and increases the flammability. Moreover, a kinetic modeling of the degradation of the EVA-based formulatio ns shows that adding clay to the blend enables the same mode of degradation and the same invariant parameters as for the polyamide-6 clay nanocomposit e containing intumescent blend. It is assumed that these kinetic data can b e correlated with the improvement of the fire performance in the first step of combustion as observed under the cone calorimeter. The increase in the flammability by the K-10 in the second half of the combustion shows the adv antages of using nanoclay rather than micronclay in an intumescent system.