Influence of clays on the flame retardancy and high temperature viscoelastic properties of polymeric intumescent formulations

A natural Brazilian montmorillonite clay was submitted to organophilization treatments to evaluate the effect of these treatments on the flame retardancy potential of polymer composites containing an intumescent ammonium polyphosphate and pentaerythritol formulation. An ethylene-butyl acrylate copolymer was used as the polymer matrix. Natural or organophilic clays were added both to the pure polymer and to the polymer containing the intumescent mixture. The influence of these mineral fillers, and of their organophilization treatments, on flame retardancy was investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 rating standard, heating microscopy, rheological measurements and cone calorimetry. The results show that these inorganic additives have a synergistic effect on composites containing the intumescent formulation.