Combustion behaviour of EVA/fluorohectorite nanocomposites

Octadecylammonium (ODA) or aminododecanoic acid (ADA) exchanged fluorohectorite (FH) was dispersed in ethylene–vinyl acetate copolymer (EVA) in an internal mixer. A nanocomposite was obtainedin the case of FH/ODA with exfoliation of the FH crystalline layers which were separately distributed in EVA as shown by X-ray diffraction (XRD). Whereas distribution of particles formedby multiple crystalline layers with overall size of the order of 1 micron resultedin the case of FH/ADA. In the horizontal combustion mode of the mass loss calorimeter, the nanocomposite shows acceleration of EVA deacetylation and delayed volatilisation of the resulting polyene. The overall heat release rate is much lower than in the case of EVA as measuredby the gas combustion temperature. A partial protection of EVA from the flame is also foundin the case of the immiscible composite although in this case the volatilisation of the polymer during combustion occurs at a larger rate than in EVA alone. Cumulation of the silicate on the surface of the burning specimen may create a protective barrier to heat andmass transfer which is however much more effective in the case of ablative reassembling of crystalline layers of the nanocomposite than in that of the particles of the immiscible composite. Dripping of burning particles in vertical combustion is suppressedonly in the case of the nanocomposite which reduces the hazardof fire spread to surrounding flammable materials.