Featured structures of fire residue of high-impact polystyrene/organically modified montmorillonite nanocomposites during burning

The structures and constituents of fire residue of high-impact polystyrene/organically modified montmorillonite (HIPS/OMMT) nanocomposite during burning was investigated using scanning electron microscopy, thermogravimetric analysis, X-ray diffraction analysis, and elementary analysis techniques and based on quenched samples obtained during the cone calorimeter test. It was found that during burning the HIPS/OMMT nanocomposite tends to form a two-layer structure of fire residue on the surface of material. This two-layer structure contains a thin and condensed skin layer at the top and a loose and expanded cellular layer under the skin layer. The skin structure contains many small sizes of voids, while the cellular structure includes a large number of large-size voids. Both the skin and cellular layers are composed of mainly montmorillonite platelets, which are aggregated to form a nanoscale network structure, in which certain amounts of carbonaceous char components are trapped during burning but decompose above approximately 550 degrees C in the presence of oxygen. Finally, an idealized model was put forward to explain the featured structures of fire residues for the nanocomposite studied. Copyright (c) 2012 John Wiley & Sons, Ltd.