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

SUMMARY 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°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.