The Utility of Nanocomposites in Fire Retardancy.

Nanocomposites have been shown to significantly reduce the peak heat release rate, as measured by cone calorimetry, for many polymers but they typically have no effect on the oxygen index or the UL-94 classification. In this review, we will cover what is known about the processes by which nanocomposite formation may bring this about. Montmorillonite will be the focus in this paper but attention will also be devoted to other materials, including carbon nanotubes and layered double hydroxides.

Thermal stability and degradation kinetics of polystyrene/organically-modified montmorillonite nanocomposites.

Organically-modified montmorillonite (MMT) clays have been prepared using ammonium salts containing quinoline, pyridine, benzene, and styrenic groups. The nanocomposites were prepared by melt blending and the formation of nanocomposites was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal stability and flammability were evaluated by thermogravimetric analysis (TGA) and cone calorimetry measurements, respectively.

Polymerically modified layered silicates: an effective route to nanocomposites.

Polymer/clay nanocomposites have been under an extensive investigation for about 15 years. Traditional methods to modify the clay are usually limited to small organic cations, preferably containing long alkyl chain(s), which are exchanged with the inorganic cations in the clay gallery. This article provides a comprehensive review on the strategies for clay modification using polymeric surfactants or polycations: from the synthesis of such surfactants, through the preparation of the polymerically modified clays, and to the fabrication of the respective polymer nanocomposites and their properties.

Nanoconfinement revealed in degradation and relaxation studies of two structurally different polystyrene-clay systems.

Degradation and relaxation studies have been performed on two polystyrene (PS)-montmorillonite clay nanocomposites, one of which has an intercalated PS-clay structure and the other an exfoliated PS-clay brush structure. Compared to virgin PS, both nanostructured materials have demonstrated the following similarities: (a) a high yield of alpha-methylstyrene in the degradation products as measured by infrared spectroscopy; (b) larger values of the activation energy of the thermal degradation as determined by isoconversional kinetic analysis of thermogravimetric data; and (c) larger values of the activation energy for the glass transition as found from the frequency dependence of the glass transition temperature measured by multifrequency temperature-modulated differential scanning calorimetry. These effects are taken as structure independent manifestations of nanoconfinement of the PS chains in the PS-clay materials.