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Poly(vinyl chloride)/montmorillonite (PVC/MMT) nanocomposites were synthesized via in situ intercalative polymerization and their thermal properties were examined by means of thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The nanocomposites exhibited a little higher glass transition temperature in comparison with pure PVC. The presence of organophilic montmorillonite enhanced the rapidest decomposition temperature and reduced the maximum decomposition rate and the onset decomposition temperature. At high temperature, a compact char formed in the surface of the nanocomposites, obstructing the thermal degradation of the polymer matrix. The compact char surface was characterized by Fourier-transformed infrared spectrophotometer (FT-IR). [Copyright &y& Elsevier]

Abstract: Polyethylene/clay composites were prepared by melt compounding polyethylene and montmorillonite clay organically modified with different intercalating agents. Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) revealed that PE/clay nanocomposites formed when using a reactive intercalating agent, while only conventional microcomposites were obtained from the common alkylammonium intercalated clay. Mechanical testing indicated that the reinforcement in the nanocomposites was more effective than that in their conventional counterparts. The thermal stability and flammability of the PE/clay nanocomposites were measured by thermogravimetric analysis (TGA) and cone calorimetry. By adding only 2phr organoclay, the peak heat release rate of the nanocomposite was reduced by 54%. Further studies indicated that the improvement of flammability is due to the formation of a clay-enriched protective char during combustion. [Copyright &y& Elsevier]

Smectite clays, such as montmorillonite, are of great industrial value because of their high aspect ratio, plate morphology, intercalative capacity, natural abundance and low cost. In the present work, polypropylene/montmorillonite (PP/MMT) composites have been prepared and their thermal stability and flammability have been investigated. Although the composites are not nano-dispersed, they exhibit higher thermal stability and considerably reduced peak heat release rate (PHRR). This is probably due to physico-chemical adsorption of the volatile degradation products on the silicates. On the other hand, the addition of MMT can catalyse the initial decomposition of PP matrix and accelerate its ignition in combustion. It has been observed that a ceramic-like char formed on the surface of the composites during the combustion test. The characterization of the char surface prior to ignition indicates that it is an inorganic-rich surface, leading to improvement of the thermal stability and reduction of flammability of the composites because of its better barrier properties. [Copyright &y& Elsevier]