Solid state NMR characterization and flammability of styrene–acrylonitrile copolymer montmorillonite nanocomposite

This work investigates the melt-processing of styrene–acrylonitrile copolymer (SAN) with organo-modified montmorillonite (MMT) clays and the influence of the clay on mechanical properties and on fire performance of SAN. The nanodispersion of MMT is evaluated qualitatively by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), and quantitatively by solid state nuclear magnetic resonance (NMR). SAN/MMT nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and with the presence of small tactoids, whatever the loading in MMT is. The polymer–clay interfacial area is estimated at 0.5 and the degree of homogeneity characterizing the distribution of MMT platelets is about 40%. The presence of clay in SAN-25 leads to a ‘filler effect’ increasing the stiffness but decreasing tensile strength of the nanocomposites. It also leads to a significant decrease of peak of heat release rate measured by mass loss calorimetry.