Preparation and characterization of poly (styrene-acrylonitrile) (SAN)/clay nanocomposites by melt intercalation

Poly (styrene-acrylonitrile) (SAN)/clay nanocomposites have been prepared by melt intercalation method from pristine montmorillonite (MMT), using hexadecyl trimethyl ammonium bromide (C16) and hexadecyl triphenyl phosphonium bromide (P16) as the reactive compatibilizers between polymer and clay. The influence of the reactive compatibilizers proportion relative to the clay on the structure and properties of the SAN/clay nanocomposites is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), high-resolution electron microscopy (HREM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The effects of the two different clays (MMT and organic modified MMT) on the nanocomposites formation, morphology and property are also studied. The results indicate that the SAN cannot intercalate into the interlayers of the MMT and results in microcomposites. In the presence of the reactive compatibilizers, the dispersion of clay in SAN is rather facile and the SAN/clay nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and the presence of small tactoids. The appropriate proportion with 3 wt% reactive compatibilizers to 5 wt% MMT induces well-dispersed morphology and properties in the SAN matrix. The TGA analyses show that the thermal stability properties of the SAN/clay nanocomposites have been improved compared with those of the pristine SAN. The DMA results show that the storage modulus and glass transition temperature (Tg) of the SAN/clay nanocomposites have remarkably enhancements compared with the pristine SAN. At last the intercalation mechanism of the technology is discussed.