The effects of processing and using different types of clay on the mechanical, thermal and rheological properties of high-impact polystyrene nanocomposites

High-impact polystyrene (HIPS) nanocomposites were prepared by melt compounding two grades of organoclays (Cloisite 10A (C10A) and Cloisite 30B (C30B)) in a Haake internal mixer or a corotating twin screw extruder. The nanocomposites were characterized by transmission electron microscopy, small-angle X-ray diffraction, thermogravimetric analysis, rheometer analysis and tensile and impact testing. The correlation between the morphological and the rheological properties of the nanocomposites was also investigated. As the exfoliation of the samples processed by the twin screw extruder was greater than the exfoliation of the samples processed by the Haake internal mixer, the extruded samples were of better quality than the samples subjected to internal mixing. Furthermore, the HIPS nanocomposite material that was prepared with C10A showed better mechanical properties and thermal stability than the HIPS nanocomposite material that was prepared with C30B. By increasing the clay content, it was observed that the zero shear viscosity increased, whereas the initial slope of the storage modulus (g' = partial derivative g'/partial derivative omega) decreased. A high degree of clay dispersion was obtained for HIPS samples containing a concentration of 2 wt% C10A with an aspect ratio of 177.1, whereas the exfoliated nanocomposite material had an aspect ratio of approximately 300. Polymer Journal (2013) 45, 346-353; doi:10.1038/pj.2012.138; published online 11 July 2012