Influence of organoclay filler on the properties of polystyrene/low-density polyethylene blend

The present work deals with the study of nanocomposites based on polystyrene (PS)/low-density polyethylene (LDPE) blend and an organophilic clay (Bentone 38 (B38)). Different PS/LDPE/B38 mixtures were prepared via melt intercalation process using a two-roll mixer and a single-screw extruder. Analysis of the nanocomposites by means of X-ray diffraction showed that the characteristic peak of the clay appears only at 3% wt. content, indicating an intercalated structure of PS/LDPE/3% B38 nanocomposite. The mechanical properties of the nanocomposites reflected the effect of the addition of the filler as well as the state of interfacial adhesion between the polymer blend matrix and the filler. The incorporation of the clay into PS/LDPE blend resulted in a relative increase (particularly at 0.5% wt.) of the stress at break and microhardness owing to the interfacial interactions developed between the PS/LDPE matrix and the clay and between the two blend phases. This is in good agreement with PS/LDPE/B38 nanocomposites rheological behavior which revealed an increased maximum torque most pronounced at 0.5% clay weight. Scanning electron microscopy micrographs showed, for this same clay content, the compatibilization effect of the clay between PS and LDPE. This was also confirmed by the atomic force microscopy images and by differential scanning calorimetry analyses.