Mechanical, thermal and rheological characterization of polystyrene/organoclay nanocomposites containing aliphatic elastomer modifiers

Abstract

In this study, organoclay containing polystyrene (PS) based nanocomposites were prepared by extrusion in the presence of aliphatic elastomer modifiers. Three different types of aliphatic elastomeric materials and three different types of organoclays were used. Their effects on the morphology, and mechanical, thermal, and rheological properties of PS were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD), tensile and impact tests, differential scanning calorimetry (DSC), and melt flow index measurements, respectively. Lotader AX8900, Lotader AX8840 and Lotader 2210 were chosen as the aliphatic elastomeric compatibilizers; and Cloisite 15 A, Cloisite 25 A and Cloisite 30B were chosen as the organoclays. The organoclay content was kept constant at 2 wt% and elastomer content was kept constant at 5 wt% throughout the study. Significant improvement is observed on the basal spacing for 30B containing samples according to XRD analysis. SEM studies indicate that the clay particles mostly reside between the PS matrix and the spherical elastomeric domains. Additions of elastomer and organoclay decrease the MFI value of PS. Mechanical test results show that, improvement is observed in elongation at break of unfilled PS with the addition of elastomers. Organoclay addition increases the tensile modulus of PS. According to thermal characterizations, the glass transition temperature (Tg) of PS decreases with elastomer addition, whereas organoclay addition shifts Tg values to higher temperatures.