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    Improvement of organoclay dispersion into polystyrene-based nanocomposites by incorporation of SBS and maleic anhydride-grafted SBS
    (Sage Publications Ltd, 2020) Dike, Ali Sinan; Yilmazer, Ulku
    In this study, organoclay-containing polystyrene (PS)-based nanocomposites were fabricated by extrusion in the presence of thermoplastic elastomer modifiers. Styrene-butadiene-styrene (SBS) rubber was used as the elastomeric compatibilizer and maleic anhydride (MA) was grafted onto SBS rubber at different ratios. Grafting was made via melt blending. Cloisite (R) 30B was used as the organoclay and it was added to PS and PS/SBS blends using a corotating twin-screw extruder, followed by injection molding. Clay loading was kept constant as 2 wt%, and the elastomer content was varied between 0 and 40 wt% throughout the study. MA grafted SBS enhanced the intercalation/exfoliation of clay layers resulting in higher tensile strength, modulus, elongation at break, and impact strength with respect to neat PS. Composites containing 15 wt% MA grafted SBS displayed the optimum average domain size resulting in the high impact strength without deteriorating the tensile strength and modulus values. Elastomer addition increased the glass transition temperature of the samples due to branching or cross-linking during extrusion. PS and PS/SBS exhibited similar melt flow index values with their organoclay-containing composites. MA acted as a plasticizer and decreased viscosity. Scanning electron microscopy study indicated that dispersion of clay layers was observed at the PS-SBS interphase and also in the elastomer phase. Intercalated and exfoliated structures of organoclay layers were confirmed by X-ray diffraction and transmission electron microscopy analyses.
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    Öğe
    Mechanical, thermal and rheological characterization of polystyrene/organoclay nanocomposites containing aliphatic elastomer modifiers
    (Iop Publishing Ltd, 2020) Dike, Ali Sinan; Yilmazer, Ulku
    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 (T-g) of PS decreases with elastomer addition, whereas organoclay addition shifts T-g values to higher temperatures.