Morphology and Rheology of PS/SEBS Blends with Co-continuous Lamellar Nano-structure
Sumanta Raha, Nhol Kao, Ferenc Cser, Sati N. Bhattacharya
Rheology and Materials Processing Centre, RMIT University
Australia

Keywords: PS/SEBS rheology, co-continuous blends, lamellar nano-structure

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Polystyrene (PS) was blended with styrene-b-ethylene/butylene-b-styrene triblock co-polymer (SEBS) to produce co-continuous lamellar nano-structures. The morphology and rheological behaviour of these blends were investigated and the effects of morphology on the rheological behaviour of these blends were studied. PS was blended with SEBS by melt extrusion using a twin-screw extruder. The morphology of these PS/SEBS blends was investigated by using an Environmental Scanning Electron Microscope (ESEM). Morphological studies showed formation of co-continuous lamellar nano-structures in the blends when SEBS concentration was above 20 wt%. From the ESEM studies, at least one dimension of these co-continuous lamellar structures was observed to be in the nanometer scale. When the SEBS concentration was below 20 wt%, a dispersed morphology of SEBS was found within the PS matrix. Rheological studies were carried out on these PS/SEBS blends. In this paper, results from dynamic shear rheological experiments are presented. The correlation between the morphology of PS/SEBS blends and their rheological behaviour are analysed and discussed using two simple models.