Morphology of PS/PMMA blends and their solution rheology

Polystyrene (PS)/Polymethylmethacrylate (PMMA) blends were prepared by using solution casting method. These polymers show a tendency of mixing each other in compositions where PS is 60 wt. % or above. PS and PMMA mixed partially and formed PS-rich-phase and PMMA-rich-phase in the blend. Morphology of PSIPMMA blend prepared by solution method is discussed with the help of fractured micrographs obtained by Scanning Electron Microscope. Flow curves of solutions of PS and PMMA and their blends in toluene were studied at room temperature. The effects of blend concentration and composition on shear stress and shear viscosity were studied. The viscosity data was obtained for various weight percent of PMMA and PS separately. 15 and 20 wt% solutions of PS/PMMA blends were also studied. Power law model was fitted for shear dependency of viscosity of solutions. Shear stress increases with the addition of PS in PS/PMMA blend solution. Increase in concentration of PMMA decreased the viscosity of the PS/PMMA solution. All these systems behave as pseudoplastic systems