Thermally-
activated non-reversible response of polystyrene/polyvinyl methyl ether (PS/PVME)
sandwich sample under small-amplitude oscillatory shear flow
R. Levesque, S. Vaudreuil, F. Mighri, and M.
Bousmina*
Canada Research Chair on Polymer Physics and Nanomaterials. Department of Chemical Engineering, CRASP (École Polyetchnique, Montréal), Laval University, Sainte-Foy G1K 7P4, Canada
Small amplitude oscillatory shear modulus was measured for a sandwich type assembly made of polystyrene (PS) and polyvinyl methyl ether (PVME) as a function of time at constant temperature and as a function of temperature at constant frequency. Diffusion coefficient in the miscible region was obtained from the time sweep experiments. The obtained mutual diffusion coefficient was found to be in agreement with the value determined using attenuated total reflection-infrared spectroscopy measurements. A peculiar non-reversible behavior was observed when the sandwich sample was heated and cooled between 40 and 160oC. Such a behavior was associated with the difference in kinetics between phase segregation and phase homogenization of the PS/PVME blend.