Applications of the rheodielectric technique

An apparatus for dynamical mechanic measurements was modified in order to allow broadband dielectric spectroscopy measurements (10 mHz to 10 MHz) on systems under shear stress. Shear oscillatory deformation was applied to different systems under conditions of controlled deformation amplitude, choosing different shear frequencies and amplitudes, including the range of the non-linear viscoelastic response. The plate-plate geometry was used, with the two metallic sample holders serving both as mechanical tools and as electrodes of a capacitor. The rheo-dielectric technique was used to study the effect of oscillatory shear on two classes of systems: nematic liquid crystals and polymeric melts.