A rheo-optical apparatus for simultaneous detection of rheology, small-angle light scattering, and optical microscopy under transient, oscillatory, and continuous shear flows

A rheo-optical apparatus is constructed by installing a small-angle light scattering instrument and an optical microscope in a rheometer to investigate relationships between rheological properties and structures in complex liquids (or soft condensed matters). The apparatus is designed in such a way that it really enables us to measure simultaneously the rheological properties, light scattering, and transmission optical micrographs under both steady and dynamic shear field. It covers over a wide range of torque: it is applicable to systems having only the small viscosity of water similar to 1 mPa as well as polymer systems in bulk having a high shear modulus G' similar to 10(9) Pa. An assembly of lens and a cooled charge coupled device camera allow us quantitative measurements of 2D light scattering patterns. For dynamic shear field, both light scattering measurements and optical microscopy observations can be synchronized with a given strain phase phi, defined in the text. Preliminary experiments with the apparatus are demonstrated for polymer mixtures with a common solvent and for semidilute polymer solutions. (C) 1999 American Institute of Physics. [S0034-6748(99)03905-2].