A MELT RHEOMETER WITH INTEGRATED SMALL-ANGLE LIGHT-SCATTERING

A stress-controlled commercial rheometer has been equipped with small- angle light scattering (SALS) instrument working in a range of wave-ve ctors between 0.5 and 4.2 mum-1. By a specially designed optical syste m the scattered light is focused directly on the square chip of a CCD- detector with high dynamical range allowing quantitative two-dimension al (2D) intensity measurements of polarized and depolarized scattering . The rheo SALS system is suited for simultaneous fast measurements of 2D SALS and rheological material functions of polymer melts and liqui d crystals. As a first application results on the influence of shear r ate on the late stage of spinodal decomposition of a polybutadiene/pol yisoprene blend are reported. A second application concerns a creep ex periment in the liquid crystalline phase of a lyotropic non-ionic surf actant with simultaneous measurement of the time-dependent compliance and associated changes of the 2D intensity patterns of the polarized a nd depolarized scattering.