RHEOLOGICAL PROPERTIES OF SEMIDILUTE SOLUTIONS USING LIGHT-SCATTERING

We propose an approach to use a light-scattering technique as a probe for measuring the rheological properties of semidilute solutions of polymer molecules. The heterodyne spectrum of scattered light is related to the displacement vector of the excited sample. Taking the cross-correlation function of the scattering intensity and the exciting electrical signal, it is possible to show that the phase difference between the disturbance and the response of the system can be obtained; furthermore, the ratio between the amplitudes of the disturbance and the response can also be obtained up to a normalization constant. Using this information, it is possible to obtain, with some initial reference, the linear rheological behavior of the polymer sample as a function of the exciting frequencies.