Rayleigh light scattering from concentrated solutions of polystyrene in cyclohexane

Abstract

The Rayleigh light scattered at 90° by concentration fluctuations in solutions of polystyrene with cyclohexane, in the mass concentration range 0.18–0.56 of polymer, is observed to mix with a heterodyne efficiency close to unity with light scattered elastically by dust particles. A technique is described where by using a digital photon correlator the absolute intensity of the Rayleigh light is measured and the elastic modulus of the uncross-linked polymer gel deduced. The results are in satisfactory agreement with values found in the literature. The measurements of the relaxation time of the concentration fluctuations allow the friction constant between the solvent and the polymer matrix to be calculated.