Approach for Particle Sizing in Dense Polydisperse Colloidal Suspension Using Multiple Scattered Light

Direct particle sizing of colloidal suspensions at high solid concentrations is difficult due to confounding effects of multiple scattering and particle interactions. In this work, the frequency domain photon migration (FDPM) technique, based upon multiple light scattering, is extended for particle sizing of colloidal suspensions at high volume fractions by combining an appropriate model to account for particle interactions. FDPM measurements of isotropic scattering coefficients were conducted to assess the effect of particle interactions of polydisperse polystyrene samples at high volume fractions ranging from 1% to 40%. The isotropic scattering coefficients were then compared with the theoretical predictions which include the full polydisperse hard sphere Percus−Yevick (HSPY) model as well as the decoupling approximation and the local monodisperse approximation models to account for excluded volume effects. Results show that the polydisperse HSPY model is suitable for accounting for particle interaction...