Eva M. Sevick-Muraca, Purdue University The objective is to develop the frequency domain photon migration (FDPM) technique for assessment of particle size and particle interaction parameters in concentrated suspensions of 10% to 50% by volume. This inverse problem analysis is based upon the light diffusion in turbid, multiple scattering samples. The technique consists in launching intensity-modulated light and monitoring the phase-delay and amplitude demodulation as it propagates through the medium. The measurement can provide either particle size distribution or particle interactions. On-line measurement capabilities will be developed. Particle interactions for polymer induced depletion enhancement, electrostatic repulsion, and steric stabilization of colloidal particles will be measured. If successful, the research will provide a technique for on-line measurement of particle size distribution and particle interactions in dense suspensions of interest in paints, inks, polymer composites and other colloid mixture applications.
