Particle sizing in highly turbid dispersions by Photon Density Wave spectroscopy: Bidisperse systems

•Experimental evaluation of dependent light scattering model for bidisperse systems.•Successful particle sizing in highly concentrated bidisperse polymer dispersions.•Relative amount of small and large particles is successfully obtained.

Photon Density Wave (PDW) spectroscopy is applied for characterizing the scattering properties, i.e. the reduced scattering coefficient μs′, of highly concentrated mono- and bidisperse polymer latices. The theory for dependent scattering is reviewed and analytical expressions for the structure factors for hard sphere interaction in mono- (HSPYA) and bidisperse (BHSPYA) systems are given. From the scattering properties particle sizes of mono- and bidisperse polystyrene latices are determined as well as the relative amount of small and large particles for the bidisperse case.