DETERMINATION OP PARTICLE SIZE DISTRIBUTIONS IN EMULSIONS BY LIGHT SCATTERING

摘要

The light scattering method for determining size distributions in liquid dispersoids was found applicable to the spontaneous dimethylnaphthalene emulsions which contained sub-micronic particulates and were approximately 30# more hetero-disperse than the synthetic heterodispersions of "monodisperse" latices used to verify the method experimentally. A bi-parametric, exponential, positively-skewed distribution function closely approximating the distribution law commonly obeyed by emulsions was assumed. The effect of stabilizer concentration, as well as the effect of aging on the size distribution of emulsions, was systematically invest¬igated. As experimental criteria for determining the distribution parameters, two scattering spectra, the turbidity and the scattering ratio as a function of wave¬length, were obtained. Although the turbidity or transmission measurements are, in general, simpler and more accurate than those of scattering ratio, the turbidi¬ty spectra was found too insensitive to give an independent, unambiguous estimate of sizes in these moderately heterodlsperse systems. Final results for the dis¬tribution analyses were based primarily on scattering ratio spectra. Electronic comparison and fitting of the experimental with the theoretical scattering spectra corresponding to various distribution parameters were accomplished with the IBM 7070 computer. This part of the distribution analysis was rapid, precise, and successful in reducing considerably the time required for a complete size distri¬bution analysis.