Light-scattering of coatings formed from polystyrene pigment particles

Abstract Coatings prepared from polystyrene latex particles of different sizes (0.03–1.01 μm in diameter) were tested for light-scattering efficiency. The variation of the light-scattering coefficient with the particle size is in agreement with theoretical predictions, although the absolute values are considerably lower. The most effective particle size is around 0.4–0.5 μm. The data are also interpreted by considering the voids, rather than the latex particles, as the scattering sites. The optimum void size is in the range of 0.2–0.3 μm equivalent spherical diameter. Coatings prepared from mixtures of 0.5-μm latex particles with 0.2−, 0.1−, and 0.03-μm latex spheres have lower light-scattering efficiency than that predicted on the basis of additivity. This is explained by the changes in the void structure caused by increased packing density.