CHARACTERIZATION OF PARTICLE-SIZE AND SIZE DISTRIBUTION OF MULTI-SIZED POLYMER LATTICES BY CENTRIFUGATION PLUS QUASI-ELASTIC LIGHT-SCATTERING

A method for characterizing the particle size and size distribution of multi-sized polymer lattices was developed by combining quasielastic light scattering (QELS) with a centrifuge. Lattices were first fractio nated by centrifugation and the different populations of particles wer e separated in successive steps. The size of these particles was measu red by QELS, and the mass fraction of the particles was determined gra vimetrically. The particle size and size distribution of several blend s of monodisperse lattices and two industrial multi-sized lattices hav e been measured by this method. The results show that the particle siz es obtained using this method are in good agreement with the expected particle diameters, and that the relative amounts of the different gro ups of particles in the blends can be accurately determined, The effic iency of centrifuge-QELS was also confirmed by comparison with other t echniques such as transmission electron microscopy (TEM), QELS, field- flow fractionation (FFF) and capillary hydrodynamic fractionation (CHD F). However, this method is nor suited for the analysis of continuous, broad distributions or mixtures with. a high number of different popu lations. It is better suited for distributions with a small number of families of particles, and then can be used for preparative propose on a laboratory scale.