The use of angular light scattering techniques has proved to be of the highest precision for the size distribution analysis of colloidal size spheres, but is inherently limited to quite narrow, monomodal size distributions of particles of a single chemical component. These limitations can be overcome to a limited degree by a technique that utilizes light scattering and a preparative ultracentrifuge. The latter fractionates the colloidal particles according to density (i.e., chemical com position) and/or size. Applying the zonal ultracentrifugation technique, both types of separation take place in the presence of a density gradient and ultimately fractionated samples are obtained which are then characterized by light scattering to provide size distribution parameters. The size parameters assigned to each fraction can then be used to reconstruct the original size distribution. A further use of the technique will be demonstrated using a %T vs. fraction number curve obtained from a recording spectrophotometer which is on line between the rotor and the fraction collector. By calibration of the rotor using the ultracentrifuge-light scattering technique above, the %T vs. fraction number curve can be converted to a plot of relative frequency vs. diameter. The above techniques will be applied to broad continuous distributions, monomodal distributions and to a mixture of polystyrene, polyvinylchloride, and polyvinylacetate latexes of different sizes.

Library of Congress Subject Headings

Centrifuges; Light--Scattering

Publication Date


Document Type


Department, Program, or Center

School of Chemistry and Materials Science (COS)


Wallace, Thomas


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in December 2013.

Physical copy available from RIT's Wallace Library at QD54.C4 C4


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