Abstract: There is provided an improved method for particle size and distribution determinations using a photosedimentometer having a centrifugal disc chamber for containing a spin fluid. The spin fluid must be characterized by a density gradient. The present process provides a novel way of composing the spin fluid. The less dense component water/alcohol is introduced first, and the more dense component (e.g., water) is introduced second. At no time is the power to the motor driving the disc interrupted as in prior art methods. Better and more reproducible results are secured.

Abstract: Particle size of suspension polymer particles is controlled in the suspension polymerization of a mixture of ethylenically unsaturated monomers including an ethylenically unsaturated monocarboxylic acid and pentaerythritol triacrylate by increasing the proportion of pentaerythritol triacrylate in said monomer mixture to increase the size of the suspension polymer particles.