POLYBUTADIENE LATEX PARTICLE-SIZE DISTRIBUTION ANALYSIS UTILIZING A DISK CENTRIFUGE

Polybutadiene latexes made in emulsifier-free emulsion polymerization with diameters ranging from 50 to 300 nm of both unimodal and bimodal particles size distributions were analyzed by the line-start (LIST) me thod in a Brookhaven Disk Centrifuge Photosedimentometer (DCP). A spec ial spin fluid was designed to be able to sediment polybutadiene since the density of the polymer is 0.89 gcm(-3) and is thus less dense tha n its suspending medium. Density and viscosity gradients were created simply by adding five different mixtures of ethanol, water, and emulsi fier in density sequence to the spinning disk. Coagulation problems ca used by diluting polybutadiene latices with ethanol were overcome by u sing nonionic Triton X-100 surfactant. Good agreement in the average p article size and distribution as well as polydispersity between transm ission electron microscope and disk centrifuge data was accomplished. The analysis time for polybutadiene latex particle sizing thus was red uced from several days to approximately 1 h.