Particle size of poly (vinyl chloride) latices and rheology of poly (vinyl chloride) pastes

Abstract An anlytical centrifuge for the determination of particles in the micron and submicron range is described. The sedimentation of particles is visualized on an oscilloscope, where light‐absorption curves give an apparent size distribution. The true size distribution can be calculated from the oscilloscope curve. The centrifuge has been especially applied for analysis of PVC latex particles. Sedimentation time is about 10 min. On a later model, four samples can be compared directly on the oscilloscope. A comparison between the centrifuge and electron microscope is given. The particle size of PVC latex is strongly dependent on type and concentration of the emulsifier used. Sodium octyl sulphate gives large particles. A short description of some fundamental characteristics of PVC paste rheology is given. Viscosity curves for PVC made from mixtures of latices of four different particle sizes show that the viscosity can be altered by altering the proportions between small and large particles. Examples of high and low viscous PVC pastes are given.