Effect of Dispersion Stirring Speed on the Particle Size Distribution and Rheological Properties of Carbomer Dispersions and Gels

Studies on the influence of the stirring speed during the dispersion stage of Carbopol 5984 on the particle size distributions and rheological characteristics of the gel showed that increasing the stirring speed leads to a decrease in the particle size and in the polydispersity of the dispersion. These two characteristics have antagonist effects on the viscosity: a decrease of particle size leads to a decrease in viscosity while a decrease of polydispersity leads to an increase in viscosity. In this study, for low stirring speed, even if the particle size decreased, the viscosity remained constant because the polydispersity decreased also. For high stirring speed during the dispersion stage, the polydispersity remained constant and the particle size continued to decrease therefore the viscosity decreased. Therefore it is important to monitor the particle size and polydispersity of Carbopol 5984 dispersion during manufacturing to be able to ensure the rheological properties of the gels produced.