Measurement Of Viscosity And Particle Size Distribution Of Concentrated Colloidal Suspensions

Viscosity and particle size are key parameters for characterizing the properties of colloidal suspensions. To measure the effective viscosity and particle size distribution of colloidal suspensions is significant. The effective viscosity of the colloidal suspension exhibit different variation from the conventional solution. There are different crucial parameters influencing the viscosity of colloidal suspensions. Such as temperature, volume concentration, particle size, dispersion method, stabilizers, etc. Consequently, it’s difficult to measure the behavior of colloidal suspensions precisely. Many methods and instruments have been developed to measure the effective viscosity and particle size distribution. Light scattering measurement is widely developed and applied due to its unique advantages, and dynamic light scattering has become the development trend of particle measurement technology. However, the traditional dynamic light scattering method applies only to dilute solution, it has a grate limitation to measure the particle size distribution of polydisperse particles in concentrated suspension.A novel method of low-coherence fiber optic dynamic light scattering is proposed to measure the dynamic characteristics of colloidal suspensions. Based on the single scattering theory, the effective viscosity is obtained by analyzing the single scattering spectra that are measured by using low coherence fiber optic dynamic light scattering method. A number of experimental data on the viscous at Brownian short-times of colloidal suspensions is compared with theory. As a result, the measured effective viscosity is in good agreement with the theoretical values by considering the Carnahan-Starling approximation, and effective viscosity of colloidal suspensions with the accuracy approximately5%can be obtained. This novel method gives accurate viscosity over a range of temperature from281K to308K and a range of volume fraction from0.01to0.1. It’s confirmed that the low fiber optic dynamic light scattering method can be used to measure the effective short-time viscosity of colloidal suspensions at different volume fractions and temperatures. The particle size distribution for polydispersed polystyrene latex suspensions were measured by low-coherence fiber optic dynamic light scattering. An improved iterative CONTIN algorithm is proposed for particle size distributions from the experimental data. It’s show that in concentrated polydisperse suspensions, the particle sizes with the accuracy approximately4%can be obtained. They are in good agreement with the polystyrene standard size values. The proportion of weighted intensity of scattering light presented by particle size distribution curves are in good agreement with the theoretical values which calculated by Mie theory. It’s confirmed that the low-coherence fiber optic dynamic light scattering technique can measure the particle size and size distribution well for polydispersed suspensions.