THE BREAK-UP OF FLUIDS IN AN EXTENSIONAL FLOW FIELD

This research related aerosol mass median diameters (MMDs) to those molecular characteristics which cause non-Newtonian flow in polymer solutions, in order to establish whether break-up behaviour could be predicted from a knowledge of such parameters. A series of known viscosity, low molecular weight, Newtonian fluids, and higher molecular weight, non-Newtonian fluids were tested. Shear and elongational viscosities were measured over a range of shear and strain rates. The effects of the size of the polymer coil on particle size was demonstrated by changing the pH of solutions of polyacrylic acid. For polyethylene glycols (PEGs), and lower molecular weight polyvinyl alcohol (PVA1) solutions, mass median diameter (MMD) as a function of viscosity was found to be independent of molecular weight, and, above some critical viscosity, could be correlated in a similar manner to the Newtonian solutions. For the higher molecular weight PVA1s, the polyvinyl pyrrolidones, and the polyethylene oxides (PEOs), the MMD (as a function of viscosity) was found to depend upon, and could be correlated directly with, molecular weight and concentration. For PEO, as molecular weight rose the particle size distributions became multimodal. This could be explained by phase change in the elongating fluid.