Atomization of dilute polyisobutylene/mineral oil solutions

Atomization experiments, motivated by the need to suppress misting of machining oils, were conducted on dilute solutions of high molecular weight polyisobutylene (PIB) in mineral oil. Polymer concentrations and molecular weight were varied to determine their effects on the aerosol's drop size distribution. A marked dependence of aerosol drop size on solution rheology was observed. Under constant atomization conditions, the PIB solutions produce much larger drops than the pure mineral oil, with the degree to which drop size is increased depending strongly on oil viscosity and PIB concentration and molecular weight. The effects of PIB addition on atomization behavior were found to be highly dependent on atomization stress, with the greatest effects on drop size observed at the lower atomization stresses.;The mineral oil/PIB solutions were characterized rheologically by measuring intrinsic viscosities and relaxation time. Since the PIB contribution to solution shear viscosity is small, the observed effects of PIB on atomization is therefore ascribed to the elastic properties of the solutions. These stress dependent elastic properties were examined using a FENE-P model, and the predicted elongation viscosities were found to have a linear correlation to the increases in average aerosol drop size. This correlation correctly accounted for the observed effects of atomization stress, oil viscosity, PIB concentration, and PIB molecular weight.;Similar effects on atomization were observed with dilute aqueous solutions of high molecular weight polyethylene oxide (PEO) and polyacrylamide (PA). The effects of PEO and PA additions on the atomization behavior of oil-in-water emulsions, commonly used as water based machining fluids, were also examined. PA additions to the emulsions yielded similar increases in drop size as were observed with aqueous solutions, while the additions of PEO to the emulsions result in increases in drop size significantly larger observed with comparable aqueous solutions. This additional increase in drop size is possibly due to interactions between the PEO and the surfactants present in the emulsions.