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Atomization of dilute polyisobutylene/mineral oil solutions
Author(s) -
Smolinski Joseph M.,
Gulari Esin,
Manke Charles W.
Publication year - 1996
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690420502
Subject(s) - viscosity , chemistry , drop (telecommunication) , viscoelasticity , mass fraction , mineral oil , aerosol , analytical chemistry (journal) , ultimate tensile strength , thermodynamics , composite material , materials science , chromatography , organic chemistry , physics , telecommunications , computer science
Atomization experiments, motivated by the need to suppress misting of machining oils, were conducted on dilute solutions of polyisobutylene (PIB) in mineral oil using a coaxial air blast atomizer and an optical (Fraunhofer diffraction) particle sizer. Polymer concentrations (0.1 to 1.0 kg/m 3 ) and molecular weight (1.0 to 2.2 million) were varied to determine their effects on aerosol drop‐size distributions. The pure oil and PIB ‐ oil solutions were atomized at air/liquid mass ratios near 10 and atomizing air velocities of 150–270 m/s, producing droplet‐size distributions with mass mean diameters (MMD) in the range of 7–15 μm for the pure oil. Under identical atomization conditions, the MMDs of PIB solutions were 20–200% higher than pure oil. These observed increases in MMD correspond to significant reductions in the fraction of droplets falling below 5 μm in diameter that constitute the misting problem in industrial machining applications. Observed effects of PIB on atomization are ascribed to the viscoelastic properties of PIB ‐ oil solutions as characterized by the elongational viscosity η E . This relationship is examined by correlating the change in MMD caused by PIB addition with the stress‐dependent elongational viscosity of PIB‐oil solutions as predicted by the FENE‐P dumbbell kinetic theory. The increase in MMD due to PIB varies linearly with the predicted η E at constant atomization tensile stress.