Validation of the poke-flow technique combined with simulations of fluid flow for determining viscosities in samples with small volumes and high viscosities

摘要

Viscosity in particles consisting of secondary organic material (SOM) hasrecently become an area of research focus, since information on viscosity isneeded to predict the environmental impacts of SOM particles. RecentlyRenbaum-Wolff et al. (2013a) developed a poke-flow technique that was combinedwith simulations of fluid flow to constrain the viscosities of SOM samples of1–5 mg mass, roughly the maximum that may be collected from environmentalchambers or flow tubes on a reasonable timescale. The current manuscriptexpands on the initial validation experiments carried out by Renbaum-Wolff etal. First, the poke-flow technique combined with simulations of fluid flowwas used to determine the viscosity of sucrose–water particles over arelatively wide range of relative humidities (RHs). The lower and upperlimits of viscosity at 59% RH were 1.0 × 10 and1.6 × 10 Pa s, whilst at 37% RH the corresponding valueswere 7.2 × 10 and 4.7 × 10 Pa s, respectively.The results are in good agreement with recent measurements byQuintas et al. (2006) and Power et al. (2013). Second, the approach was usedto determine the viscosity of two polybutene standards. The simulated lowerand upper limits of viscosity for standard #1 was 2.0 × 10 and1.2 × 10 Pa s, whilst for standard #2 the correspondingvalues were 3.1 × 10 and 2.4 × 10 Pa s. Thesevalues are in good agreement with values reported by the manufacturer. Theresults for both the sucrose–water particles and the polybutene standardsshow that the poke-flow technique combined with simulations of fluid flow iscapable of providing both lower and upper limits of viscosity that areconsistent with literature or measured values when the viscosity of theparticles are in the range of≈ 5 × 10 to ≈ 3 × 10 Pa s.