Dynamic viscosity measurements by photon correlation spectroscopy

Abstract

It is shown that absolute values for the dyn:mlic viscosity of liquids can be obtained using photon correlation spectroscopy. The technique is based on the measurement of the particle difl'usion coefficient of spheres dispersed in a liquid.In the experiments both PMIVlA and silica particles were used as a seed. This includes the first application of newly industrially produced silica samples for the goal of viscosity nleastmrements. Experiment results are presented Ibr various liquids at ambient conditions, including some alcohols, alkanes, and the refrigerant RI23. Most of the data agree quite well witll reference values. Requirements for suitable seed particles and possible reasons Ibr deviations from refizrence data are discussed. Measurements in liquid mixtures indicate the general possibility for the simultaneous determination of dynamic viscosity and molecular difl'usion coefficient in a single experiment.

Dynamic Viscosity of Tetracyanoborate- and Tricyanomethanide-Based Ionic Liquids by Dynamic Light Scattering

“…The employed charge of native silica particles (Monosphere 250, provided by Merck KGaA, Germany) with a nominal diameter of 250 nm and a density of 2.65 g•cm −3 at 293.15 K had already contributed successfully to the determination of the dynamic viscosity of acetone, ethanol, and 1-undecanol in 1995. 13 To check the effect of particle size, also smaller native silica particles (Monosphere 100, provided by Merck KGaA) with a nominal diameter of 100 nm were used. The melamine resin particles (MF-F-S1898, nominal diameter 460 nm, standard deviation 30 nm, density 1.51 g• cm −3 at 293.15 K) and the polystyrene particles (PS-F-0.25, nominal diameter 248 nm, standard deviation 8 nm, density 1.05 g•cm −3 at 293.15 K) were purchased from microParticles GmbH, Germany.…”

“…Because of their excellent chemical stability and high monodispersity, commercial native silica, melamine resin, and polystyrene particles were tested regarding their ability of forming stable suspensions with the studied ILs. The employed charge of native silica particles (Monosphere 250, provided by Merck KGaA, Germany) with a nominal diameter of 250 nm and a density of 2.65 g·cm –3 at 293.15 K had already contributed successfully to the determination of the dynamic viscosity of acetone, ethanol, and 1-undecanol in 1995 . To check the effect of particle size, also smaller native silica particles (Monosphere 100, provided by Merck KGaA) with a nominal diameter of 100 nm were used.…”

“…DLS from suspended particles represents a further possibility to measure the viscosity of semitransparent liquids. It has already been successfully applied for simple fluids − and requires only small incident laser powers because of the comparatively strong particle scattering intensities. Small amounts of monodisperse particles are suspended in the studied liquid, and the translational particle diffusion coefficient is measured by DLS.…”

Synthesis of polyacrylamides hydrophobically modified with butyl acrylate using a nanoclay with interlayer spaces for butyl acrylate aggregation: studies on the microstructure and aqueous solution viscosity

“…Hydrodynamic radius of the copolymer chains coil (R h ) in dilute solutions can be studied by DLS. 13,28 Then, one would also be able to analyze the hydrophobic aggregations of the HMPAMs. Number and intensity size distribution curves are illustrated in Fig.…”

Dynamics of Microsphere Suspensions Probed by High-Frequency Dynamic Ultrasound Scattering

“…Among them, DLS based on a correlation spectroscopy technique allows one to investigate complex dynamics of polymer solutions [5][6][7][8] and gels [9][10][11] at a molecular level beyond the diffraction limit. More recently, DLS was employed to detect oligomers 12 or low molecular weight species 13,14 which exhibited fairly rapid relaxation processes. On the contrary, since visible light is not able to pass though opaque media, the samples should be optically transparent by dilution or sufficiently thin to allow transmission of the light source.…”