Search results for "VISCOSITY"

Rheological Characterization of Low-calorie Milk-based Salad Dressings

1992

Oil-in-water emulsions of different quantitative composition, containing milk powder and locust bean gum. as stabilizing agents, showed similar rheological behavior: time-dependent thixotropic character and yield stress. Thixograms obtained for each sample could be modelled through the Hahn equation for the different shear rates. The analysis of the Hahn parameter variation for each sample as a function of shear rate led to a function σ= f(γ, t). Predicted shear stress values had relative errors lower than 10% in 99.9% of the samples studied. Analysis of composition influence on the rheological parameters showed an interactive role of gum, milk and acetic acid concentrations on emulsion con…

Do we understand the solid-like elastic properties of confined liquids?

2021

Recently, in polymeric liquids, unexpected solid-like shear elasticity has been discovered, which gave rise to a controversial discussion about its origin (1⇓–3). The observed solid-like shear modulus G depends strongly on the distance L between the plates of the rheometer according to a power law G ∝ L − p with a nonuniversal exponent ranging between p = 2 and p = 3 . Zaccone and Trachenko (4) have published an article in which they claim to explain these findings by a nonaffine contribution to the liquid shear modulus. The latter is represented as Δ G ∝ − ∑ λ = L , T 1 V … [↵][1]1To whom correspondence may be addressed. Email: giancarlo.ruocco{at}roma1.infn.it. [1]: #xref-corresp-1-1

Publisher's Note: "Thermodynamic formalism for transport coefficients with an application to the shear modulus and shear viscosity" [J. Chem. Phys. 1…

2017

Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero-shear viscosity

1983

Measurements of the viscosity coefficient η of solutions of polystyrene (Mw = 6.0 × 105 and 1.77 × 106) in trans-decalin (TD, θ solvent) and toluene (TL, good solvent) as function of shear rate (11−104 s−1), concentration (4.24−11.21 wt %), and temperature (10–50°C) are reported. As a new theoretically grounded method for the determination of the zero-shear viscosity η0 it is proposed to plot η as a function of . The intercepts of the straight lines obtained by this procedure give η0 in good agreement with directly measured values.

Consistency of Carbopol 971-P NF gels and influence of soluble and cross-linked PVP.

2002

A study is made of the polymerization process of polyacrylic acid, commercially known as Carbopol® 971 NF, assessing its consistency as a function of the degree of neutralization at pH values from 3 to 12, approximately. Percentage concentrations ranging from 0.1 to 1.4% (w/w) were studied. The gels obtained were non-Newtonian, and pseudoplastic. As concentration and pH rise, the consistency of the gels increase to a maximum, which appears between pH 6 and 8, allowing their use as vehicles in bioadhesive formulations for mucosal application. Over the increasing viscosity interval, functions were obtained to indicate the consistency of the gel as a function of pH and concentration. Since the…

Transition from thin- to thick-skinned tectonics and consequences for nappe formation: Numerical simulations and applications to the Helvetic nappe s…

2015

Abstract We use two-dimensional numerical simulations to study the deformation style and the formation of nappes during the shortening of basement–cover systems with half-grabens. We perform simulations with only linear and power-law viscous rheology, and also thermo-mechanical simulations with viscoelastoplastic rheology and temperature-dependent viscosities. The accumulated, area-averaged strain is calculated for the sediments, es, and for the basement, eb, to quantify the deformation style. The results show that the transition from thin-skinned dominated (es/eb > 1) to thick-skinned dominated (es/eb ≤ 1) deformation is controlled by two effective viscosity ratios: the ratio of viscosity …

Halloysite nanotubes as nanoreactors for heterogeneous micellar catalysis

2021

Abstract Hypothesis Electrostatic attractions between the anionic head group of sodium alkylsulphates and the positively charged inner surface of halloysite nanotubes (HNTs) drive to the formation of tubular inorganic micelles, which might be employed as nanoreactors for the confinement of non polar compounds in aqueous media. On this basis, sodium alkylsulphates/halloysite hybrids could be efficient nanocatalysts for organic reactions occurring in water. Experiments Sodium decylsulphate (NaDeS) and sodium dodecylsulphate (NaDS) were selected for the functionalization of the halloysite cavity. The composition, the structure and the surface charge properties of the hybrid nanotubes were dete…

Zero viscosity limit of the Oseen equations in a channel

2001

Oseen equations in the channel are considered. We give an explicit solution formula in terms of the inverse heat operators and of projection operators. This solution formula is used for the analysis of the behavior of the Oseen equations in the zero viscosity limit. We prove that the solution of Oseen equations converges in W1,2 to the solution of the linearized Euler equations outside the boundary layer and to the solution of the linearized Prandtl equations inside the boundary layer. © 2001 Society for Industrial and Applied Mathematics.

Über die Elementarreaktionen der radikalischen Polymerisation von Benzylmethacrylat

1973

Durch Kombination stationarer und instationarer Methodik (rotierender Sektor) werden die Absolutwerte der Geschwindigkeitskonstanten von Kettenwachstum und Kettenabbruch von Benzylmethacrylat unter dem Einflus verschieden viskoser Losungsmittel bestimmt. Die Radikalausbeute f hangt von der Viskositat des Losungssystems und der Art der Monomeren, dagegen nicht (oder fast nicht) von der Konzentration des Monomeren und der Geschwindigkeit der Radikalerzeugung ab. Daraus wird geschlossen, das ein merklicher Anteil von Zwillingsrekombinationen auserhalb des primaren Losungsmittelkafigs stattfindet. Die Geschwindigkeitskonstante kw des Kettenwachstums stimmt praktisch uberein mit der des Methylme…

1985

From the break-down in the viscosity and from the increase of the intensity of the scattered light, associated with the entrance into the two-phase region, the pressure dependence of the demixing temperature of solutions of PVC 37 000, PVC 75 000 and PVC 100 000 in phenetole and PVC 75 000 in o-xylene was measured up to 1 000 bar. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) The application of pressure increases the demixing temperatures of PVC in both solvents by about 1 K/100 bar. For a qualitative forecast of the pressure effects, the solubility parameter theory in combination with the corresponding states principle, and an empirical correlatio…