Extensional viscosity measurements of concentrated emulsions with the use of the opposed nozzles device

Abstract

-This paper presents results of experimental studies on the apparent extensional viscosity of emulsions. The apparent extensional viscosity measurements were carried out with the use of a customized rheometer which utilizes stagnation flow between two opposing nozzles. Apparent extensional viscosity was determined for emulsions containing 60, 70 and 74 vol.% of dispersed phase. The emulsions were produced using a homogenizer equipped with different dispersing endings that resulted in emulsions characterized by different droplet sizes. The experimental results show that the value of apparent extensional viscosity of the emulsion is significantly influenced by the droplet size and by the concentration of dispersed phase. Apparent extensional viscosity as well as shear viscosity of the emulsions increases with the increase of the dispersed phase concentration and with the decrease of the droplet diameter. It has also been observed that the decrease in the diameter of droplets increases the ratio of the apparent extensional viscosity to the shear viscosity, known as the Trouton ratio.

Aeration of Liquid‐Liquid Systems Using Various Agitators in a Mixer Equipped with a Membrane Diffuser

“…single liquid phase) are in the chemical engineering curriculum 57, 58, it was pointed out that there is a lack of description of physical data of L‐L systems that influence G‐L‐L operations 23. From the point of equipment design, the physical characteristics of L‐L dispersions or emulsions that play a significant role in designing processes in mechanically stirred tanks 59, in membrane‐based emulsifications 60, 61 or in sieve emulsification mixer 62 are as follows: ratio between the liquid height and the tank diameter, rotational speed of the stirrer, ratio of stirrer diameter to tank diameter, density, interfacial tension, viscosity (either shear or extensional viscosity 63, 64), and feeding/recirculation rates of immiscible liquids. Although these parameters are studied quite intensively for L‐L systems, there is very limited information about the influence of such parameters when G‐L‐L systems in stirred tanks are set up 23, 65; therefore, scale‐up of multiphase bioprocesses is extremely difficult 56.…”

Development of a Rheology Die and Flow Characterization of Gas-Containing Polymer Melts

“…One way of comparing elongational and shear viscosity is to use the Trouton ratio (i.e., the ratio of elongational viscosity to shear viscosity). As stated in the literature, the Trouton ratio is always equal to 3 for Newtonian fluids [ 29 , 30 ]. However, it was shown by Binding et al [ 31 ] and Bach et al [ 32 ] that the ratios for polymeric materials are larger by a factor of 10–100.…”

The Bioactivity and Physicochemical Properties of Emulsions Based on Tamanu, Moringa, and Inca Inchi Oils

“…In addition, rheological tests of the obtained emulsions were carried out according to the methodology validated and described by Różańska et al [ 20 ]. Briefly, the emulsion samples were placed in a water bath for a period of 60 min at 25 ± 0.5 °C.…”

“…In addition, rheological tests of the obtained emulsions were carried out according to the methodology validated and described by Ró ża ńska et al [20]. Briefly, the emulsion samples were placed in a water bath for a period of 60 min at 25 ± 0.5 • C. Rheological assessments under shear flow conditions were conducted employing a Physica MCR302 rheometer manufactured by Anton Paar (Austria) with a thermostatic unit (providing the heated fluid for the heating jacket).…”