Activation energy in particle suspensions

Activation energy in particle suspensions F.J. Rubio A.I. Gómez 1 Departamento de Física Aplicada II, Universidad de Málaga, Málaga (Spain) 2 DECEM, Universidad de las Fuerzas Armadas, Sangolquí Assuming that the molar activation energy in a fluid the potential energy barrier require fluid depends on the actual size of the molecules, and the suspension increases the dissipation of energy when the system flows, expected that the viscosity of the suspension given temperature. The dependence of with the temperature can be Arrhenius equation,ln   constant,  is the molar activation energy for the vis temperature and  is the gas universal constant. decreases two effects are observed. First, to the red uction of the thermal agitation molecules of the liquid phase increase in the viscosity with the temperature that a higher viscosity value is due to a smaller f movement, and taking into account that the free suspension volume is limited the liquid fraction [2 ], it should be expected that the viscosity of the suspension sensitive to temperature than In this work the dependence on the temperature of the silica/glycol suspensions is shown a lower activation energy when the solid volume fraction increases, w been explained with a scheme that assumes that thermal energy absorption than the joining bonds among conclusion is that, for a given energy absorbed by the system solvent molecules. This study can be useful to understand the mechanisms that govern the differences in the activation energy values found be which many factors are connected with s [1] Briscoe B, Luckham P, Zhu S. solutions. J Appl Polym Sci [2] Shenoy AV. Rheology of filled polymer systems. [3] Alvarez MD, Canet W. vegetablebased infant purees Activation energy in particle suspensions F.J. Rubio -Hernández 1 , S. Murillo-González 1 , A.I. Gómez -Merino 1 , N.M. Páez-Flor 2 Departamento de Física Aplicada II, Universidad de Málaga, Málaga (Spain) DECEM, Universidad de las Fuerzas Armadas, Sangolquí (Ecuador) that the molar activation energy in a fluid is interpreted as a measure of the potential energy barrier require d for the molecular movement [1 ], the viscosity of a fluid depends on the actual size of the molecules, and the presence of solid particles increases the dissipation of energy when the system flows, the viscosity of the suspension is higher than that of the pure solvent at a The dependence of the viscosity of some silica/ glycol can be fitted using an empirical function analogous to the    ln , where is the viscosity,  is a system is the molar activation energy for the vis cous flow,  is the gas universal constant. When the temperature of the suspension are observed. First, larger aggregates of particles uction of the thermal agitation and, second, the number of links among the molecules of the liquid phase increases. These two effects give place to a higher with the temperature compared to the pure solvent. Assuming a higher viscosity value is due to a smaller f ree volume available for the molecular movement, and taking into account that the free suspension volume is limited ], it should be expected that the viscosity of the suspension sensitive to temperature than that of the pure solvent. dependence on the temperature of the viscosity is compared to that of the liquid media. The results have shown a lower activation energy when the solid volume fraction increases, w been explained with a scheme that assumes that the particle links are less sensitive to thermal energy absorption than the joining bonds among the solvent molecules. given mechanical energy applied to the system, the energy absorbed by the system is mainly used in the rupture of bonds between the This study can be useful to understand the mechanisms that govern the activation energy values found be tween samples connected with s ample composition [3]. Briscoe B, Luckham P, Zhu S. Rheological properties of poly (ethylene oxide) aqueous Polym Sci 70 (1998) 419-429. Shenoy AV. Rheology of filled polymer systems. Kluwer Acad Pub, 1999, The Netherlands. Alvarez MD, Canet W. Time-independent and timedependent rheological characterization based infant purees . J Food Eng 114 (2013) 449-464. Departamento de Física Aplicada II, Universidad de Málaga, Málaga (Spain) (Ecuador) interpreted as a measure of ], the viscosity of a solid particles in a increases the dissipation of energy when the system flows, therefore it is higher than that of the pure solvent at a glycol suspensions fitted using an empirical function analogous to the system -dependent is the absolute temperature of the suspension larger aggregates of particles are formed due the number of links among the place to a higher the pure solvent. Assuming ree volume available for the molecular movement, and taking into account that the free suspension volume is limited only to ], it should be expected that the viscosity of the suspension is less viscosity values of the that of the liquid media. The results have shown a lower activation energy when the solid volume fraction increases, w hich has the particle links are less sensitive to solvent molecules. Our mechanical energy applied to the system, the thermal is mainly used in the rupture of bonds between the This study can be useful to understand the mechanisms that govern tween samples of foods, in (ethylene oxide) aqueous Kluwer Acad Pub, 1999, The Netherlands. dependent rheological characterization of