Rheological Behaviour of Saturated Polyglycolysed Glycerides

Abstract

Seven saturated polyglycolysed glycerides (Gelucires) of melting points varying from 42 to 53 degrees C and hydrophilic-lipophilic balance values from 2 to 14 were selected. Their rheological behaviour was determined by adjustment of the flow curves to the Ostwald power-law and by statistical assessment of the flow index. The flow of Gelucires was slightly shear thickening. This shear thickening rose when the temperature and the lipophilic specificity of the Gelucire increased. This behaviour accounted for a reorganization of the particles under the shear which became easier when the temperature increased and when the degree of condensation of the polyethylene glycol chains decreased with lipophilicity of the Gelucires.

Temperature behaviour of viscous flow with proteins

“…This method was successfully applied to many liquids when the viscosity measurements were conducted in a relatively narrow range of temperatures (Hayakawa et al 1991;Bourret et al 1994;Lopez da Silva et al 1994;Jauregui et al 1995;de Paula and Rodrigues 1995;Kar and Arslan 1999;de Vasconcelos et al 2000;Desbrieres 2002;Kamimura et al 2006;Durand 2007;Knoben et al 2007). Linear dependence of lnη on T -1 means that the activation energy is constant.…”

“…The pre-exponential factor A is considered to be independent or nearly independent of temperature. The above equation is still widely used for different liquids such as solutions of polysaccharides (Lopez da Silva et al 1994;Jauregui et al 1995;de Paula and Rodrigues 1995;Kar and Arslan 1999;de Vasconcelos et al 2000;Desbrieres 2002;Durand 2007), proteins (Tiffany and Koretz 2002), supramolecular polymers (Knoben et al 2007), colloidal suspensions (Gun'ko et al 2006) and others (Hayakawa et al 1991;Bourret et al 1994;Kamimura et al 2006;Magerramov et al 2007). A very convenient way of data presentation in this case is plotting the viscosity versus T -1 in a ln-normal plot.…”

A comparison of the activation energy of viscous flow for hen egg-white lysozyme obtained on the basis of different models of viscosity for glass-forming liquids

“…This method was successfully applied for many liquids in the case when the viscosity measurements were conducted in a relatively narrow range of temperatures (Hayakawa et al, 1991;Bourret et al, 1994;Lopez da Silva et al, 1994;Jauregui et al, 1995;de Paula & Rodrigues, 1995;Kar & Arslan, 1999;de Vasconcelos et al, 2000;Desbrieres, 2002;Durand, 2007;Knoben et al, 2007). In our case, viscosity measurements were made in a broad range of temperatures.…”

Effect of Formulation on the Rheology of Theophylline Compound Suspensions in Gelucires

“…Influence of temperature In the case of diprophylline suspension at 25% w/w in Gelucire 50102, increase of the water-bath temperature resulted in a logical decrease in apparent viscosity ( Table 1). An Arrheniustype relationship could be applied in this case as was previously done for pure Gelucires (Bourret et al 1994). To ensure that suspensions were sufficiently fluid and to preserve Gelucire stability, the water-bath temperature was fixed at 80°C for Gelucire 50102 (mp + 30°C for all Gelucires).…”