The chemico-physical properties of liquid films (LF) play an important role in different natural phenomena and technologies, particularly those concerned with emulsions and foams. Today different surface active species are utilised to stabilise the LF, such as surfactants, proteins, polymers and solid particles, which strongly affects the surface tension and the dilational rheology of the film interfaces. The behaviour of LF results however quite differently from that of single interfaces, due to its volume finiteness and small thickness, which limits the exchange of molecules with the bulk and makes the adsorption layers at the two sides of the films to interact. Based on an application of Capillary Pressure tensiometry, the Liquid Film Tensiometer (LIFT) has been conceived as an instrument for an accurate investigation of spherical films that will provide the measurement of dynamic film tension and dilational film rheology, associated with measurements of the thickness evolution. Here we will provide an overview of the technique with some exemplifications. The LIFT concept has been adopted to develop with the support of the Italian Space Agency a special apparatus for the investigation of LF onboard the International Space Station. Weightlessness conditions are in fact useful to study the properties of the film only subject to capillary drainage and will also allow investigating these properties in the wet film regime. Such instrument will also include enhanced optical techniques for the simultaneous measurement of the film thickness. References: 1. Y.H. Kim, K Koczo, D. T. Wasan, J. Colloid Interface Sci.,187 (1997) 29 2. V.I. Kovalchuk; J. Krägel, A.V. Makievski, F. Ravera, L. Liggieri, G. Loglio, V.B. Fainerman, R. Miller, J. Colloid Interface Sci., 280 (2004) 498. 3. R. Gabrieli, G. Loglio, P. Pandolfini , A. Fabbri, M. Simoncini, V.I. Kovalchuk, B.A. Noskov, R. Miller, F. Ravera, L. Liggieri. Spherical Cap-Shaped Emulsion Films: Thickness Evaluation at the Nanoscale Level by the Optical Evanescent Wave Effect. Colloids and Surfaces A, submitted 2012.
The investigation of liquid films by the LIFT Tensiometer
Libero Liggieri;Francesca Ravera;Eva Santini;Michele Ferrari;
2012-01-01
Abstract
The chemico-physical properties of liquid films (LF) play an important role in different natural phenomena and technologies, particularly those concerned with emulsions and foams. Today different surface active species are utilised to stabilise the LF, such as surfactants, proteins, polymers and solid particles, which strongly affects the surface tension and the dilational rheology of the film interfaces. The behaviour of LF results however quite differently from that of single interfaces, due to its volume finiteness and small thickness, which limits the exchange of molecules with the bulk and makes the adsorption layers at the two sides of the films to interact. Based on an application of Capillary Pressure tensiometry, the Liquid Film Tensiometer (LIFT) has been conceived as an instrument for an accurate investigation of spherical films that will provide the measurement of dynamic film tension and dilational film rheology, associated with measurements of the thickness evolution. Here we will provide an overview of the technique with some exemplifications. The LIFT concept has been adopted to develop with the support of the Italian Space Agency a special apparatus for the investigation of LF onboard the International Space Station. Weightlessness conditions are in fact useful to study the properties of the film only subject to capillary drainage and will also allow investigating these properties in the wet film regime. Such instrument will also include enhanced optical techniques for the simultaneous measurement of the film thickness. References: 1. Y.H. Kim, K Koczo, D. T. Wasan, J. Colloid Interface Sci.,187 (1997) 29 2. V.I. Kovalchuk; J. Krägel, A.V. Makievski, F. Ravera, L. Liggieri, G. Loglio, V.B. Fainerman, R. Miller, J. Colloid Interface Sci., 280 (2004) 498. 3. R. Gabrieli, G. Loglio, P. Pandolfini , A. Fabbri, M. Simoncini, V.I. Kovalchuk, B.A. Noskov, R. Miller, F. Ravera, L. Liggieri. Spherical Cap-Shaped Emulsion Films: Thickness Evaluation at the Nanoscale Level by the Optical Evanescent Wave Effect. Colloids and Surfaces A, submitted 2012.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
