Relaxation Processes and Dilational Rheology of Adsorbed Layers in Relation to the Stability of Fluid Disperse Systems (Abstract/Poster in atti di convegno)

Type
Label
  • Relaxation Processes and Dilational Rheology of Adsorbed Layers in Relation to the Stability of Fluid Disperse Systems (Abstract/Poster in atti di convegno) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • Ravera F.; Santini E.; Ferrari M.; Liggieri L.; Miller R. (2006)
    Relaxation Processes and Dilational Rheology of Adsorbed Layers in Relation to the Stability of Fluid Disperse Systems
    in IACIS - 12th Conference on Surface and Colloid Science, Beijin, China
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Ravera F.; Santini E.; Ferrari M.; Liggieri L.; Miller R. (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note
  • IACIS - 12th Conference on Surface and Colloid Science (Beijin, China, 15-20 October 2006). (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto
  • The properties of the single liquid- fluid interfaces, especially concerning their dynamic aspects, play an important role in the process of coalescence of bubbles and drops in emulsions and foams. For this reason a deep knowledge of such properties and of their relation with the characteristics of the respective fluid disperse systems is of fundamental and practical interest. In this context it is important to consider that the dynamic characteristics of the interfacial layers, like dynamic interfacial tension and dilational visco-elasticity as a function of the frequency, are closely related to the surfactant adsorption mechanisms and to the relaxation processes occurring in the adsorbed layer, as it has been shown recently in many theoretical and experimental works. In this work interfacial tension and dilational visco-elasticity experimental data are presented versus frequency and as a function of the surfactant concentration. The studied systems were polyoxyethylene glycol ethers (CiEj) at water/air and water/hexane interfaces and Span80 at paraffin oil/water interface. The latter has been chosen, as model systems for emulsion stability studies, because allows w/o emulsions to be obtained, while CiEj are also used as stabilizer of foam films. The dilational visco-elasticity have been measured by two oscillating drop techniques: one based on the elaboration of the drop profile (Profile Analysis Tensiometer-Sinterface) and the other based the direct measurement of capillary pressure (CPT-Capillary Pressure Tensiometer). The coupling of these two methods allows for measurements in a larger frequency range spanning over about 5 decades. The data obtained are interpreted in the light of the recent model developments which relate dilational rheology to the dynamic interfacial processes involved in adsorption kinetics. This also allows the behaviour at high frequency of the same systems to be foreseen, which is expected to influence emulsion and foam stability. (literal)
Titolo
  • Relaxation Processes and Dilational Rheology of Adsorbed Layers in Relation to the Stability of Fluid Disperse Systems (literal)
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