| 1. |
- Allouche, Joachim, et al.
(författare)
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Simultaneous Conductivity and Viscosity Measurements as a Technique To Track Emulsion Inversion by the Phase-Inversion-Temperature Method
- 2004
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 20:6, s. 2134-2140
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Tidskriftsartikel (refereegranskat)abstract
- Two kinds of transitions can occur when an emulsified water-oil-ethoxylated nonionic surfactant system is cooled under const. stirring. At a water-oil ratio close to unity, a transitional inversion takes place from a water-in-oil (W/O) to an oil-in-water (O/W) morphol. according to the so-called phase-inversion-temp. method. At a high water content, a multiple W/O/W emulsion changes to a simple O/W emulsion. The continuous monitoring of both the emulsion cond. and viscosity allows the identification of several phenomena that take place during the temp. decrease. In all cases, a viscosity max. is found on each side of the three-phase behavior temp. interval and correlates with the attainment of extremely fine emulsions, where the best compromise between a low-tension and a not-too-unstable emulsion is reached. The studied system contains Polysorbate 85, a light alkane cut oil, and a sodium chloride brine. All transitions are interpreted in the framework of the formulation-compn. bidimensional map.
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| 2. |
- Allouche, Joachim, et al.
(författare)
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Single- and Two-Step Emulsification To Prepare a Persistent Multiple Emulsion with a Surfactant-Polymer Mixture
- 2003
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 42:17, s. 3982-3988
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Tidskriftsartikel (refereegranskat)abstract
- The regions corresponding to different emulsion morphol. occurrences have been clearly identified on a bidimensional formulation-compn. map. Multiple emulsions spontaneously form when there is a conflict between the formulation and compn. effects. In such systems the most external emulsion is found to be unstable when the formulation effect is produced by a single surfactant. The use of a proper surfactant-polymer mixt. allows one to strongly inhibit the mass transfer and to considerably lengthen the equilibration between interfaces. As a consequence, the multiple emulsion can be stable enough to be used in encapsulation and controlled-release applications. The area where multiple emulsions occur and their characteristics (cond. and amt. of encapsulated external phase) are reported for a system contg. a sorbitan ester lipophilic surfactant and a diblock poly(ethylene oxide)-poly(propylene oxide) hydrophilic polymer, as a function of the formulation and compn., for a single-step process in which a specific amt. of mech. energy (stirring) is supplied. An increase in the oil viscosity is found to alter the map and to modify the multiple emulsion characteristics. The application of the results to emulsion-making technol. is discussed.
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| 3. |
- Philippe, Bertrand, et al.
(författare)
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Nanosilicon Electrodes for Lithium-Ion Batteries : Interfacial Mechanisms Studied by Hard and Soft X-ray Photoelectron Spectroscopy
- 2012
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 24:6, s. 1107-1115
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Tidskriftsartikel (refereegranskat)abstract
- Largely based on its very high rechargeable capacity, silicon appears as an ideal candidate for the next generation of negative electrodes for Li-ion batteries. However, a crucial problem with silicon is the large volume expansion undergone upon alloying with lithium, which results in stability problems. Means to avoid such problems are largely linked to the understanding of the interfacial chemistry during charging/discharging. This is especially of great importance when using nanometric silicon particles. In this work, the interfacial mechanisms (reaction of surface oxide, Li-Si alloying process, and passivation layer formation) accompanying lithium insertion/extraction into Si/C/CMC composite electrodes have been scrutinized by Xray photoelectron spectroscopy (XPS). A thorough nondestructive depth-resolved analysis was carried out by using both soft X-rays (100-800 eV) and hard X-rays (2000-7000 eV) from two different synchrotron facilities compared with in-house XPS (1487 eV). The unique combination utilizing hard and soft X-ray photoelectron spectroscopy accompanied with variation of the analysis depth allowed us to access interfacial phase transitions at the surface of silicon particles as well as the composition and thickness of the SEI (electrode/electrolyte interface layer).
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| 4. |
- Tyrode, Eric, et al.
(författare)
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Emulsion Catastrophic Inversion from Abnormal to Normal Morphology. 4. Following the Emulsion Viscosity during Three Inversion Protocols and Extending the Critical Dispersed-Phase Concept
- 2005
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 44:1, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Three protocols are tested to invert an abnormal emulsion into a normal one: a dynamic process with continuous addn. of an internal phase, continuous stirring of a given emulsion with no addn. of an internal phase, and the combination of the previous ones, i.e., a standstill dynamic process in which the addn. of an internal phase is interrupted at some time and then followed by continued stirring. In situ follow-up of both cond. and viscosity data in a rheomixer vessel provides complementary information to corroborate the crit. dispersed-phase concept as a condition for the inversion to take place in all cases. Some applications are discussed. [on SciFinder (R)]
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