Stabilization of bubbles and foams

Murray, Brent S.

doi:10.1016/j.cocis.2007.07.009

Cited by 288 publications

(201 citation statements)

References 107 publications

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“…Surface hydrophobization can be accomplished by choosing amphiphiles with functional groups that react with the surface hydroxyl groups. Pyrogallol groups can efficiently adsorb on oxide surfaces via ligand exchange reactions [14,16] and thus can be used with a short hydrocarbon tail to modify the surfaces of particles with intermediate IEPs.…”

Section: Zeta Potential and In Situ Hydrophobizationmentioning

confidence: 99%

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Porous Ceramics

Sarkar¹,

Kim²

2015

Advanced Ceramic Processing

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The unique chemical composition and microstructure of porous ceramics enable the ceramic products used in a number of applications such as filtration of molten metals and hot corrosive gases, high-temperature thermal insulation, support for catalytic reactions, filtration of diesel engine exhaust gases, etc. These applications take advantage of special characteristics of porous ceramics such as low thermal mass, low thermal conductivity, controlled permeability, high surface area, low density, and high specific strength. In this chapter, we emphasize on direct foaming method, a simple and versatile approach that allows fabrication of porous ceramics with tailored microstructure along with distinctive properties. Foam stability is achieved upon controlled addition of amphiphiles to the colloidal suspension, which induce in situ hydrophobization, allowing the wet foam to resist coarsening upon drying and sintering.

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Section: Zeta Potential and In Situ Hydrophobizationmentioning

confidence: 99%

“…Changes in open and closed porosity, pores' size distribution, and pores' morphology can greatly affect a material's properties. These microstructural features are highly influenced by the processing route used to produce the porous material [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Porous Ceramics

Sarkar¹,

Kim²

2015

Advanced Ceramic Processing

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“…For example, coalescence may be slowed by repulsive forces between the surfactant monolayers adsorbed to either side of the (continuous) phase separating bubbles or drops. Ionic surfactants, for example, introduce electrostatic repulsions (1,2,5), whereas nonionic surfactants (e.g., polymers, proteins, or particles) provide steric barriers against coalescence (7)(8)(9). Moreover, Marangoni stresses arise when compressional or dilatational deformations drive gradients in surfactant concentration (and thus surface tension).…”

mentioning

confidence: 99%

Surface shear inviscidity of soluble surfactants

Zell

Nowbahar

Mansard

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

116

123

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Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 10 3 -10 4 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high-and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants.S urfactants facilitate the formation of foams and emulsions by reducing surface tension, thereby lowering the energy required to create excess surface area (1-3). These multiphase materials, however, are thermodynamically unstable, and coarsen through bubble or drop coalescence, as well as diffusive exchange between bubbles or drops (1, 4-6). Surfactants can additionally be used to control this coarsening rate, with effective foaming surfactants retarding coalescence, and defoamers speeding it. For example, coalescence may be slowed by repulsive forces between the surfactant monolayers adsorbed to either side of the (continuous) phase separating bubbles or drops. Ionic surfactants, for example, introduce electrostatic repulsions (1, 2, 5), whereas nonionic surfactants (e.g., polymers, proteins, or particles) provide steric barriers against coalescence (7-9). Moreover, Marangoni stresses arise when compressional or dilatational deformations drive gradients in surfactant concentration (and thus surface tension). The resulting dilatational surface elasticity resists surface area changes, slowing drainage and rupture of the thin fluid films between adjacent bubbles (4, 5, 10-13).Additionally, surfactant monolayers may exhibit nontrivial rheological responses. For example, the surface shear viscosity η S gives the excess viscosity associated with shearing deformations within the 2D surfactant monolayer. Because surfactant interfaces are inherently compressible, they may exhibit a surface dilatational viscoelasticity η D *, in addition to η S *, even under small-amplitude deformations. This contrasts with incompressible Newtonian liquids, which are well-described by a single scalar viscosity. Moreover, surface shear and dilatational viscosities need not have equal (14), or even compara...

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“…A significant factor in this arrangement is the chemical nature of the egg white and LMS and the type of the oil-water and water-to-air interfaces [5]. Competitive adsorption in multicomponent food systems is complicated by the presence of several phases, including fat crystals [6].…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Development of a model of steric stabilization of the air-nut semi-finished product structure

Горальчук

Гринченко

Gubsky

et al. 2017

EEJET

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Розроблено теоретичну модель сте-ричної стабілізації структури повітряно-горіхового напівфабрикату, шляхом додат-кового введення дистильованих моногліце-ридів та натрій-карбоксиметилцелюлози. Експериментально доведено, що введення низькомолекулярних поверхнево-активних речовин в олію забезпечує гідрофілізацію жирової фази та зменшує десорбцію білка з бульбашок повітря. Введення натрій-кар-боксиметилцелюлози забезпечує підвищення в'язкості, зменшує флотацію твердих час-тинок горіхів, забезпечує стійкість системи до перемішування Ключові слова: напівфабрикат повітряно-горіховий, стерична стабілізація, флотація, піноутворююча здатність, стійкість піни, міжфазні шари Разработана теоретическая модель сте-рической стабилизации структуры воздуш-но-орехового полуфабриката путем допол-нительного введения дистиллированных моноглицеридов и натрий-карбоксиметил-целлюлозы. Экспериментально доказано, что введение низкомолекулярных поверх-ностно-активных веществ в масло обеспе-чивает гидрофилизацию жировой фазы и уменьшает десорбцию белка из пузырьков воздуха. Введение натрий-карбоксиметил-целлюлозы обеспечивает повышение вязко-сти, уменьшает флотацию твердых частиц орехов, обеспечивает устойчивость систе-мы к перемешиванию Ключевые слова: полуфабрикат воздуш-но-ореховый, стерическая стабилизация, флотация, пенообразующая способность, устойчивость пены, межфазные слои UDC 664.64

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Stabilization of bubbles and foams

Cited by 288 publications

References 107 publications

Porous Ceramics

Porous Ceramics

Surface shear inviscidity of soluble surfactants

Development of a model of steric stabilization of the air-nut semi-finished product structure

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