Polydimethylsiloxane (PDMS)-based antifoams

Bergeron, Vance; Cooper, Philip H.; Fischer, Christian B.; Giermańska, Joanna; Langévin, D.; Pouchelon, A.

doi:10.1016/s0927-7757(96)03774-0

Cited by 114 publications

(154 citation statements)

References 32 publications

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“…Thus our paper sheds light on the mechanisms at play during the perforation-driven destabilization of a liquid sheet. A similar Marangoni-driven mechanism has also been proposed as a possible mode of action of oilbased antifoams [17,18], but to our knowledge has never been experimentally evidenced.We used dilute oil-in-water emulsions. The oil phase comprises methyllaurate (Sigma-Aldrich) and a mixture of surfactants (provided by Solvay) of type C n EO 3 , with C n a hydrocarbon chain with n carbon atoms and EO 3 a chain of three ethylene oxide units (CH 2 CH 2 O).…”

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confidence: 59%

Bursting of Dilute Emulsion-Based Liquid Sheets Driven by a Marangoni Effect

2015

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We study the destabilization mechanism of thin liquid sheets expanding in air and show that dilute oil-in-water emulsion-based sheets disintegrate through the nucleation and growth of holes that perforate the sheet. The velocity and thickness fields of the sheet outside the holes are not perturbed by holes and hole opening follows a Taylor-Culick law. We find that a pre-hole, which widens and thins out the sheet with time, systematically precedes the hole nucleation. The growth dynamics of the pre-hole follows the law theoretically predicted for a liquid spreading on another liquid of higher surface tension due to Marangoni stresses. Classical Marangoni spreading experiments quantitatively corroborate our findings.The destabilization of free liquid films is of great importance for aerosol dispersions, and is involved in many practical situations [1,2] [6], and dilute oil-in-water emulsions [7]. However, despite its relative ubiquity, the bursting of liquid sheets through perforation events have not yet been carefully investigated nor modeled. The occurrence of perforation events in a spray directly decreases the fraction of small drops issued from the spray [8] as illustrated in the case of dilute emulsions, which are prone to induce the bursting of liquid sheets [7]. Dilute emulsions are also recognized as anti-drift adjuvants [8][9][10][11] and therefore commonly used as carrier fluids for pesticides delivery. Controlling the perforation processes would therefore allow one to finely tune the size distribution of drops issued from sprays, a goal of uttermost importance in many industrial processes. In this optics, a physical description of the mechanisms at play in perforation processes is desired. The commonly invoked conditions for perforation include a dewetting of inclusions by the fluid and an inclusion diameter equal to, or larger than, the thickness of the liquid sheet, so that inclusions cause perforation by puncturing both interfaces of the sheet [3]. But, to the best of our knowledge, those conditions have never been confronted to robust experimental facts. To unambiguously clarify the physical mechanisms at play, rationale experiments on individual perforation events are therefore required.In this Letter, we investigate the perforation mechanisms of an emulsion-based free liquid sheet issued from a single-drop experiment; resulting from the impact of one drop of fluid onto a small target [12][13][14]. During the sheet expansion, holes nucleate and grow. We show that each perforation event is preceded by the formation of a pre-hole that thins out the sheet and widens with time. We demonstrate that the pre-hole growth is governed by a Marangoni effect. The entry of emulsion oil droplets at the air/water interface leads to a spreading of the oil due to a surface tension gradient stress. This stress is counterbalanced by a viscous stress that drags the subsurface fluid, whose flow causes a local film thinning which ultimately lead to the rupture of the film. We show that the growth kinetics of pre-holes ...

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confidence: 59%

Bursting of Dilute Emulsion-Based Liquid Sheets Driven by a Marangoni Effect

2015

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“…However, the most common and robust method to control foam is to add antifoaming and defoaming agents [3,[71][72][73][74][75][76]. For foaming oils, these products are usually silicone oils, particularly PolyDiMethylSiloxane (PDMS) or fluorosilicone products for the most severe cases.…”

Section: Antifoaming and Defoaming In The Petroleum Industrymentioning

confidence: 99%

“…This can be answered by considering the basic mechanisms and physical chemical criteria that leads to foam destruction. The model used to explain aqueous foam destruction by insoluble oils leads to evaluate three coefficients based on thermodynamic criteria for capillary stability of foam lamellae; the entering coefficient E, the spreading coefficient S and the bridging coefficient B as given by Equations (1) to (3), which are functions of the various surface energies of the system [14,71]:…”

Section: Antifoaming and Defoaming In The Petroleum Industrymentioning

confidence: 99%

“…The primary condition needed to rupture the foamfilm is that the antifoaming droplets must enter the gas/liquid interface [71], which is met when the entering coefficient is positive (E a/i > 0). Once entry is achieved, two mechanisms can lead to rupture, fluid entrainment and/or pinch-off ( -fluid entrainment: the antifoam droplet spreads over the gas/liquid interface, (S a/i !…”

Section: Antifoaming and Defoaming In The Petroleum Industrymentioning

confidence: 99%

“…The "slow antifoam" is the one which first leaves the foam films and destroys the foam after entering the walls of the Plateau Borders. This entry barrier has been defined as a function of the critical capillary pressure or the disjoining pressure [71,76,[78][79] where the threshold value of the entry barrier is somewhere between 15 and 20 Pa, which separates the fast antifoam region from the slow one.…”

Section: Antifoaming and Defoaming In The Petroleum Industrymentioning

confidence: 99%

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Non-Aqueous and Crude Oil Foams

Blázquez

Emond

Schneider

et al. 2013

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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D o s s i e rRe´sume´-Mousses non aqueuses et mousses pe´trolie`res -Les mousses produites a`partir de syste`mes non aqueux sont moins fre´quentes que les mousses a`base d'eau, mais elles jouent un roˆle important dans de nombreuses applications et proce´de´s industriels. La faible tension de surface des liquides a`base d'hydrocarbures limite l'adsorption des agents de surface classiques et par conse´quent diffe´rents compose´s et me´thodes doivent eˆtre conside´re´s afin de ge´ne´rer et de stabiliser les mousses a`base d'huile. De meˆme, le cassage des mousses non aqueuses inde´sirables ne´cessite des conside´rations spe´cifiques a`ces syste`mes. Les mousses de pe´trole pre´sentent un inte´reˆt particulier de par leur complexite´en raison de la grande varie´te´des compose´s et des gaz qui peuvent les constituer. Nous pre´sentons dans cet article un aperc¸u des principaux me´canismes reconnus comme importants pour la stabilite´des mousses non aqueuses avec une conside´ration toute particulie`re pour les mousses de pe´trole brut.Abstract -Non-Aqueous and Crude Oil Foams -Foams produced from non-aqueous media are less common than water-based foams but they play an important role in many industries and engineering processes. The low surface tension of hydrocarbon fluids limits the adsorption of common surface activity substances and different compounds and methods must be considered to generate and stabilize oil-based foam. Likewise, the destruction of unwanted non-aqueous based foam requires specific considerations not found with aqueous systems. Of particular interest are petroleum-based foams, which are highly complex due to the wide variety of compounds and gases that can be found. We provide an overview of the major mechanisms known to be important for non-aqueous foam stability with a spotlight on crude-oil foams.

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Silicones

Butts

Cella

Wood

et al. 2002

Kirk-Othmer Encyclopedia of Chemical Technology

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Silicon are a class of materials with unique properties that make them useful in a variety of applications of commercial interest and support a thriving global industry. This article updates a comprehensive survey of the chemistry and technology of silicones last published in Kirk‐Othmer Encyclopedia of Chemical Technology in 1997. The update contains more than 235 references not cited in the previous version and includes literature published through 2001. A new section dealing with fiber finishing applications has been included in the current version. The review provides an excellent primary reference for this interesting area of chemistry and technology.

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Polydimethylsiloxane (PDMS)-based antifoams

Cited by 114 publications

References 32 publications

Bursting of Dilute Emulsion-Based Liquid Sheets Driven by a Marangoni Effect

Bursting of Dilute Emulsion-Based Liquid Sheets Driven by a Marangoni Effect

Non-Aqueous and Crude Oil Foams

Silicones

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