Film Drainage Transition Temperatures and Phase Relations in the System Sodium Lauryl Sulfate, "Lauryl Alcohol and Water

Epstein, Morton B.; Wilson, Archie F.; Jakob, C. W.; Conroy, Lawrence E.; Ross, John

doi:10.1021/j150520a014

Cited by 35 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A significant amount of work in the literature discusses high surface viscosity and rigidity of aqueous films stabilized by prescribed mixtures of SDS (surface viscosity at saturation of approximately 2×10 −3 P) and long-alkyl chain alcohols (LCA), primarily dodecanol. 16 The mobile films obtained with surface-saturated SDS could become rigid by the careful addition of the LCA. This work suggested that, in the cases of mixtures, surface viscosity varied with surface composition.…”

Section: Rigid-and Mobile-surfaced Lamellae (Films)mentioning

confidence: 99%

"Tying up loose ends" – silicone surfactants as stabilizing agents for flexible polyurethane foam

2005

View full text Add to dashboard Cite

This paper is a tribute to the work of Dr. Michael J. Owen and colleagues in revealing the mechanism of the silicone surfactant-driven stabilization of flexible polyurethane foam. This work, performed at Midland Silicones (acquired by Dow Corning Corporation in 1967), was the inspiration for a body of experimental and theoretical research performed by the present authors in the mid-1990's. For flexible polyurethane foam, the surfactant is necessary to stabilize the liquid foamy mass before it hardens into an elastomeric sponge. Owen and coworkers demonstrated that in order to stabilize the foam the surfactant must (1) significantly lower the equilibrium surface tension of the liquid, (2) exhibit a dynamic surface tension within a narrow range of values, and (3) have an appreciable but low surface viscosity. The recent work of the authors has both validated these observations and extended their scope. They have modeled the stabilization process and have found that stability is the result of a delicate interplay of surface viscosity and elasticity which are functions of both structure and excess surface concentration of the surfactant. This modeling work was validated experimentally by investigating the drainage of model polyurethane thin liquid films ("soap films") containing silicone surfactants. The seminal nature of the work done by Owen and coworkers was reinforced by the authors' discovery that many of the original conclusions were validated by the recent work.

show abstract

Section: Rigid-and Mobile-surfaced Lamellae (Films)mentioning

confidence: 99%

"Tying up loose ends" – silicone surfactants as stabilizing agents for flexible polyurethane foam

2005

View full text Add to dashboard Cite

show abstract

“…In a series of experimental observations with solutions of different surfactants, these authors revealed several modes of foam film thinning and the terms "rigid" and "mobile" films were introduced for the two extreme types of behaviour. Epstein et al [3] pointed out that the surface rigidity is probably due to formation of "solid mixed surface layers" and emphasized the role of the dodecyl alcohol (C12OH) as an essential admixture which rigidifies the adsorption layers of sodium dodecyl sulfate (SDS) which was used as main surfactant in most experiments. Thus, the intricate link between the phase state of surfactant adsorption layers and the film thinning behaviour was recognized for the first time.…”

Section: Introduction -Role Of Surface "Rigidity" In Foam Studiesmentioning

confidence: 99%

Surface phase transitions in foams and emulsions

Denkov

Cholakova

2019

Current Opinion in Colloid & Interface Science

View full text Add to dashboard Cite

Surface phase transitions in surfactant adsorption layers are known to affect the dynamic properties of foams and to induce surface nucleation in freezing emulsion drops. Recently, these transitions were found to play a role in several other phenomena, opening new opportunities for controlling foam and emulsion properties. This review presents a brief outlook of the emerging opportunities in this area. Three topics are emphasized: (1) The use of surfactant mixtures for inducing phase transitions on bubble surfaces in foams; (2) The peculiar properties of natural surfactants saponins which form extremely viscoelastic surface layers; and (3) The main phenomena in emulsions, for which the surface phase transitions areimportant. The overall conclusion from the reviewed literature is that surface phase transitions could be used as a powerful tool to control many foam and emulsion properties, but we need deeper understanding of the underlying phenomena to explore fully these opportunities.

show abstract

“…Um filme de espuma pode ser desestabilizado se exposto a flutuações térmicas 24,25 ; sob redução de temperatura, sua elasticidade pode ser reduzida, enquanto a elevação de temperatura pode provocar dessorção do agente espumante da interface e diminuição da viscosidade e da resistência superficial. A uma temperatura mais elevada, a evaporação da água é acelerada, estimulando a desidratação do filme e induzindo, para compensar a diminuição da tensão superficial resultante, o seu estiramento e a aproximação das camadas de adsorção.…”

Section: Ciência De Espumasunclassified

Ciência de espumas - aplicação na extinção de incêndios

Figueredo¹,

Ribeiro²,

Sabadini³

1999

Quím. Nova

View full text Add to dashboard Cite

Recebido em 31/3/98; aceito em 1/6/98 SCIENCE OF FOAMS -APPLICATION IN FIRE-FIGHTING.The structural characteristics of foams are responsible for a broad range of applications of this system. Foams produced by aqueous solutions of surfactant concentrates are used in fire-fighting due to their special properties as extinguishing agents. In the present paper we discuss the main aspects involved in fire-fighting, based on some properties of foams. Thermal and chemical stability, good wetting of surfaces, cooling effect by water drained from the bubbles, isolation of the air from the burning surface and suppression of flammable vapors are some of the factors involved in the extinguishment of fire by foams.Keywords: foam; fire-fighting; perfluorinated surfactants. DIVULGAÇÃO INTRODUÇÃOHá alguns anos temos estudado espumas usadas em incêndi-os em líquidos inflamáveis (incêndios classe B). O principal enfoque do nosso estudo envolve o emprego de polímeros redutores de atrito hidrodinâmico em espumas extintoras, aplicação potencial no campo da extinção de incêndios. Agentes redutores do atrito hidrodinâmico 1,2 produzem significativa redução na energia necessária para o deslocamento de um fluido, atribuindo maior eficiência e flexibilidade ao combate. Em nosso trabalho, contamos com a colaboração de um dos principais grupos técnicos que lidam com a extinção de incêndios, o PAM (Plano de Auxílio Mútuo de Paulínia), que congrega algumas indústrias próximas à Refinaria do Planalto da Petrobrás (Replan). Pretendemos divulgar neste artigo processos envolvidos na extinção de incêndios por espumas, com uma breve referência à ciência de espumas. CIÊNCIA DE ESPUMASAs espumas são sistemas termodinamicamente instáveis que apresentam uma estrutura tridimensional constituída de células gasosas envolvidas por um filme líquido contínuo. Essa estrutura origina-se do agrupamento de bolhas geradas ao se dispersar um gás em um líquido que contenha agentes espumantes, como surfatantes solúveis ou impurezas. Moléculas do surfatante difundem-se na solução em direção à interface gás-líquido formando uma monocamada adsorvida que estabiliza a bolha de gás e retarda sua rápida coalescência. A destruição das bolhas é termodinamicamente favorável pois provoca redução da elevada área superficial da espuma e expansão do gás contido nas células e, consequentemente, redução da energia livre da espuma.O processo de dispersão do gás pode ser desencadeado por agitação ou batimento do líquido e por borbulhamento do gás no líquido, e influi diretamente sobre as características da espuma. Espumas formam-se também quando há redução de pressão ou aumento de temperatura em soluções supersaturadas de gás. Pelo borbulhamento, é possível estimar o tamanho das cé-lulas geradas através da dimensão do borbulhador 3 . A uniformidade na distribuição e no tamanho de suas bolhas, grau de dispersidade, está sujeita às irregularidades do dispositivo através do qual o gás é introduzido 4 . Entretanto, fatores como velocidade do gás e concentração de surfatante nas células e...

show abstract

Film Drainage Transition Temperatures and Phase Relations in the System Sodium Lauryl Sulfate, "Lauryl Alcohol and Water

Cited by 35 publications

References 0 publications

"Tying up loose ends" – silicone surfactants as stabilizing agents for flexible polyurethane foam

"Tying up loose ends" – silicone surfactants as stabilizing agents for flexible polyurethane foam

Surface phase transitions in foams and emulsions

Ciência de espumas - aplicação na extinção de incêndios

Contact Info

Product

Resources

About