scholarly journals A Review on Bubble Stability in Fresh Concrete: Mechanisms and Main Factors

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1820 ◽  
Author(s):  
Xiaohui Zeng ◽  
Xuli Lan ◽  
Huasheng Zhu ◽  
Haichuan Liu ◽  
Hussaini Abdullahi Umar ◽  
...  
Keyword(s):  
Surface Tension ◽  
Influencing Factors ◽  
Fresh Concrete ◽  
Foam Stability ◽  
Current Trend ◽  
Surface Elasticity ◽  
Air Bubbles ◽  
Huge Impact ◽  
The Stability ◽  
Air Liquid Interface

In order to improve the stability of air bubbles in fresh concrete, it is of great significance to have a better understanding of the mechanisms and main influencing factors of bubble stability. In the present review, the formation and collapse process of air bubbles in fresh concrete are essentially detailed; and the advances of major influencing factors of bubble stability are summarized. The results show that the surface tension of air–liquid interface exerts a huge impact on bubble stability by reducing surface free energy and Plateau drainage, as well as increasing the Gibbs surface elasticity. However, surface tension may not be the only determinant of bubble stability. Both the strength of bubble film and the diffusion rate of air through the membrane may also dominate bubble stability. The application of nano-silica is a current trend and plays a key role in ameliorating bubble stability. The foam stability could be increased by 6 times when the mass fraction of nano-particle reached 1.5%.

scholarly journals Preparation of foaming agents for dust suppression of coal particles

2019 ◽  
pp. 12-18
Author(s):  
Zh.B. Ospanova ◽  
S. Toktagul ◽  
A. Tasmagambetova ◽  
M. Asadov
Keyword(s):  
Surface Tension ◽  
Anionic Surfactants ◽  
Foam Stability ◽  
Sodium Dodecyl ◽  
Solid Particles ◽  
Foaming Agents ◽  
Coal Particles ◽  
Foaming Capacity ◽  
The Stability ◽  
Surface Tension Isotherms

The results of the study of foams stabilized by solid coal particles are given. The method of sedimentation analysis determined the most likely radius of coal particles equal to 20.28 microns. Foaming ability was determined by the height of the foam column obtained by the method of bubbling within 1 min. Foam stability was determined by the time of complete destruction of the foam column. Foams stabilized by the compositions of anionic surfactants – sodium dodecyl sulfate (DDSNa) and sulfonol (SF) with polyvinyl alcohol (PVA) in the presence of hydrophobic solid particles of coal showed greater foaming capacity and stability compared to foams from individual surfactants. The surface tension isotherms of aqueous solutions of surfactants, PVA, and their mixtures were obtained. An increase in the stability of foams in the presence of coal particles corresponds to a decrease in the surface tension at the liquid-gas interface. The stability of foams obtained from surfactant-PVA compositions is explained by the combined influence of thermodynamic (reduction of surface tension) and structural-mechanical (increase in viscosity of inter-membrane fluid) of stability factors. These properties of foams can be used to suppress dust in coal mining.

Quality Evaluation of Air Entraining Agent Based on Air Void Parameters of Fresh Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 593-599
Author(s):  
Lu Yang ◽  
Yong Jiang Xie ◽  
Hua Jian Li
Keyword(s):  
Surface Tension ◽  
Frost Resistance ◽  
Fresh Concrete ◽  
Diameter Distribution ◽  
Hardened Concrete ◽  
Air Bubbles ◽  
Spacing Factor ◽  
Durability Index ◽  
Air Void

In order to evaluate the quality of air entraining agent quickly and effectively. Air void parameters of fresh concrete with different air entraining agents were studied by Air Void Analyzer (AVA). The spacing factor and durability index of hardened concrete were tested and the relationship between the surface tension of air entraining agent and frost resistance of concrete was compared. The results showed that, the quality of air entraining agent can be evaluated quickly and effectively by diameter distribution of air bubbles in fresh concrete and spacing factor of fresh concrete. AEA2 introduced much more big air bubbles into concrete which is bad for the frost resistance of concrete. The quality of AEA2 was the worst, so the durability index of hardened concrete was 58.7%. Quality of air entraining agent cannot be characterized by properties of air entraining agent, but air entraining ability can be characterized by surface tension of air entraining agent. Keywords: air entraining agent (AEA), air void parameter, fresh concrete

Polidocanol foam stability in terms of its association with glycerin

2013 ◽  
Vol 29 (5) ◽  
pp. 304-309 ◽  
Author(s):  
R Rial ◽  
L S Hervas ◽  
G Monux ◽  
A Galindo ◽  
A Martin ◽  
...  
Keyword(s):  
Surface Tension ◽  
Foam Stability ◽  
Control Group ◽  
Foam Sclerotherapy ◽  
Time Control ◽  
Group 3 ◽  
Group 2 ◽  
The Stability ◽  
Microscopic Measurement ◽  
Group 1

Objectives: Foam sclerotherapy effectiveness mainly depends on the concentration of the sclerosing agent and foam stability. The objective of this study was to determine if the addition of glycerol at different concentrations contributes to the stability of polidocanol foam. Materials and methods: Control Group: 3% polidocanol. Group 1: polidocanol 3% + glycerin 1.66%. Group 2: polidocanol 3% + glycerin 3.3%. Group 3: polidocanol 3% + Glycerin 5%. Tessari standard method. Five recordings were made for each mixture. Early visual liquefaction time and half liquid time decay were recorded in seconds. Microscopic measurement of the foams. Mixtures surface tension measurement (N/m). Results: Early visual liquefaction: Control Group: 27 (± 3.11); Group 1: 67.8 (± 6.49); Group 2:48.6 (± 8.2); and Group 3: 35.8 (± 4.49). Half-liquid time: Control: 129.2 (± 11.00); Group 1: 260.4 (±18.99); Group 2: 224.6 (±13.03); and Group 3: 189.2 (±8.52). Bubbles/mm2–diameter–wall thickness: Control: 68–98 μm-7 μm; Group 1: 189–60 μm-9 μm; Group 2: 76–92 μm-12 μm; and Group 3: 49–112 μm-20 μm. Surface tension: Control = 5.54 N/m; Group 1 = 5.45 N/m; Group 2 = 5.35 N/m; and Group 3 = 5.21 N/m. Conclusions: Small amounts of glycerin highly increase the stability and quality of polidocanol foam. This simple chemical method is easily reproducible and applicable.

The Role of Surface Transport in the Stability and Breakdown of Foams

1952 ◽  
Vol 5 (4) ◽  
pp. 697 ◽  
Author(s):  
WE Ewers ◽  
KL Sutherland
Keyword(s):  
Surface Tension ◽  
Foam Stability ◽  
Surface Film ◽  
High Surface ◽  
Active Material ◽  
Dominant Factor ◽  
Surface Transport ◽  
The Stability ◽  
Surface Active Material

A new theory of foam stability is proposed which demonstrates that the transport of substrate. accompanying a movement of the surface of the bubble film, is a dominant factor in the stability of foams and in the action of foam breakers. The surface moves from a region of low surface tension (high surface pressure) to a region of high surface tension. The surface tension gradients arise from disturbances which may be caused by mechanical or thermal shocks, or by the addition to the surface of particles, droplets, or vapour of a surface-active material. When the surface tension is highest at the centre of disturbance the film mill be stable ; when the surface tension is lowest at this point the surface film and hence the substrate will be moved away from this point and the film will rupture.

scholarly journals A pH-Responsive Foam Formulated with PAA/Gemini 12-2-12 Complexes

2021 ◽  
Vol 5 (3) ◽  
pp. 37
Author(s):  
Hernán Martinelli ◽  
Claudia Domínguez ◽  
Marcos Fernández Leyes ◽  
Sergio Moya ◽  
Hernán Ritacco
Keyword(s):  
Surface Tension ◽  
Dynamic Surface Tension ◽  
Foam Formation ◽  
Ph Responsive ◽  
Dynamic Surface ◽  
X Ray ◽  
Equilibrium Surface Tension ◽  
Potential Applications ◽  
The Stability ◽  
Air Interfaces

In the search for responsive complexes with potential applications in the formulation of smart dispersed systems such as foams, we hypothesized that a pH-responsive system could be formulated with polyacrylic acid (PAA) mixed with a cationic surfactant, Gemini 12-2-12 (G12). We studied PAA-G12 complexes at liquid–air interfaces by equilibrium and dynamic surface tension, surface rheology, and X-ray reflectometry (XRR). We found that complexes adsorb at the interfaces synergistically, lowering the equilibrium surface tension at surfactant concentrations well below the critical micelle concentration (cmc) of the surfactant. We studied the stability of foams formulated with the complexes as a function of pH. The foams respond reversibly to pH changes: at pH 3.5, they are very stable; at pH > 6, the complexes do not form foams at all. The data presented here demonstrate that foam formation and its pH responsiveness are due to interfacial dynamics.

Electrohydrodynamic stability: Taylor–Melcher theory for a liquid bridge suspended in a dielectric gas

2002 ◽  
Vol 452 ◽  
pp. 163-187 ◽  
Author(s):  
C. L. BURCHAM ◽  
D. A. SAVILLE
Keyword(s):  
Surface Tension ◽  
Dielectric Constant ◽  
Electric Fields ◽  
Liquid Bridge ◽  
Numerical Solutions ◽  
Specific Conductivity ◽  
Axisymmetric Deformation ◽  
Aspect Ratios ◽  
The Stability ◽  
Theory And Experiment

A liquid bridge is a column of liquid, pinned at each end. Here we analyse the stability of a bridge pinned between planar electrodes held at different potentials and surrounded by a non-conducting, dielectric gas. In the absence of electric fields, surface tension destabilizes bridges with aspect ratios (length/diameter) greater than π. Here we describe how electrical forces counteract surface tension, using a linearized model. When the liquid is treated as an Ohmic conductor, the specific conductivity level is irrelevant and only the dielectric properties of the bridge and the surrounding gas are involved. Fourier series and a biharmonic, biorthogonal set of Papkovich–Fadle functions are used to formulate an eigenvalue problem. Numerical solutions disclose that the most unstable axisymmetric deformation is antisymmetric with respect to the bridge’s midplane. It is shown that whilst a bridge whose length exceeds its circumference may be unstable, a sufficiently strong axial field provides stability if the dielectric constant of the bridge exceeds that of the surrounding fluid. Conversely, a field destabilizes a bridge whose dielectric constant is lower than that of its surroundings, even when its aspect ratio is less than π. Bridge behaviour is sensitive to the presence of conduction along the surface and much higher fields are required for stability when surface transport is present. The theoretical results are compared with experimental work (Burcham & Saville 2000) that demonstrated how a field stabilizes an otherwise unstable configuration. According to the experiments, the bridge undergoes two asymmetric transitions (cylinder-to-amphora and pinch-off) as the field is reduced. Agreement between theory and experiment for the field strength at the pinch-off transition is excellent, but less so for the change from cylinder to amphora. Using surface conductivity as an adjustable parameter brings theory and experiment into agreement.

THE STABILITY ANALYSIS OF HEAT TRANSFER IN SATURATED LIQUID FILM OF THE SPECIAL MATERIALS

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1547-1550
Author(s):  
YOULIANG CHENG ◽  
XIN LI ◽  
ZHONGYAO FAN ◽  
BOFEN YING
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Surface Tension ◽  
Stability Analysis ◽  
Liquid Film ◽  
Nonlinear Relationship ◽  
Saturated Liquid ◽  
Nonlinear Surface ◽  
Isothermal Wall ◽  
The Stability

Representing surface tension by nonlinear relationship on temperature, the boundary value problem of linear stability differential equation on small perturbation is derived. Under the condition of the isothermal wall the effects of nonlinear surface tension on stability of heat transfer in saturated liquid film of different liquid low boiling point gases are investigated as wall temperature is varied.

Tracing surfactant transformation from cellular release to insertion into an air-liquid interface

2004 ◽  
Vol 286 (5) ◽  
pp. L1009-L1015 ◽  
Author(s):  
T. Haller ◽  
P. Dietl ◽  
H. Stockner ◽  
M. Frick ◽  
N. Mair ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cultured Cells ◽  
High Surface ◽  
Lamellar Body ◽  
Liquid Interface ◽  
Alveolar Type ◽  
Tensile Forces ◽  
Modify Surface ◽  
Fluorescence Imaging Microscopy ◽  
Air Liquid Interface

Pulmonary surfactant is secreted by alveolar type II cells as lipid-rich, densely packed lamellar body-like particles (LBPs). The particulate nature of released LBPs might be the result of structural and/or thermodynamic forces. Thus mechanisms must exist that promote their transformation into functional units. To further define these mechanisms, we developed methods to follow LBPs from their release by cultured cells to insertion in an air-liquid interface. When released, LBPs underwent structural transformation, but did not disperse, and typically preserved a spherical appearance for days. Nevertheless, they were able to modify surface tension and exhibited high surface activity when measured with a capillary surfactometer. When LBPs inserted in an air-liquid interface were analyzed by fluorescence imaging microscopy, they showed remarkable structural transformations. These events were instantaneous but came to a halt when the interface was already occupied by previously transformed material or when surface tension was already low. These results suggest that the driving force for LBP transformation is determined by cohesive and tensile forces acting on these particles. They further suggest that transformation of LBPs is a self-regulated interfacial process that most likely does not require structural intermediates or enzymatic activation.

The Stability of Potassium Ferrate in Water

2014 ◽  
Vol 881-883 ◽  
pp. 215-218
Author(s):  
Kai Luo ◽  
Gang Cao ◽  
Ming Yu Li ◽  
Gang Ren
Keyword(s):  
Influencing Factors ◽  
Potassium Ferrate ◽  
The Stability

The influencing factors of the stability for the potassium ferrate (K2FeO4), including pH, alkalinity, O3, KI, KClO3, KCl, NaClO3and Na2SiO3, were studied in this work. The results showed that the K2FeO4stability in water is best at about pH=10. The higher the alkalinity is, the stronger of K2FeO4stability would be. The O3had no effect to improve the K2FeO4stability. The K2FeO4stability would be best in water with 15mmol/L NaClO3, 10mmol/L Na2SiO3and 9mol/L alkalinity. Under this condition, the K2FeO4content would be 83.28% after 24h.

A model for mechanical structure of the alveolar duct

1982 ◽  
Vol 52 (4) ◽  
pp. 1064-1070 ◽  
Author(s):  
T. A. Wilson ◽  
H. Bachofen
Keyword(s):  
Surface Tension ◽  
Lung Volume ◽  
Published Data ◽  
Scanning Electron Micrographs ◽  
Fiber System ◽  
Lung Capacity ◽  
Alveolar Duct ◽  
Tissue System ◽  
Line Elements ◽  
Air Liquid Interface

The appearance of the microstructure of the lung as revealed in transmission and scanning electron micrographs of perfusion-fixed air- and saline-filled lungs suggests the following model for the structure of the alveolar duct. There are two networks of force-bearing elements. The first is an interdependent part of the peripheral connective tissue system that starts from the pleura and extends into the interlobar and interlobular fissures. At the sublobular level, its geometry is not yet fully clear. This network is extended by changes in lung volume and is insensitive to surface tension. The second network is composed of the line elements that form the rims of the alveolar openings. This network is the terminal part of the axial fiber system that surrounds bronchi, bronchioli, and arteries. The line elements of this network are extended by the outward force of surface tension. The two-dimensional alveolar walls that form the alveoli are negligible mechanical components except as platforms for surface tension at the air-liquid interface. An analysis of the mechanics of this model yields relations among surface area, recoil pressure, lung volume, and surface tension that are consistent with published data for lung volumes below 80% of total lung capacity.

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