Effect of solid material and surfactant presence on interactions of bubbles with horizontal solid surface (original) (raw)
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BUBBLE COLLISIONS WITH HYDROPHOBIC AND HYDROPHILIC SURFACES IN a-TERPINEOL SOLUTIONS
2003
Influence of α-terpineol on phenomena occurring when a gas bubble approaches (collides with) hydrophilic (glass) and hydrophobic (Teflon) solid surfaces was revealed using high-speed camera (1182 frames/s). It was found that the bubble approaching the solid surface bounced backwards from the surface and its shape pulsated rapidly with frequency over 1000Hz. Number of the bouncing cycles and magnitude of the shape pulsations were decreasing with increasing α-terpineol concentrations. In distilled water the amplitude, frequency and number of the "approach-bouncing" cycles were identical at Teflon and glass interface. In of α-terpineol solutions a "necking" formation was recorded at Teflon surface, but not at the glass. The "necking" formation is a straightforward indication that the threephase contact was formed. We found the most intriguing that a small amount of α-terpineol (adsorption coverage of 0.6%) sped-up and affected in such significant degree the bubble attachment to the hydrophobic surface. It was found that the induction time of the bubble attachment to Teflon was 5 milliseconds in α-terpineol presence. The average thickness of the thin liquid film separating the bubble and Teflon was estimated to be ca. 2,7 µm at the film rupture.
Physicochemical characterization of glass and polyethylene surfaces treated with different surfactants and their effects on bacterial adhesion, 2021
Bacterial proliferation in the form of biofilm fixed on a substrate is the result of a set of physical, chemical and biological processes. Microbial adhesion to a substrate is often considered to be the result of physicochemical interactions between the substrate and the microbial cells. These interactions include electrostatic interactions, Van der Waals interactions and acid-base interactions (electron donor-electron acceptor). The exact role of these physicochemical properties is still poorly documented. The purpose of this work is to provide some clarifications on this subject. The phenomenon of adhesion is often studied on clean surfaces, whereas in reality, it is always conditioned depending on its environment (medical, food or cosmetic). This is why in the present work we treated two different surfaces: glass and polyethylene, with diverse surfactants: nonionic, anionic and cationic. The choice of surfactants was motivated by its wide application in different fields. The physicochemical properties of the two substrata (treated and untreated) were defined using contact angle measurements. Moreover, the adhesive behavior of Staphylococcus aureus, as a bacterial model, on the studied substratum was assessed. The obtained results indicate that the physicochemical parameters of the two supports have changed in a specific way to each surfactant. The non-ionic surfactant turned both the surfaces more hydrophilic. However, the anionic and cationic surfactants have reversed the physicochemical characteristics of the surfaces. The correlation coefficients of the physicochemical properties and the adhesive behavior show that there is an association between the wettability of the two surfaces and the rate of the adherent cells.
Effect of Swelling of a Polymer Surface on Advancing and Receding Contact Angles
Journal of Colloid and Interface Science, 1996
alkanes between the monolayer molecules; this is not possi-The kinetics of modification of a fluoropolymer coating (FC ble for the longer alkanes whose dimensions exceed the cross 722, 3M Company) during its contact with octane, dodecane, and section of the monolayer cavities (3). The penetration of hexadecane is studied via measurement of quasi-static (velocity the liquid into the polymer surface might loosen the polymer independent) advancing and receding dynamic contact angles. A chains and cause surface swelling. As noted by Adam (4) decrease in both angles with the time of contact between solid and this process also results in a decrease of the static contact liquid is observed and it is interpreted as the result of swelling of angle. Such a decrease of the advancing contact angles of the polymer. By means of a theoretical extrapolation of the u R (t) CH 2 I 2 , a-bromonaphthalene, and aniline on crosslinked data to t Å 0, based on an equation relating u R (t) to swelling polystyrene was observed by Good and Kotsidas (5). kinetics, the experimentally inaccessible receding contact angle on dry coating, u 0 R , is determined. The contact angle hysteresis on
The influence of flotation agent concentration on the wettability and flotability of polystyrene
Journal of Colloid and Interface Science, 2005
The fundamental flotation process is the formation of a flocculant by air bubbles and solid particles in an aqueous solution. The behavior of plastic particles is significantly influenced by the wettability of the plastics. In this article the reciprocal relationship between the flotability and wettability of polystyrene was studied at different concentrations of flotation agents, particularly terpineol, polyethylene glycol dodecyl ether, tannic acid, and calcium lignosulfonate. The conclusions obtained demonstrate the dissimilar action of flotation depressants, what means different adhesion mechanisms on a plastic surface. 2005 Elsevier Inc. All rights reserved.
Theory of Adhesion and its Practical Implications A Critical Review
The quality and durability of a coating is directly related to the nature of adhesion. Chemists tend to associate adhesion with the energy liberated when two surfaces meet to form an intimate contact termed as an interface. In other words, adhesion may be defined as the energy required to dismantle the interface between two materials. Physicists and Engineers usually describe adhesion in terms of forces, with the force of adhesion being the maximum force exerted when two adhered materials are separated. There are many theories regarding the mechanism of adhesion such as adsorption (van der Waals forces), electrostatic, diffusion (entanglement of polymers with a substrate), chemical bonding, mechanical interlocking etc. all of which may play a significant role in interfacial bonding. The energy required to separate the adhesive (coating) and the substrate is a function of the adhesion level i.e. interactions at the interface, but it also depends on the mechanical and viscoclastic properties of the coating materials. It is definite that all the mechanisms mentioned could affect bond strength and adhesion. Because of the complexity of adhesion phenomena, there are many models for it. None of them, on its own, can fully explain adhesion. However, each model describes a part of the complex processes involved in adhesion. For optimum adhesion it is therefore absolutely essential to ensure good wetting by the coating material applied, thus creating ideal conditions for causing the film forming agent molecules to approach the substrate. In general, for good substrate wetting the surface tension of the coating material (p) should be lower than the surface tension of the substrate (s), or they should at least be equal. The real reason for insufficient substrate wetting is the too high surface tension of the liquid coating, however, other factors will also influence how strongly this defect shows up. It can only be performed indirectly by measuring the contact angle of droplets of liquid which have been applied to the solid surface being examined. A measurement of contact angle has been discussed briefly. The range of chemicals used as adhesion promoters includes silanes, silicones, titanium compounds, zirconates, amides, imines, phosphates, and specially modified polymers. Furthermore, there are binders, plasticizers, and additives (e.g., wetting agents) which though intended for other purposes, have the secondary effect of providing good adhesive strength. In terms of adhesive strength, it is in many cases the overall formulation of a paint or other coating material which is decisive. The mode of action of silanes has been briefly reviewed as these are the future commercially viable coupling agents (adhesion promoters) for external coating of pipelines. These coupling agents like epoxy and amino silanes are often applied as very thin layers on substrates such as steel/aluminium before an adhesive is applied. In many cases, only TOFSIMS is able to characterize the very thin layer of the coupling agent on the substrate.
Journal of Colloid and Interface Science, 1994
The contact angle for varying sizes of drops and air bubbles are n.°t fully ~ecognized. Until ~ecentIy, t~e position was that was measured on clean, heterogeneous, and rough solid surfaces. the hn.e tensIon phenomenon IS responsIble for the effect of A linear correlation of the cosine of the contact angle vs recip-dropslZe on ~ntacta~gle (7,9, 10) according to the modified rocal of the drop (bubble) base radius was obtained for the tet-Young equatIon, WhIch was presented in the literature as radecane / water / quartz and air / water / polyethylene systems in follows ( I, 16): which pure single-component liquids and freshly prepared cI;an soli~ surfaces were used. It was found that solid surface imper-'Ysv -'YSL = 'YLV cos 8 + ~ .
Journal of Colloid and Interface Science, 1996
YLY, 'YSY, and 'YSL are the interfacial tensions, the L, S, and was more evident at reduced pressures for the water/copper V subscripts corresponding to liquid, solid, and vapor, re-system (25-27). Also, they demonstrated that the equilibspectively; e is the contact angle; 'YSLY is the line tension: rium film pressure has a negligible effect on the contact the excess free energy in the region of the triple interface angle and the contact angle/drop size relationship for water/ (II). Equation [I] is applicable for homogeneous, rigid, flat, (argon: saturated with water or organic solvent)/PTFE syshoriz?ntal, and smooth solid surfaces. tern (28). Further, it was found that the contact angle/drop UsIng Eq. [I], Vesselovsky and Pertzov (3) calculated size relationship depends on the temperature of the experithe line tension to be from -1.3 X 10-6 to -14 X 10-6 J/ ment (28). When the temperature of the system was 25m. (The negative line tension indicates that the contact angle 75°C the contact angle decreased with decreasing water drop as measured for the aqueous phase increased with increasing volume for a polymer (PTFE) surface as well as for metal bubble size.) Unfortunately, as they correctly discussed (3), surfaces (stainless steel, gold, copper). This correlation the line tension values determined were much larger than changed at the boiling point of water and the contact angle those that would be expected from intermolecular interac-decreased with increasing drop volume in these circumtions.
Bubble collisions with hydrophobic and hydrophilic surfaces in α-terpineol solutions
Influence of α-terpineol on phenomena occurring when a gas bubble approaches (collides with) hydrophilic (glass) and hydrophobic (Teflon) solid surfaces was revealed using high-speed camera (1182 frames/s). It was found that the bubble approaching the solid surface bounced backwards from the surface and its shape pulsated rapidly with frequency over 1000Hz. Number of the bouncing cycles and magnitude of the shape pulsations were decreasing with increasing α-terpineol concentrations. In distilled water the amplitude, frequency and number of the "approach-bouncing" cycles were identical at Teflon and glass interface. In of α-terpineol solutions a "necking" formation was recorded at Teflon surface, but not at the glass. The "necking" formation is a straightforward indication that the three-phase contact was formed. We found the most intriguing that a small amount of α-terpineol (adsorption coverage of 0.6%) sped-up and affected in such significant degree t...