Adhesion wettability, effect

Adhesives must effectively wet and completely contact the surfaces to assure a strong bond. The ability to wet a surface, wettability, is related to the ease with which a liquid spreads on a solid surface and is essential in maximizing coverage and minimizing voids in the bondlines. Wettability is measured by the equilibrium contact angle, 6, which is defined by balancing surface-tension forces in Young s equation ... 

There are numerous techniques which provide information related to the surface energy of solids. A large array of high-vacuum, destructive and non-destructive techniques is available, and most of them yield information on the atomic and chemical composition of the surface and layers just beneath it. These are reviewed elsewhere [83,84] and are beyond the scope of the present chapter. From the standpoint of their effect on wettability and adhesion, the property of greatest importance appears to be the Lifshitz-van der Waals ( dispersion) surface energy, ys. This may be measured by the simple but elegant technique of... 

The augmentation of the work of adhesion by acid-base effects has, as a consequence, an effect on wettability properties. Identifying /sl in Eq. 26 as W and substituting it into Eq. 3 and Eq. 14, respectively leads to ... 

Thermal aging is another simple pretreatment process that can effectively improve adhesion properties of polymers. Polyethylene becomes wettable and bondable by exposing to a blast of hot ( 500°C) air [47]. Melt-extruded polyethylene gets oxidized and as a result, carbonyl, carboxyl, and hydroperoxide groups are introduced onto the surface [48]. 

After this treatment the surface energy of the fibers is increased to a level much closer to the surface energy of the matrix. Thus, a better wettability and a higher interfacial adhesion are obtained. The polypropylene (PP) chain permits segmental crystallization and cohesive coupling between modified fiber and PP matrix [40]. The graft copolymerization method is effective, but complex. 

The treatment of SBR with fumaric acid solutions avoids the migration of antiadherent moieties to the surface and the treatment with TCI solutions is effective to enhance the adhesion of several mbbers to polyurethane adhesive. Therefore, the combined use of mixtures of TCI and FA solutions should be more effective in improving the adhesion of difficult to bond SBR. The wettability of SBR is improved by treatment with 3 wt% TCI/EA followed by treatment with 0.5 wt% FA/EtOH (3 wt% TCI-0.5 wt% FA), with 0.5 wt% FA/EtOH followed by treatment with 3 wt% TCI/EA (0.5 wt% FA-3 wt% TCI), or with TCI + FA mixtures.However, the extent of the surface modifications produced and the adhesive strength of adhesive joints are mainly due to chlorination with TCI/EA. 

C) Illustration of the effect of work of cohesion of water and work of adhesion to mineral on the mineral wettability. 

Arima Y, Iwata H (2007) Effect of wettability and surface functional groups on protein adsorption and cell adhesion using well-defined mixed self-assembled monolayers. Biomaterials 28 3074-3082... 

Mahlberg, R., Niemi, H.E.M., Denes, F. and Rowell, R.M. (1998). Effect of oxygen and hexameth-yldisiloxane plasma on morphology, wettability and adhesion properties of polypropylene and lignocellulosics. International Journal of Adhesion and Adhesives, 18(4), 283-297. 

Adhesion Tensions and Tar Sand Extraction with Tween Surfactants. Mea-surement of the adhesion tension (t) allows the determination of the wettability of a given solid by a given liquid or surfactant solution. Measurements of adhesion tension between both bitumen or clay surfaces and various surfactant solutions is thus highly relevant to a study of the effects of surfactants in the separation of bitumen from Athabasca tar sand. 

Surface Energetics and Wettability Theory. The surface energetics and wettability theory of adhesion is concerned with the effect of intermolecular and interatomic forces on the surface energies of the adhesive and the adherend and the interfacial energy between the two. 

Wood Extractives. Glue bonds can be affected in many ways by extraneous components on or near the surface of wood. Chen (56) showed that extractive removal did improve bond performance and that the extractives, in part, reduce wettability. This effect is reflected also in Figure 2 from Jordan and Wellons (29). Hergt and Christensen (57) also showed that extractives can slow water adsorption from the adhesive into the wood, thus slowing development of cohesion in the adhesive. 

Increase adhesion tension. Maximize surface tension. Minimize contact angle. Alter surfactant concentration or type to maximize adhesion tension and minimize Marangoni effects. Precoat powder with wettable monolayers, e.g., coatings or steam. Control impurity levels in particle formation. Alter crystal habit in particle formation. Minimize surface roughness in milling. 

It is desirable to find a simple surface property that will induce an equally simple and hence predictable behavior of plasma and its proteins and then of blood and its platelets. Are simple guidelines for building non-thrombogenic materials available or even possible Wettability (96), flow (97, 98y 99,100), and the effects of air/liquid interfaces (101) all seem to be relatively simple, physical factors with a clear effect on platelet adhesion. Physical, hydrophobic bonding, e.g., a force imposed... 

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