Interfacial tension adhesion

Contact angles and inteifacial tension D E PACKHAM Young s equation work of adhesion, interfacial tension and surface energy... 

Surface Tension. Interfacial surface tension between fluid and filter media is considered to play a role in the adhesion of blood cells to synthetic fibers. Interfacial tension is a result of the interaction between the surface tension of the fluid and the filter media. Direct experimental evidence has shown that varying this interfacial tension influences the adhesion of blood cells to biomaterials. The viscosity of the blood product is important in the shear forces of the fluid to the attached cells viscosity of a red cell concentrate is at least 500 times that of a platelet concentrate. This has a considerable effect on the shear and flow rates through the filter. The surface stickiness plays a role in the critical shear force for detachment of adhered blood cells. 

The quantity of energy required to separate the two Hquids increases as the interfacial tension between them decreases the lower the interfacial energy, the stronger the adhesion. 

However, the surface tension of the soHd, y, and the soHd—Hquid interfacial tension, y, caimot be measured direcdy by simple means. The work of adhesion of the soHd to the Hquid usually deterrnined by other techniques. 

The use of the harmonic mean often leads to better predictions of interfacial tensions between polymers and better contact angles between liquids and polymer solids, but the criterion for maximization of the work of adhesion is the same as... 

With respect to good adhesion, reduced interfacial tension, fine distribution of TLCP phase, and the use of a compatibilizer can be very effective for this purpose. Remarkably improved mechanical properties (good impact properties as well as tensile properties) can be obtained with optimum amounts of the compatibilizer. Excess amounts of the compatibilizer causes the emulsifying effect to coalesce the dispersed TLCP... 

Morphological studies of these blends revealed that the compatibilization was very effective in decreasing the interfacial tension and increasing the adhesion between the two phases (Fig. 9). 

In a fundamental sense, the miscibility, adhesion, interfacial energies, and morphology developed are all thermodynamically interrelated in a complex way to the interaction forces between the polymers. Miscibility of a polymer blend containing two polymers depends on the mutual solubility of the polymeric components. The blend is termed compatible when the solubility parameter of the two components are close to each other and show a single-phase transition temperature. However, most polymer pairs tend to be immiscible due to differences in their viscoelastic properties, surface-tensions, and intermolecular interactions. According to the terminology, the polymer pairs are incompatible and show separate glass transitions. For many purposes, miscibility in polymer blends is neither required nor de-... 

This block copolymer acts as an emulsifying agent in the blends leading to a reduction in interfacial tension and improved adhesion. At concentrations higher than the critical value, the copolymer forms micelles in the continuous phase and thereby increases the domain size of the dispersed phase. 

The better interaction observed with the unmodifled clay was also explained in terms of surface energy. The values of surface energy of the fluoroelastomer and the clays, along with work of adhesion, spreading coefficient and interfacial tension are reported in Table 2.4. 

The force needed to break the mineral-air interface is called the work of adhesion, WA, and is equal to the work needed to separate the mineral-air interface and produce in place air-water and mineral-water interfaces. This, in other words, may be represented with interfacial tensions in place as ... 

Figure 4c shows that the amount of adsorbed proteins is rapidly saturated within several minutes of exposing serum-containing medium to a surface. Albumin, the most abundant serum protein, was expected to preferentially adsorb onto the surfaces during early time points. Then, adsorbed albumin was expected to be displaced by cell adhesion proteins. To investigate the effect of preadsorbed albumin displacement on cell adhesion, SAMs were first exposed to albumin then, HUVECs suspended in a serum-supplemented medium were added [21, 42]. Very few cells adhered to hydrophobic SAMs that had been pretreated with albumin, due to the large interfacial tension between water and the hydrophobic surfactant-like surface. Albumin was infrequently displaced by the cell adhesive proteins Fn and Vn. One the other hand, HUVECs adhered well to hydrophilic SAM surfaces that had been preadsorbed with albumin. In that case, the preadsorbed albumin was readily displaced by cell adhesive proteins. 

In a similar manner, an expression for the interfacial tension, Yf can be written using the geometric mean definition for work of adhesion, Wa (see Figure 8), and the Girifalco-Good interaction parameter (17-18), as. 

Freitas, A. A., Quina, F.H., and Carroll, F.A. Eshmahon of water-organic interfacial tensions. A linear free energy relationship analysis of interfacial adhesion, J. Phys. Chem. B, 101 (38) 7488-7493, 1997. 

The direct determination of matrix/filler interaction is difficult, indirect techniques are used in most cases. These employ the principles discussed in Sect. 3.2. The surface tension of the components and interfacial tension or ac-id/base interaction parameters must be known in order to determine the reversible work of adhesion. Adsorption-desorption techniques, which use small molecular weight materials having an analogous structure to the polymer, can be used for the estimation of interfacial interaction. 

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