Adhesion in vacuum

The substrate 2 is assumed in this case to have 30 and 35 erg cm-2 as y and y, respectively. There is a controversy about expressing the work of adhesion in vacuum by Eq. (6) [13]. y is usually calculated by means of Eq. (6), without any strong theoretical support since there are only few methods available at present for estimating y. Therefore it should be noted that Eq. (10) is a very rough approximation for the work of adhesion in water. In addition, the curve in Fig. 1 was obtained from unsatisfactory experimental results. Nevertheless, it qualitatively represents the features that have been generally observed. In addition, Fig. 2 demonstrates that in both the extreme cases, where the polymer surface is extremely hydrophilic or hydrophobic, W]2,w is quite low but shows a maximum when the polymer surface has a certain hydrophilic-hydrophobic balance. Since the work of adhesion is directly... 

These data indicate that particle adhesion in vacuum is less than in air water vapor increases the adhesive force there are no capillary forces when the particles are under vacuum, while in air these forces are manifested upon the appearance of a liquid bridge in the gap between the contiguous bodies in an atmo-... 

If the surface is dusted in air and then placed under vacuum, the adhesion in vacuum is generally smaller than the corresponding adhesion in air. 

It is well-known that the work of adhesion in vacuum or in air (W ) is defined as... 

A variation on the vibration method is the pulse method, which we used to determine adhesion in vacuum and in the vapor of various liquids (Fig, 11,10),... 

Fig. 3. Definition of thermodynamic work of adhesion, Wa (a) disjoining surfaces in vacuum (b) disjoining surfaces in fluid medium m and (c) disjoining surfaces in presence of vapors from adhesive.

Refractive index is defined as the ratio of the speed of light of a given wavelength in vacuum to the speed of light at the same wavelength in the substance measured. The refractive index of epoxy resins is seldom reported. However, the property is important for cured epoxy adhesives that are used in the assembly of optical devices. 

FIG. 1 Work of adhesion of polymer surface 1 with bovine serum albumin 2 in water (fki2,w) and in vacuum (Wn) as a function of the interfacial free energy between water and polymer 1 (y]w). (From Ref. 1.)... 

Knowledge of interfacial tensions is important in the practical problems of lubrication and adhesion. Successfiil lubrication occurs for a system where a lubricant completely wets a sohd and maintains complete coverage under tribological conditions. The degree of adhesion of a lubricant to a solid or the strength of an adhesive can be determined by the extent to which the free energy of the system is lowered by the adsorption of the lubricant or adhesive. The energy necessary to separate the sohd liquid interface (in vacuum)... 

A very important factor in the utilization of plasma deposition is that both processes are carried out in vacuum. Enhanced adhesion of Parylene C and... 

TABLE 9-1. FRICTION AND ADHESION OF CLEAN COPPER IN VACUUM... 

Once the article is vacuum bagged (Fig. 6.67), it is allowed to cure for a specific amount of time. For articles comprising heat-activated (thermoset) or heat-formed (thermoplastic) resins and adhesives, the vacuum-bagged articles (Fig. 6.68) are cured in ovens or, when more pressure is required, in autoclaves... 

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