Surface energies table

Some of the most common bulk material properties that influence wear are the melting point, Young s modulus, yield strength, hardness, and surface energy. Table 2.2 provides a summary of these values for selected pure metals. To provide optimal antiwear properties, the material should ... 

The total volume of weakly (C ) and strongly (Cuw) bound waters (unfrozen at T < 273 K) at the silica interfaces (Table 38.5) is markedly larger than Vp (but significantly lower than Vemp) with one exception for SI-6 (Table 1). With increasing specific surface area of the first series samples, there is tendency of reduction of the free surface energy (Table 5, js) and the amount of weakly bound water Besides, the AG Cuw)y... 

The particle size distribution of the capsule systems has a decisive effect on the surface areas, the encapsulated volumes, and the resulting surface energies (Table 60.1). 

The surfaces of many plastics and rubbers have low surface energies (Table 3.1) such that wetting by an adhesive is inhibited unless special surface pretreatment processes have been employed. However, plastics which contain polar groups such as PVC, nylons and acrylics are bondable with a minimum of surface treatment. 

There are three broad types of intermolecular forces of adhesion and cohesion (7) quantum mechanical forces, pure electrostatic forces, and polarization forces. Quantum mechanical forces account for covalent bonding. Pure electrostatic interactions include Coulomb forces between charged ions, permanent dipoles, and quadrupoles. Polarization forces arise from dipole moments induced by the electric fields of nearby charges and other permanent and induced dipoles. Ideally, the forces involved in the interaction at a release interface must be the weakest possible. These are the polarization forces known as London or dispersion forces that arise from interactions of temporary dipoles caused by fluctuations in electron density. They are common to all matter and their energies range from 0.1 to 40 kJ/mol. Solid surfaces with the lowest dispersion-force interactions are those that comprise aliphatic hydrocarbons, and fluorocarbons, and that is why such materials dominate the classification table (Table 1) and the surface energy table (Table 2). 

It should be noted that all reactions described in Section 5.8 change dramatically surface properties, in particular, the surface energy (Table 5.3). The complex glass surfece can finally be schematized as glass bulk/hydrated and depolymer-ized glass/water/pollution. Functionalizing the surfece of glass supposes it is first cleaned up it can also be treated (Chapter 12). 

The uncertainties in choice of potential function and in how to approximate the surface distortion contribution combine to make the calculated surface energies of ionic crystals rather uncertain. Some results are given in Table VII-2, but comparison between the various references cited will yield major discrepancies. Experimental verification is difficult (see Section VII-5). Qualitatively, one expects the surface energy of a solid to be distinctly higher than the surface tension of the liquid and, for example, the value of 212 ergs/cm for (100)... 

The illustrative data presented in Table VII-3 indicate that the total surface energy may amount to a few tenths of a calorie per gram for particles on the order of 1 /xm in size. When the solid interface is destroyed, as by dissolving, the surface energy appears as an extra heat of solution, and with accurate calorimetry it is possible to measure the small difference between the heat of solution of coarse and of finely crystalline material. 

Make the following approximate calculations for the surface energy per square centimeter of solid krypton (nearest-neighbor distance 3.97 A), and compare your results with those of Table VII-1. (a) Make the calculations for (100), (110), and (111) planes, considering only nearest-neighbor interactions, (b) Make the calculation for (100) planes, considering all interactions within a radius defined by the sum... 

Table 7.2 Calculated surface energies of ceramic oxides...

Priming to improve adhesion Table 7 Surface energies of polymeric and metal oxide surfaces 459... 

The specialty class of polyols includes poly(butadiene) and polycarbonate polyols. The poly(butadiene) polyols most commonly used in urethane adhesives have functionalities from 1.8 to 2.3 and contain the three isomers (x, y and z) shown in Table 2. Newer variants of poly(butadiene) polyols include a 90% 1,2 product, as well as hydrogenated versions, which produce a saturated hydrocarbon chain [28]. Poly(butadiene) polyols have an all-hydrocarbon backbone, producing a relatively low surface energy material, outstanding moisture resistance, and low vapor transmission values. Aromatic polycarbonate polyols are solids at room temperature. Aliphatic polycarbonate polyols are viscous liquids and are used to obtain adhesion to polar substrates, yet these polyols have better hydrolysis properties than do most polyesters. 

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