Physical adhesion

Tire cords are characterized for their physical, adhesion, and fatigue properties for use in tires. These characterizations are conducted under normal and varying test conditions to predict their performance during tire operation. Various test methods used to characterize tire cords are described. 

Selected experiments from Fig. 3 were repeated, but in the presence of such Teflon shavings. Yield data were comparable. Importantly, the recovered catalyst residues became more compact and firmer, despite the added mass of the Teflon , suggestive of genuine physical adhesion or attraction. The catalyst residues were easier to manipulate, and less leaching occurred. 

Plasma films are usually highly cross-linked, resistant to higher temperatures, resistant to abrasion and chemical attack, and are highly adherent to the surface. Adhesion to the surface is generally high both because the growing polymer complex can fit the surface contour and thus lock-itself in (physical adhesion), and because in many instances, the species are active enough to chemically react with the surface molecules to chemically bond to the surface. The surface can be prepared so that the chemical reaction is enhanced. 

It is clear from the above considerations that for D R van der Waal s interaction energy (so-called physical adhesion strength) between larger particles and the surface decays much more slowly with distance than that between a molecule and the surface. On the other hand, at large separations, i.e., D R, the interaction decays very quickly with distance. Also note that the... 

Physical adhesion This mechanism is controlled by diffusive bonding, where the diffusivity increases with increasing contact temperature according to Fields law. This can be maximised by substrate preheating. Because of the small diffusion depth (produced by the rapid solidification), the diffusive adhesion generally plays only a minor role as an adhesion mechanism. 

Adsorption is the physical adhesion of molecules or colloids to the surfaces of solids, without chemical reaction. 

Polymer foils and sheets possess unique properties including a high aspect ratio, a great flexibility and physical adhesion to ubiquitous surfaces [125]. When such films are produced from biodegradable or blocompatlble materials, they can serve as coating material for biomedical Implants. 

Polymer films have unique properties including high aspect ratio, high flexibility, physical adhesion to ubiquitous surfaces, and attractive structural colors. The films can be formed from biodegradable and biocompatible polymer... 

Fitzer and co-workers [103] showed that the concentration of reactive fiber surface groups on HM fiber is about one magnitude less than for HT fiber, whilst wetting measurements and nitrogen determinations showed that the adhesion between fiber and matrix is at least 50% chemical in nature. The BET surface area of oxidized HT fiber was about forty times that of HM fiber, suggesting that physical adhesion or mechanical interlocking was not a contributory factor. 

Adhesion, by its definition, depends on the ability of two unlike phases to hold themselves together across a common interface. Physical adhesion must first take place before any other bonding processes such as chemical reaction can occur, and such physical adhesion depends on the strength of intermolecular force interaction, on the area of contact and on the distance separating the atoms forming the top layer of each surface (see Dispersion forces, polar forces). When both phases are undeformable, such as with two solids that are not atomically smooth, poor adhesion results because an insufficient area of each surface is in atomic contact with the other. When one phase is deformable, such as with a liquid of low viscosity, physical adhesion takes place at all parts of the surface. Physical adhesion with a liquid in contact with a solid leads to spreading and wetting processes that now depend on the competition of adhesion forces with cohesion forces within the liquid. 

Most stains consist of colored substances of natural origin belonging to the polyphenol, carotenoid, or chlorophyll class. Artificial food colorants, cosmetic ingredients, and decorative dyes complete the stain portfolio. Very often stains are complex mixtures of spilled food preparations or beverages. Combined with oils, fats, or other organic material, such as proteins, starch, or waxes, the properties of stains are quite different from those of isolated dyes. Only a small proportion of all stains is fixed on surfaces by physical adhesion. On fibers, in particular, strong interactions often result in covalent bond formation. This process is more important on cotton than on synthetic fabrics. 

The three possible routes for silica aerogel binder composites fabrication discussed thus far offer a combination of physical adhesion and covalent bonding... 

When the adsorption results not only from electrostatic, but (additionally) from physical adhesion (e.g. van-der Waals forces, hydrogen bonding) and/or chemical bonds (covalent or ionic) too, it is inevitably affected by the ion type (e.g. by mass and electronegativity) and solid phase (e.g. by atomic lattice). Such a specific adsorption can increase the value of the effective surface charge or may lead to a charge reversal. Specifically-adsorbed ions are partially or completely dehydrated and directly associated to the surface. They are, consequently, located at the IHP (cf. Fig. 3.3). 

Physical methods are reversible reformations, in the form of physical adhesion between two polymers. Physical adhesion, or immerse precipitation, does not change the interface. Therefore, the two polymers can easily be disunited using selective solvents. Adhering cell protein as the biomimetic substance and coating a substrate in a melting process are some examples of physical modification. However, homogeneous thickness of the conductive polymer cannot be achieved with these methods, resulting in various conductivities in different locations of the polymer. 

Figure 6.6 Adhesion theories (a) physical adhesion at the interface (b) specific interactions (chemisorption) (c) diffusion mechanism (d) physical interlocking. Reprinted from Myers (1999), with permission from John Wiley Sons, Ltd...

---