Adhesion defined

Adhesiveness, defined as the work necessary to overcome the attractive forces between the surface of the sample and the surface of other materials with which the food comes into contact, e.g. tongue, teeth, palate, etc. (Szczesniak, 1963), is given on the texturometer curve by the negative force area, representing the work needed to pull out the plunger from the sample. This parameter s value may be considered an evaluation of stickiness of jelly. Fracturability, also called brittleness, is given by the measure (%) of the plunger path into the jelly when it breaks. 

Adhesives are used to bond various different substrates such as metal, glass, wood, or plastic among many others (Houwink 1967). The appropriate adhesive and its chemistry have to be chosen in dependence of the application and the substrate which is bonded. A wide range of different chemistries are used to formulate adhesives. The chemical nature of the adhesive defines its field of application. Most adhesives which are used in the industry today are using epoxy-, polyurethane-, acrylic-, and silicone- or rubber chemistry. 

This distinction between 7 s and 7svo seems first to have been made by Bang-ham and Razouk [33] it was also stressed by Harkins and Livingstone [34]. Another quantity, introduced by Bartell and co-workers [35] is the adhesion tension A, which will be defined here as... 

Ideal adhesion simply means the adhesion expected under one or another model situation of uniform materials having intimate contact over a well-defined area. In these cases, the important quantity is the work of adhesion wab between two phases, which is given by... 

Cross G, Schirmeisen A, Stalder A, Grutter P, Tschudy M and Durig U 1998 Adhesion interaction between atomically defined tip and sample Phys. Rev. Lett. 80 4685... 

The abiHty to tailor both head and tail groups of the constituent molecules makes SAMs exceUent systems for a more fundamental understanding of phenomena affected by competing intermolecular, molecular—substrate and molecule—solvent interactions, such as ordering and growth, wetting, adhesion, lubrication, and corrosion. Because SAMs are weU-defined and accessible, they are good model systems for studies of physical chemistry and statistical physics in two dimensions, and the crossover to three dimensions. 

Most of the various strategies which have been proposed to predict relative adhesive interfacial strength are based on thermodynamics. One may define, without ambiguity, as shown in Fig. 3, a thermodynamic work of adhesion , Wa,... 

The most-often cited theoretical underpinning for a relationship between practical adhesion energy and the work of adhesion is the generalized fracture mechanics theory of Gent and coworkers [23-25] and contributed to by Andrews and Kinloch [26-29]. This defines a linear relationship between the mechanical work of separation, kj, , and the thermodynamic work of adhesion ... 

In the adsorption mechanism, adhesion is modeled as occurring across a well-defined interface by molecular interaction across that interface, and is often... 

Visually, failure was mostly eohesive within the adhesive (see Figs. 34 and 46). However, there was a small area of apparent interfacial failure ( initiation zone ) located at one end of each substrate. Line scans were eondueted aeross the initiation zone, from the edge of the substrate to the area of cohesive failure within the adhesive. From the line scans, it was apparent that there were patehes of polymer present in the initiation zone, even when failure appeared to be interfaeial (see Fig. 46). SIMS images of the initiation zone were constructed for various mass numbers (see Figs. 47-49). The images showed well-defined cation-rieh... 

Surface energies are also associated with failure of an adhesive bond, because failure involves forming new surfaces and the appropriate surface energies have to be provided. The surface energy term may be the work of adhesion, VTa, or the work of cohesion, VTcoh. depending on whether the failure is adhesive or cohesive. For phases 1 and 2, these are defined as follows [lOj ... 

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