Adhesive behavior

Wear. Ceramics generally exhibit excellent wear properties. Wear is deterrnined by a ceramic s friction and adhesion behavior, and occurs by two mechanisms adhesive wear and abrasive wear (43). Adhesive wear occurs when interfacial adhesion produces a localized Kj when the body on one side of the interface is moved relative to the other. If the strength of either of the materials is lower than the interfacial shear strength, fracture occurs. Lubricants (see Lubricants and lubrication) minimize adhesion between adj acent surfaces by providing an interlayer that shears easily. Abrasive wear occurs when one material is softer than the other. Particles originating in the harder material are introduced into the interface between the two materials and plow into and remove material from the softer material (52). Hard particles from extrinsic sources can also cause abrasive wear, and wear may occur in both of the materials depending on the hardness of the particle. 

Viscoelastic polymers essentially dominate the multi-billion dollar adhesives market, therefore an understanding of their adhesion behavior is very important. Adhesion of these materials involves quite a few chemical and physical phenomena. As with elastic materials, the chemical interactions and affinities in the interface provide the fundamental link for transmission of stress between the contacting bodies. This intrinsic resistance to detachment is usually augmented several folds by dissipation processes available to the viscoelastic media. The dissipation processes can have either a thermodynamic origin such as recoiling of the stretched polymeric chains upon detachment, or a dynamic and rate-sensitive nature as in chain pull-out, chain disentanglement and deformation-related rheological losses in the bulk of materials and in the vicinity of interface. 

We assembled a TIRFM with low magnification to study cell adhesion behavior on SAMs with various functional groups [42]. Figure lb shows a schematic illustration of the cell adhesion process and the corresponding TIRFM images. A suspension of cells with fluorescently labeled cell membranes is applied onto a substrate (Fig. lb-1). At first, no bright spots were observed by TIRFM,... 

Fig. 2 TIRFM images of HUVEC adhesion behavior on SAMs with four different types of surface functional groups at the indicated times after first applying the cell suspension. Scale bar 200 pm [42]...

We examined protein adsorption to SAMs that carried four different functional groups [42] and mixed SAMs with different wettabilities [21], Large amounts of serum proteins adsorbed to all these SAMs, but the different surface functional groups greatly affected cell adhesion behavior (Figs. 2 and 3). Thus, the amount of adsorbed proteins did not correlate with the degree of cell adhesion to SAMs. 

Yeast flocculation mechanism can be described as a phenomenon of adhesion to certain surfaces. The ability to adhere to surfaces and to form biofilm is the basis of the pathogenicity of Candida species. Pathogens adhere to mucous membranes and wounds, they stick to medical instruments and prosthesis, and thus contaminate surfaces in food processing facilities. The high mortality rate in disseminated fungal infections caused an increase in the amount of research on the molecular basis of the adhesive phenomena in Candida. This research discovered a considerable overlap in the molecular regulation of all forms of adhesive behavior. ... 

Li JX, Wang J, Shen LR et al (2007) The influence of polyethylene terephthalate surfaces modified by silver ion implantation on bacterial adhesion behavior. Surf Coat Technol 201 8155-8159... 

F-BDAF Tg for various blend compositions, see Fig. 14. The microphase-separated morphology further manifests itself in the self-adhesion behavior of polyimide films derived from such mixtures. For mixture containing at least 25 wt% of the flexible component, peel tests of polyimide bilayer samples prepared by solution casting, bulk failure of the test specimens was observed. Since the flexible component contained fluorine, the samples could be examined by X-ray photoelectron spectroscopy to determine the surface composition. At only 10% loading, the flexible component comprised 100% of the top 75 A of the sample. The surface segregation of the flexible component is believed to be responsible for the adhesion improvements. 

Halogenated butyl rubbers have particularly advantageous adhesion behavior, flexural strength, service life and impermeability to air and water (40). The specific structure of the halogenated butyl rubber depends on the conditions of halogenation. 

Yoon TH, Arnold-McKenna CA, McGrath JE (1992) Adhesion behavior of thermoplastic polyimides and poly(imide siloxane) segmented copolymers influence of test temperatures J Adhes 39(100) 15... 

Yoon TH, McGrath JE (1991) Effect of surface preparation and thermoplastic ahesive structure on the adhesion behavior of peek-graphite composites. Mater Res Soc Symp Proc 190 (Plasma Process Synth Mater) 3 137-142... 

Table 4. Properties of micro-organisms relevant for their adhesion behavior.

Schneberger, G. L., Polymer Structure and Adhesive Behavior, in Adhesives in Manufacturing. 

Schneberger, G. L., Polymer Structure and Adhesive Behavior, in Adhesives in Manufacturing, G. L. Schneberger, ed., Marcel Dekker, New York, 1983. 

There are several analytical tools that provide methods of extrapolating test data. One of these tools is the Williams, Landel, Ferry (WLF) transformation.14 This method uses the principle that the work expended in deforming a flexible adhesive is a major component of the overall practical work of adhesion. The materials used as flexible adhesives are usually viscoelastic polymers. As such, the force of separation is highly dependent on their viscoelastic nature and is, therefore, rate- and temperature-dependent. Test data, taken as a function of rate and temperature, can be expressed in the form of master curves obtained by WLF transformation. This offers the possibility of studying adhesive behavior over a sufficient range of temperatures and rates for most practical applications. Fligh rates of strain may be simulated by testing at lower rates of strain and lower temperatures. 

Three kinds of adhesion tests were used to evaluate the interfacial adhesion behaviors of these systems the results are summarized in Table 32.3. As is evident from the data, excellent water-insensitive adhesion was obtained for all of the plasma interface-engineered IVD/plasma polymer/E-coat systems examined. 

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