Minimally adhesive surfaces

Akhremitchev et al. presented a set-up based on the same principle, namely 1R s-SNOM with a side-illuminated AFM tip, and employed it to characterize nano-structured polymer blends that were used as minimally adhesive surface coatings to prevent biofouHng [57, 58]. Raschke ct al. used sharp Au-coated, forward-pointing ( nose-type ) AFM probes with a radius of 10-15 nm, and obtained fixed-... 

Arce, F.T., Avd, R., Beech, I.B., Cooksey, K.E., and Wigglesworth-Cooksey, B. (2003) Microelastic properties of minimally adhesive surfaces a comparative study of RTVll and Intersleek elastomers . J. Chem. Phys., 119, 1671-1682. 

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. 

The analysis takes place in a circular disc called the transfer disc or rotor (Figure 6.1) made of an inert material such as Teflon or acrylic whose surface properties allow minimal adhesion of liquid. It contains radially arranged sets of cavities, each set composed of two or more interconnected cavities, one for the sample and the others for the reagents (Figure 6.2). Small measured volumes of sample and reagent, e.g. 5 - 200/rl, are automatically pipetted into the appropriate wells so that each set contains a different sample but the same... 

The 6th material Is a condensation-cure product which has been previously used for medical Implant protection (I). As verified by lap shear tests, (described below), the first 3 elastomers provide minimal adhesion In the absence of a surface primer. The last 3 are self-prlmlng materials. To permit visual examination, we tried to select clear materials. All of the elastomers are clear except for types 5 and 6. 

Print table adhesive remover. Used to remove print table adhesives or renew adhesive surface tackiness. Minimal odor development in use. 

To reduce or eliminate debonding, a UV-polymerized, hydro-phobic sealant was painted around the dentin-methacrylate interface. Thus, it was hoped that hydrolytic degradation of the nd would be minimized. The rationale for this procedure is that the coating would seal off the adhesive from contact with water, or at least the water permeation through the protective film to the adhesive surface would be reduced. Suitable protective formulations should (1) cure within 1 minute, (2) be hydrophobic,... 

In the extrusion welding technique, the mating parts are heated by pressing onto a metal heater which is held at 250°C-270°C and which has been surface-treated (usually with PTFE) to minimize adhesion. For butt welding, the heater is a flat plate for spigot and socket welding, there are male and female surfaces. The ideal pressure on the hot surface is 50-60 kPa, and the time should be sufficient for the fusion of the material to a depth of 4-5 mm at the contact surface. The heating unit is removed and contact is made under a pressure of ideally 0.06 to... 

In comparison with metals, most conventional polymers are low in wear resistance. For wear control, we need to understand various wear mechanisms for each polymer system (V). As discussed in a previous paper, for adhesive wear, surface energetics can determine the extent of surface wear. Thus, a low surface energy is preferred to minimize the surface attrition. In addition, a harder polymer is desired to lower the wear rate. For abrasive wear, fracture energetics become important a harder and tougher material should be more wear resistant. 

With knowledge of the zones of surface energy that either favor or minimize adhesion In biological environments, it is now possible to design and develop improved prosthetic materials for a number of important applications. 

When the contact surfaces are greatly different in wettability (hydrophilic quartz particles on a hydrophobic paraffin wax substrate, or mastic or graphite particles on a quartz surface), the adhesion is minimal (adhesion number equal to zero). 

From the examples given here, it is evident that soil adhesion can be reduced by surface modification through the application of a coating that minimizes adhesion or by forming a layer of water between the contact surfaces. The adhesion depends on the soil moisture content and the soil particle size distribution. By changing the moisture content and by the use of electroosmosis, the adhesion of soil to solid surfaces can be reduced. 

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