Mechanical rubbing

Franklin defined charge as positive or negative in the way we understand the loss or gain of electrons by mechanically rubbing surfaces together. His definition still stands. 

The control of leakage loss across die blades in a reaction expander is extremely important. Maintaining adequate clearance implies preventing mechanical rubs while at die same time minimizing die loss effect on expander efficiency. 

With the exception of mechanical rub, defective cables and transducers are the only sources of this ski-slope profile. When mechanical rub is present, the ski slope will also contain the normal rotational frequencies generated by the machine-train. In some cases, it is necessary to turn off the auto-scale function in order to see the rotational frequencies, but they will be evident. If no rotational components are present, the cable and transducer should be replaced. 

The isotropic form has little graphitic characteristic and essentially no optical activity. It is composed of very fine grains without observable orientation and for this reason, it is known as isotropic carbon rather than isotropic graphite. It is often obtained in fluidized-bed deposition, possibly due to continuous surface regeneration by the mechanical rubbing action of the bed. An isotropic structure, observed by transmission electron microscopy, is shown in Fig. 7.4.111]... 

A weakening of the binding forces between the keratinized epithelium and the layer of grease via the reduction of the surface tension between the water and the water-resistant oil/grease. Because of this reduced surface tension, water (and surfactant molecules) can penetrate into the finest wrinkles of the skin. In this way, more and more interface is occupied by surfactant, and the adhesiveness of the soil-containing layer is further weakened, a process facilitated by mechanical rubbing. 

All polymer films were used as prepared, i.e. the samples were not mechanically rubbed. Samples that were contacted with other polymer sheets and afterwards separated, showed highly electrically charged surfaces which cannot be studied by the AFM techniques mentioned below. 

Heil, H. et al.. The influence of mechanical rubbing on the field-effect mobihty in polyhexylthiophene, J. Appl. Phys. 93, 1636-1641, 2003. 

Figure 12.12. Fabrication of a parallel nanocylinder array in bulk films of a PEO-based azo LCBC by the mechanical rubbing technique. All the PEO nanocylinders are oriented along the rubbing direction. Source Reproduced with modifications from Yu et al., 2006b.

Hartmarm, L., Tremel, K., Uttiya, S., Crossland, E., Ludwigs, S., Kayunkid, N., Vergnat, C., Brinkmann, M., 2011.2D versus 3D crystalline order in thin films of regioregular poly(3-hexylthiophene) oriented by mechanical rubbing and epitaxy. Adv. Funct. Mater. 21,4047-4057. 

The tester consists of four specimen holders of 100 nun diameter placed over inclined cups with a rotating mechanism rubbing the underside of specimens, as shown in Fig. 2.12. Specimens are subjected to simulated rain from a height of 150cm using filtered water under pressure. Water penetrating through the fabrics is collected in the cups and is measured on mass basis. 

The mechanical rubbing action of the repeated manual cleaning impairs the stencil surface. This is particularly apparent with plastic stencils. These changes to the stencil surface can result in misprints and shorten the service life of the stencil, making it very difficult to track the source of the problem. 

Thermally switched liquid crystal alignments can be obtained with a rubbed PVK film [70]. A mechanically rubbed PVK layer can induce a planar alignment of liquid crystals with their axis direction perpendicular to the direction of rubbing. This direction can be switched toward the rubbing direction by a thermal treatment. A possible application of such a device is for polarization rotators. The PVK film does... 

Today, most field effect liquid crystalline displays (LCDs) use alignment layers to achieve high contrast ratio and maximum brightness (26). The conventional alignment technique is mechanical rubbing, in which a substrate is coated with a thin polymer film and then buffed with a cloth to control the direction of liquid crystal on the substrate surface. 

Abrasion Resistance. The ability of a material to resist mechanical rubbing. Some ceramic products are specially made to have this property, for example blue engineering bricks for the paving of coke chutes. There are several types of apparatus for the evaluation of this property see bender abrasion... 

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