Surface forces reduction

Levins J M and Vanderiick T K 1992 Reduction of the roughness of siiver fiims by the controiied appiication of surface forces J. Rhys. Chem. 96 10 405-11... 

Because the surface energy per volume is larger for small particles and because the fundamental driving force for sintering is surface-energy reduction, compacts composed of smaller powders will typically sinter more rapidly. Smaller powders are more difficult to produce and handle therefore, predictions of sintering rate dependence on size are used to make choices of initial particle size. Herring s... 

For the analysis of extracellular glycolipids of respiratory tract, we have chosen the acellular material lining the alveoli of mammalian lungs. This unique lipid-protein mixture, responsible for the reduction of alveolar surface forces during respiration,... 

Adsorption. Sulfur and phosphorus ratios change with rubbing time. Tribofilms accumulated on the surface become thicker with time. All co-additives cause reduction in ZDDP surface coverage under all conditions studied. A surface force apparatus (SFA), and atomic force microscopy were used to determine tribofilm thiclaiess, molecular structure and mechanical properties. For the neutral ZDDP, monomolecular layer thickness is 1 nm and for basic ZDDP it is 1.6 nm (Sutherland et al., 1993 Bames et al., 2001 Bee et al., 1999 Dacre and Bovington, 1983 Georges et al., 1998 Paddy et al., 1990 Wu and Dacre, 1997). 

A qualitative model for lubrication of the condensed alcohol layer is not fully developed yet. We present here the best qualitative model based on the literature. As the applied pressure is very large and the scanning speed is very low in AFM, one can rule out the hydrodynamic lubrication even in the presence of condensed alcohol layer on the substrate. The AFM tip and substrate interface must be in the boundary lubrication regime. Figs. 7-10 show that the adhesion force reduction upon alcohol adsorption is accompanied by reduction of the friction force. Part of the adhesion force reduction is because of the surface tension decrease of the water layer on the substrate. When alcohol is dissolved in water, the surface tension decreases significantly because of segregation of alcohol molecules to the liquid-air interface. ... 

The effect of polymer brushes on the reduction of sliding friction was also observed for solid friction, using surface force apparatus (SEA) measurements [83-86]. For example, Klein et al. reported a massive lubrication between mica surfaces modified by repulsive polyelectrolyte brushes in water [83]. These results show that polymer dangling chains on solid or gel surfaces can dramatically reduce the surface friction if the polymer brush has a repulsive interaction with the sliding substrate. 

Consider a molecule diffusing in free space or a solute molecule diffusing in solution. Upon colliding with a surface, assume that the molecule is sufficiently entrained by surface forces that there results a reduction in dimensionality of its diffusion space from d = 3 to d — 2, and that in its subsequent motion the molecule is sterically constrained to follow the pathways defined by the lattice structure of the surface (or, perhaps, the boundary lines separating adjacent domains). If at some point in its trajectory the molecule becomes permanently immobilized, either because of physical binding at a site or because an irreversible reaction has occurred at that site, then, qualitatively, this sequence of events is descriptive of many diffusion-reaction processes in biology, chemistry and physics. 

Several mechanisms have been identified that are responsible for the production of oil from a steam drive. These include thermal expansion of the erode oil, viscosity reduction of the crude oil, changes in surface forces as the reservoir temperature increases, and steam distillation of the lighter portions of the crude oil. 

---