Marginal regeneration

Margaric acid, physical properties, 5 29t Marginal failure, 26 982 Marginal regeneration process, 12 13 Margin of exposure, 25 244 Margin of safety determination, 25 234-235... 

Buzza et al. (105) have presented a qualitative discussion of the various dissipative mechanisms that may be involved in the small-strain linear response to oscillatory shear. These include viscous flow in the films. Plateau borders, and dispersed-phase droplets (in the case of emulsions) the intrinsic viscosity of the surfactant monolayers, and diffusion resistance. Marangoni-type and marginal regeneration mechanisms were considered for surfactant transport. They predict that the zero-shear viscosity is usually dominated by the intrinsic dilatational viscosity of the surfactant mono-layers. As in most other studies, the discussion is limited to small-strain oscillations, and the rapid events associated with T1 processes in steady shear are not considered, even though these may be extremely important. 

Marginal regeneration is shown schematically in Figure 8.4. The thicker film is drawn into the border by the negative excess pressure AP and the thinner film is pulled out of the border (Figure 8.4a). Figure 8.4b shows a schematic view of the... 

Fig. 8.4. Representation of marginal regeneration (a) film drawn fron thicker to thinner film (b) schematic view of the film (c) close-up of flows in the plateau border of the film.

Marginal regeneration is probably the most important cause of drainage in vertical films with mobile surfaces, i.e. with surfactant solutions at concentrations above the c.m.c. 

A related phenomenon to asymmetric drainage in horizontal cylindrical foam films is that of the so-called marginal regeneration. This process occurs in vertical foam films subject to both capillary suction from the Plateau borders and gravity. It is manifest as an apparent turbulent motion on the margin of foam films where thin elements of film are drawn out of the Plateau border and thick elements are sucked... 

It should be clear then that asymmetric drainage of horizontal cylindrical films and marginal regeneration in vertical foam films, although often apparent, are not always exhibited. Liquid flow by capillary suction from the Plateau border is. 

Nierstrasz, VA. Marginal regeneration, PhD Thesis, Delft University of Technology, 1996. 

This polyethoxy-polypropoxy block copolymer is more snrface active than the protein and radically alters the vertical foam film drainage behavior of solutions of the latter. The extremely slow rigid film drainage behavior (presumably with suppressed marginal regeneration) of the BSA solntions was shown by Nemeth et al. [132] to be replaced by relatively rapid, apparently mobile, drainage behavior in the presence of copolymer. These vertical films were, however, unstable with lifetimes of the order of a... 

A vertical simple mobile film draining along a border due to marginal regeneration and gravity convection... 

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