Metallic flop

Attempts to correlate various rheological parameters to good metallic appearance have not been found to be successful [91]. However, in the case of four samples with varying metallic flop index values, it has been observed that higher degree of pseudoplasticity led to a better flake orientation when compared to samples with lower metallic flop index values. (Fig. 7-4)... 

Fig. 7-4 Viscosity versus shear rate, metallic flop index values sample A 62, sample B 57, sample C 58, sample D49.

This isoindoline nickel complex pigment is mainly recommended for the coloration of metallics and effect coatings, especially for water based systems. P.R.271 affords yellowish to medium red shades, providing a bright flop in metallics. Alkyd/melamine resin systems may safely be overcoated and withstand exposure of 140°C for 30 minutes. The flow properties of P.R.271 in these systems and in polyester cellulose acetobutyrate base coat systems are good, but there is a certain tendency to flocculate. 

In the second part of Eq. (6.155), the electric field has been written as X - M/eeQ-Let s have a closer look at Eq. (6.154). It involves the toms (AG )f and (AG )j,. Is there any difference in the chemical energy of the flipped and the flopped molecules In other words, if the molecules are the same (i.e., water), should their chemical interaction with the substrate not be the same Would they not cancel out Certainly not. Evidence exists proving that water molecules are preferentially adsorbed with their oxygen aid toward the metal at the pzc (see Section 6.7.8). This means that the chemical interactions between the two states of water—flip-up and flop-down molecules—and the metal are different. The flipped dipoles, with their oxygens toward the metal, are more stable, and should have a more negative chemical energy. Thus, l(AG°) l > (AG°)jJ and the difference between these two terms is... 

The anisotropy of the pigment particle causes orientation along the flow pattern. If the flow pattern is parallel to the surface, an increased brilliance is achieved even to a degree that a flop effect can be observed, as in painted objects. On the other hand, flow disturbances and the merging of resin of different temperatures are frequently accentuated by metallic pigments through flow and weld lines. 

To calm myself, I dipped my hands in the pail of water. The sight and feel of the metal reminded me of home and Mrs. Gill. Everything she touched got clean in the end. Then I had a good idea—I d wash the babies anyway. That s what you did with the dead. So I picked up a baby and lowered her into the bucket, but her head on its thread of a neck flopped onto my wrist and then down into the pail, dragging the rest of her body with it. 

This behavior also leads to another typical optical property of the metallic effect the flop- or two-tone-effect. This effect describes the fact that, at metallic effect coatings. 

The physical parameters for the metallic effect, which influence the ratio between reflection and scattering and thereby the flop effect, the lightness and brightness, the brilliance and sparkle, the gloss and the distinctiveness of image (DOI) etc. etc. can simply be described in terms of particle size, particle shape (morphology), particle size distribution and particle orientation in the film... 

As the particle size of the individual flakes plays a significant role in generating the metallic effect, the particle size distribution is even more important to describe the total effect the smaller the share of fine and ultra-fine particles, the higher will be the brightness, brilliance and flop, as well as the chroma in tinted systems. 

On the other hand, a poor orientation results in an irregular reflection, causing salt and pepper effects , cloudiness and a poor metallic effect and flop (Figure 5.33). A disorientation of the flakes can be created if either too wet films (or too slow-drying solvents) or too dry films (or too fast-drying solvents) are applied. 

All the optical measurements for characterizing the metallic effect should be carried out with goniophotometers and/or goniospectrophotometers to take the flop effect into account [5.176-5.181]. 

Figure 17 Time course of the kinetic experiment performed with surfactant substrate (19) in vesicular 20, Br upon addition of Cu(NO3)2 ([copper(II)] = 5 x 10 M, pH 5). The first part was run at 25 °C, i.e. above the of the membrane. At this temperature the kinetics are monophasic. The second part was run at 10 °C. If during the time at 25 °C copper(II) permeation occurred, monophasic kinetics would be expected since all the substrate (in the internal and external layers) is exposed to the metal ion. Since a biphasic process is observed, no permeation has occurred and the stay of the vesicles above f involves only flip-flop of (19)...

Fig. 16. The rope jumping motion of the N04 crown of the functionalized calix[4]arene 10 on the coordinated Ag(I) ion. The flip-flop movement results from the fact that the N04 ring has too small an aperture to encompass the metal ion. In a CH2CI2/CH3OH solution (4 1 v/v, deuterated solvents) the oscillating motion slows down with temperature and stops at -20 °C...

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