Dy systems

Azobisnittiles are efficient sources of free radicals for vinyl polymerizations and chain reactions, eg, chlorinations (see Initiators). These compounds decompose in a variety of solvents at nearly first-order rates to give free radicals with no evidence of induced chain decomposition. They can be used in bulk, solution, and suspension polymerizations, and because no oxygenated residues are produced, they are suitable for use in pigmented or dyed systems that may be susceptible to oxidative degradation. 

Dye and pigment effects on polymers as well as their inherent stability are still subjects of considerable complexity and interest. Additive effects on the stability of dyed systems have been reviewed as has general dye photofading. ... 

Fig. 7.12. Magnetic phase diagram for the Er-Dy system [after Koehler (1972)].

Considering the above presented data it is possible to predict the existence of one liquid and two solid rows of continuous solutions in the Sc-Tb and Sc-Dy systems like in the Sc-Gd system. The occurrence of two of these solid solutions (aSc, aTb) and (aSc, oDy) has been already confirmed experimentally. 

Such a high-quality icosahedral phase was not only observed in the Zn-Mg-Dy system but also identified in several Zn-Mg-R alloys. Figure 110 shows the X-ray diffraction... 

Markova et al. (1971) reproduced the phase diagram for the Gd-Dy system and two other binary rare earth alloy systems in a report deahng with alloys of the lanthanide metals and yttrium, but did not reveal the source of their diagrams. Levitin et al. (1974) also showed this phase diagram and cited Markova et al. Details of the investigation that produced these diagrams were not found. 

The phase diagram for the Gd-Dy system as presented by Markova et al. showed six data points that formed a smooth curve defining the solidus of the system. This solidus has a slight downward curvature and the liquidus was drawn as a dashed straight line that connected the melting points of the end-members. Dashed solvus lines having a small gap between them indicated the probable temperature-composition relationship for the hep bcc transformation but no data were presented in support of these lines. 

Dysprosium and gadolinium are both trivalent lanthanide metals with atomic numbers that differ by 2 (Z = 66 and 64, respectively). Therefore, when prepared from high purity metals, alloys in this system would be expected to exhibit ideal behavior (see section 2.1.1). The phase diagram for the Gd-Dy system, shown in fig. 79, reflects the expected phase relationships for alloys prepared from high purity... 

In practice, 7s 7sv is negligible as is dys/dT for systems having large contact angles. Also, low energy surfaces have a relatively constant value of dyst/dT = 0.07 0.02 erg cm K , leaving... 

Ma.ke-Rea.dy, Because pressure is needed for ink wetting and transfer and because the image elements in letterpress vary in size, the same amount of printing pressure or squeeze exerts more pressure on highlight dots than on shadow dots. This necessitates considerable make-ready to even the impression so that the highlights print correctly and do not puncture the paper. Precision plates and premake-ready systems have helped reduce make-ready time, but it is still appreciable for quaUty printing and is a reason letterpress has been largely replaced by other processes. 

There are instances in which one manufacturer may designate a bluish red dye as Red 4B and another manufacturer uses Violet 2R for the same dye. To resolve such a problem the manufacturers pattern leaflets should be consulted. These show actual dyed pieces of cloth so the colors of the dyes in question can be compared directly in the actual appHcation. Alternatively, colors can be specified in terms of color space coordinates. The Cielab system is becoming the standard in this system the color of a dye is defined by three numbers, the L, a, and b coordinates (see Color). 

Colloidal Ti02 dyed with Coumarin 343 [55804-65 ] (9) is an extensively investigated system. 

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