Sublimation resists

Cl Disperse Violet 26 is prepared by the reaction of l,4-diamino-2,3-dichloroanthraquinone (Cl Disperse Violet 28 (35)) with potassium phenoxide in phenol as a solvent at high temperature. Introduction of phenoxy groups into the 2,3-position shifts the shade to bright, reddish violet and improves the lightfastness and sublimation resistance. 

The basic type of dye closely resembles that used for dyeing polyester fibers, but the selection of compounds is based on other criteria. Requirements regarding sublimation resistance are not as stringent, whereas fastness to ozone, exhaust gases, and washing are important. Substitution by amino, and especially by alkyl-amino, groups tends to decrease lightfastness of the dyes in polyester fibers. This is not the case for acetate and polyamide fibers. 

OUTSTANDING PROPERTIES reduce friction adhesion forces, form a thin films on surface of the finish products giving excellent slip effect, improve filler dispersion, high film clarity, color stability, heat sublimation resistance... 

Properties. Under nitrogen pressure hexagonal boron nitride melts at about 3000°C but sublimes at about 2500°C at atmospheric pressure. Despite the high melting point, the substance is mechanically weak because of the relatively easy sliding of the sheets of rings past one another (3). The theoretical density is 2.27 g/mL and the resistivity is about 10 H-cm. 

Sublimation (diffusion) printing is a textile process in which color patterns in dry die crystals are transferred from a release film to the fabric under high heat and pressure. The process has been adapted to plastics. The equipment used is very similar to that used for hot stamping. Under heat and pressure, the dye crystals sublime (go directly to the vapor phase from the solid phase without melting) and the vapor penetrates the plastic product. As a result, the decoration is very durable and wear resistant. It is also cost competitive against other processes such as two-step injection molding or silk screening. 

Like graphite, h-BN is soft and lubricious and it has a low density. It is a refractory material which sublimes at 3000°C and has exceptional chemical resistance. The characteristics and properties of CVD h-BN are shown in Table 10.2. 

In addition to chemical reactions, the isokinetic relationship can be applied to various physical processes accompanied by enthalpy change. Correlations of this kind were found between enthalpies and entropies of solution (20, 83-92), vaporization (86, 91), sublimation (93, 94), desorption (95), and diffusion (96, 97) and between the two parameters characterizing the temperature dependence of thermochromic transitions (98). A kind of isokinetic relationship was claimed even for enthalpy and entropy of pure substances when relative values referred to those at 298° K are used (99). Enthalpies and entropies of intermolecular interaction were correlated for solutions, pure liquids, and crystals (6). Quite generally, for any temperature-dependent physical quantity, the activation parameters can be computed in a formal way, and correlations between them have been observed for dielectric absorption (100) and resistance of semiconductors (101-105) or fluidity (40, 106). On the other hand, the isokinetic relationship seems to hold in reactions of widely different kinds, starting from elementary processes in the gas phase (107) and including recombination reactions in the solid phase (108), polymerization reactions (109), and inorganic complex formation (110-112), up to such biochemical reactions as denaturation of proteins (113) and even such biological processes as hemolysis of erythrocytes (114). 

The product temperatures were -21.2°C for KC1 and -31.0°C for povidone. The arrows mark the values of the vapor pressure of ice at the operating temperatures. The normalized dried product resistances increase smoothly with pressure as the vapor pressure of ice is approached and exceeded. Thus, the sublimation rate decreases smoothly throughout this pressure range and does not drop to zero at a total system pressure which exceeds the vapor pressure of ice. This observation is completely consistent with the theoretical concepts developed... 

Most of the work initially was with the more volatile transition metals, i.e. the first row metals plus palladium, silver and gold, because these were easy to evaporate in reasonable quantities in simple apparatus. However, efforts to use the less volatile metals of the second and third rows gained momentum. Skell used sublimation of resistively heated wires of molybdenum and tungsten to make the remarkably stable [Mo(rj4-C4H6)3] and [W(1j4-C4H6)3] (42). Green... 

A plant having a shelf area of = 30 m2 has been loaded with 300 kg of water in trays and frozen on the shelves. Water vapor transport and condenser temperatures have been measured in this case between 0.4 and 0.6 mbar, which is approx, two to three times higher than the normally expected operation pressure of the plant (to get an measurable quantity of ice sublimed in a reasonable test time). The data of the test are shown in Fig. 2.19. Three Pt 100 (resistance thermometers) have been frozen in the ice. One CA each have been... 

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