Builds Slowly

The peak instantaneous value falls as the sources go off When more sources come on, with shift, it builds slowly and thus reduces rapid fluctuations of Q size. When Q changes rapidly, queuing models do not work well. 

In July 1978, AECL reorganized its operations into four companies - the Research Company (Chalk River) the Chemical Company (heavy water) the Engineering Company (for CANDU) and the Radiochemical Company, or RCC (formerly CPD). Acceptance of the new name for CPD was slow, however, and it did not come into general internal use until well into the 1980s. (To avoid confusion, CPD continues to be used in this chapter.) In the new CPD, sales of BTUs did not dominate as they once had industrial irradiation was building slowly, and molybdenum-99 was generating sohd sales. 

Economic Aspects. In 1994, there were 14 producing MDF mills in the United States. These mills produced 2.240 million m of product (2). The market for MDF in the United States is fairly weU saturated at this time and for this reason the industry is expanding only slowly. However, as noted herein, the world market is stiU growing rapidly and the manufacturers are building to satisfy this market. Currentiy, some U.S. manufacturers are also exporting MDF into these markets. 

Although the varied uses for which DIR couplers are employed call for precise control over where the inhibitor diffuses, the very complexation mechanism by which inhibitors work would seem to preclude such control. The desired ability to target the inhibitor can be attained by the use of delayed release DIR couplers, which release not the inhibitor itself, but a diffusable inhibitor precursor or "switch" (Fig. 16) (98). Substituents (X, R) and stmctural design of the precursor permit control over both diffusivity and the rate of inhibitor release. Increasing the effective diffusivity of the inhibitor, however, means that more of it can diffuse into the developer solution where it can affect film in an undesirable, nonimagewise fashion. This can be minimized by the use of self-destmcting inhibitors that are slowly destroyed by developer components and do not build up or "season" the process (99). 

In a countercurrent-type column contactor, stable operation is possible as long as the rate of arrival of droplets in any section does not exceed the coalescence rate at the main interface once this value is exceeded, droplet backup will occur at the interface and slowly build back into the column active area, a condition known as flooding. This is an inoperable condition. 

In some reactions, the situation kj > 2 exists. Under these conditions, the eoncentration of the intermediate will build up as it goes on more slowly to product. The possibility of isolating, or at least observing, the intermediate then exists. If both kj and k2 are large, the reaction may proceed too rapidly to permit isolation of the intermediate but spectroscopic studies, for example, should reveal the existence of two distinct phases for the overall reaction. It should be possible to analyze such a system and determine the two rate constants. 

Initially, the water slowly reacts with the isocyanate. However, the reaction can be catalyzed with an appropriate catalyst, such as dibutyltin dilaurate or a morpholine tertiary amine catalyst. The isocyanate will react with water to form a carbamic acid, which is unstable and splits off carbon dioxide, to produce a terminal amine end group (see p. 76 in [6]). This amine then reacts with more isocyanate-terminated prepolymer, as shown above, to form a polyurea. This process repeats itself, building up molecular weight and curing to become a polyurea-polyurethane adhesive. 

Chemical Reactivity - Reactivity with Water Reacts slowly, forming heavy scum and liberating carbon dioxide gas. Dangerous pressure can build up if container is sealed Reactivity with Common Materials No hazardous reaction unless confined and wet Stability During Transport Stable if kept sealed and dry Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor qf Polymerization Not pertinent. 

Rusting indoors and in enclosed spaces Although much of what has been written above is of general application, the experimental data apply specifically to exposure outdoors. The conditions of exposure indoors are somewhat different, because the steel is not exposed to rain and direct sunlight. Rusting depends on the condensation of moisture, which may evaporate from the surface much more slowly under enclosed conditions than outdoors moreover, the rust tends to remain on the surface and may build up in time to a thick scaly layer. 

Zinc Zinc surfaces corrode more slowly in the country than in either marine atmospheres or in industrial areas where sulphur pollution constitutes the main danger both to them and to many other building materials. 

Deposits of lead sulfate slowly build up on the plates, partially covering and replacing the lead and lead dioxide. 

During the preliminary work one should remain alert for signs of unexpected complications. For example, does the reaction proceed to completion Do competing reactions occur Is there any indication of an intermediate being formed Does the product build up more slowly than the reactant disappears Early recognition of these and similar features leads to more effective work. 

FIGURE 13.1 Reactions proceed at widely different rates. Some, such as explosions of dvnamite, are very fast. Charges have been set off to demolish this old building. The chemical reaction in each explosion is over in a fraction of a second the gases produced expand more slowly. 

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