Fusion conditions

Substitution of various groups by amino or hydroxyl functions is industrially unimportant for the production of 2- and 4-aminophenol, but this type of reaction is used for the synthesis of 2- and 4-aminophenol derivatives. However, 3-aminophenol caimot be obtained easily by reduction. It is made by the reaction of 3-aminobenzenesulfonic acid [121 -47-1] with sodium hydroxide under fusion conditions (5—6 h 240—245°C). The product is purified by vacuum distillation (25). 

The methods of choice for beryUium oxide in beryUium metal are inert gas fusion and fast neutron activation. In the inert gas fusion technique, the sample is fused with nickel metal in a graphite cmcible under a stream of helium or argon. BeryUium oxide is reduced, and the evolved carbon monoxide is measured by infrared absorption spectrometry. BeryUium nitride decomposes under the same fusion conditions and may be determined by measurement of the evolved nitrogen. Oxygen may also be determined by activation with 14 MeV neutrons (20). The only significant interferents in the neutron activation technique are fluorine and boron, which are seldom encountered in beryUium metal samples. 

The preparation of derivatives of this ring system has also been achieved by reaction of substituted piperazines with urea. Reaction of the starting piperazinone (284) with urea under fusion conditions gives the desired ring system (285) (66CPB194). 

The same mixtures of reactants were diluted with water and heated in a stainless steel bomb at 225°-230°C. for the same length of time, but results were not as good as under the fusion conditions. No conditions gave results worth pursuing. 

The process for converting the vegetation sample to a soluble form is selected for convenience, familiarity, safety, and optimal removal of interfering substances. A problem in dissolving salts of heavier Group IIA elements with mineral acids is that they may be insoluble sulfates. The most common method for bringing insoluble sulfates into solution is to subject the sample to hydroxide-carbonate fusion (fusion is discussed in Section 4.6.2 of your Radioanalytical Chemistry text). The fusion is performed in a metal crucible that is relatively insoluble under the fusion conditions. The temperature must be sufficiently high to melt the sulfates and convert them into carbonates. The carbonates are then dissolved to prepare the sample for analysis. 

This set of standards was prepared from one very well analyzed and relatively pure gypsum specimen. The specimen was calcined and spiked with pure oxides and chemicals (Table 3) to alter its composition. The choice of the additives used for the spiking is critical. The compounds must be thermally stable under the fusion conditions and dissolve well in the molten borate flux. The oxygen balance of the specimen should also be maintained. 

Transmission electron microscopy. A representative micrograph of an area of a calcined model catalyst showing the formation of overlayers is displayed in Fig. 3. Such overlayers were observed in 4 of 7 areas studied, and were formed after calcination on both the W03 crystallites (marked 1 ) and on the Pt crystallites (marked 2 ). Other results described in detail elsewhere [6], indicate that after reduction overlayers spread, and HTBs formed. Overlayers do not form on Pt in the absence of W03, and they disappeared upon exposure to the electron beam. Possible carbon and silica contamination did not affect over layer formation. The overlayers observed on the model catalysts were not detected on the real catalyst, in part due to lack of constrast, and in part because dif-fusional conditions that facilitate overlayer formation, are greatly diminished 1n the real catalysts. Consequently the model catalysts represent a highly exaggerated view of events that occur at a much smaller scale in the real catalyst. 

The reduced materials (category (f)) require special fusion conditions because dissolution produces an exothermic reaction that can destroy the platinum alloy fusion vessels. For example, the flux used for sihceous materials is reconstituted as lithium tetraborate and hthium carbonate. A SiC or other reduced sample is mixed with lithium carbonate and sintered on top of a protective layer of lithium tetraborate that has been fused and spread over the dish. The weight of the reduced sample therefore needs to be adjusted to maintain the flux to a (oxidized) sample ratio at 5 1. If samples lie in category (c), lithium tetraborate is replaced by boric oxide, which together with the lithium carbonate will ultimately give the appropriate lithium tetraborate/sample ratio (ignited basis). 

The other popular type of electrofusion joint is the service saddle joint. This is used to make tee connections between a small diameter service and a larger diameter main pipe. These were also originally heated tool type welds but electrofusion reduces operative involvement and provides a greater level of control in fusion conditions. The technology has also been extended to larger size saddle connections that produce pipe branches that can be made whilst the main pipe is still under pressure. 

A cross section of the lon-Ring-Compressor reactor is shown in Fig. 10, and estimated parameters are given in Table 11. As with the FRC moving-ring reactors, the rings are formed and compressed to fusion conditions, passed through a burner section, and recovered by the inverse of formation. 

It is essential to have a safe process during the whole bioplastic life cycle. PHB has been described as the first real thermoplastic example obtained from a biotechnological process that is actually biodegradable. Although PHB is stable in a natural environment, its degradability rate is very high under processing and fusion conditions. 

The main weakness of FM steels regarding their performance under irradiation is their pronounced hardening and embrittlement when they are irradiated at low temperatures. This issue is particularly important for the water-cooled fusion reactor concept, since in that case the stmctural steels are expected to operate in a temperature range (300—350°C) where embrittlement was foimd to be most severe, and enhanced due to the high hehum production under fusion conditions. 

The above fusion conditions were adopted to determine oxygen in molybdenum prepared by sintering under hydrogen. The samples (diameter 15 mm, thickness 1 mm, weight 1.85 to 1.95 g) were irradiated together with the standards... 

When a crystallizable dispersed phase is used, fiactionated crystallization may occur. In such a confined polymer phase, the composition and surrounding conditions will play a major role in the crystallization processes. The structures of the aystals formed are defined by the following factors MW, microstructure of the polymer chain fusion condition prior to crystallization, miscibility, etc., therefore, to effectively develop polymer blends with improved crystallinity, the necessary factors must be carefully considered. 

A well-fused plastisol resolves both of these issues. Much less gas will escape from the foam, and the cell walls have enough elasticity to maintain their cell structure, yielding lower product density, good cell structure, and consistent physical properties in the final product. Care must also be taken to ensme that the plastisol is not too thoroughly fused when the azodicarbonamide gas decomposition begins. A ftiUy fused product will resist cell expansion more so than one with less complete fusion. The fusion conditions necessary to obtain maximum cellular expansion are extremely formulation dependent and are best determined experimentally. 

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