Intensive drying

The high-intensity dry magnetic separators group may be cited as consisting of induced roll, crossbelt and ring-type separators. 

A sample decomposed explosively after intensive drying at 110° C. The aci-mtio-p-quinonoid salt may have been formed. 

Intensive drying of ammonia gas by passing it over the desiccant in a steel drying tube led to an exotherm, followed by a violent explosion. (An ammine derivative may have been formed). 

High impact polystyrene (HIPS), 11 466 20 353, 359-360 23 359, 368 antioxidant applications, 3 121 surface appearance of, 23 363-364 thermoforming of, 23 398—399 High intensity cross-belt magnetic separators, 15 454-455 High intensity dry magnetic separators, 15 450—452... 

Supercritical fluids have also been used purely as the solvent for polymerization reactions. Supercritical fluids have many advantages over other solvents for both the synthesis and processing of materials (see Chapter 6), and there are a number of factors that make scCCH a desirable solvent for carrying out polymerization reactions. As well as being cheap, nontoxic and nonflammable, separation of the solvent from the product is achieved simply by depressurization. This eliminates the energy-intensive drying steps that are normally required after the reaction. Carbon dioxide is also chemically relatively inert and hence can be used for a wide variety of reactions. For example, CO2 is inert towards free radicals and this can be important in polymerization reactions since there is then no chain transfer to the solvent. This means that solvent incorporation into the polymer does not take place, giving a purer material. 

Figure 14.17 Relationship between notched impact strength of PET compounds and their moisture content. The plot emphasizes the need for proper drying of PET resin to reduce the moisture content to below 200 ppm before melt processing. Intensive drying procedures are time-consuming and costly and therefore internal desiccants are often used...

One of the alleged hazards of drying, made much of in the 1920s and 1930s, can now be ignored safely. The efforts of one H. B. Baker purported to establish that intensive drying could alter the physical properties, in particular the vapour pressure, of certain liquids. The whole episode has been succinctly reviewed (Farrar, 1963), and the experience of many skillful workers over a further 25 years with systems far drier than Baker ever achieved, enables one to confirm Farrar s view that this was truly a mare s nest . 

The various modifications of sulphur trioxide will therefore act as mixtures of these three constituents. In an ordinary preparation the condition of equilibrium is more or less rapidly attained, but in an intensively dried material the velocity of such inner transformation is considerably retarded.1 On realising this condition, as already shown, both the solid and liquid states behave as mixtures. Exposure to X-rays accelerates the attainment of the inner equilibrium. 

Kistiakowsky finds that intensive drying makes no difference to the results. 

XII. Kistiakowsky has shown that when light is absorbed by intensively dried chlorine no appreciable part of it is re-emitted by fluorescence. Since, moreover, the total absorption is unaffected, it seems impossible that the... 

Now of reactions which are inhibited by intensive drying the majority, as we have seen, are between substances in... 

When storing the solid samples under the possible influence of moisture, the intrinsic viscosity, even after intensive drying, was significantly smaller than directly after polymerization. 

We have considered it necessary to add one more requirement to the adhesive it should glue under conditions of a moist operative area, because intensive drying of the tissues prior to glueing would not contribute to the normal occurence of regenerative processes. The manner in which this is achieved will be discussed below. 

Compared to water-another green solvent which is frequently adopted as a dispersing medium in industrial heterogeneous polymerizations-scC02 eliminates the need for energy-intensive drying processes, as the polymer product can... 

The effect of intensive drying is another example of the intimate relationship between colorant and turbidity. Depending on the conditions of drying, a sugar, crystallized from a colored but brilliant solution and then dried, may give a turbid solution when redissolved. The type of inorganic ions present has a decided effect on the extent of this phenomenon, in a manner not yet completely clear, but the extent is certainly related to the valence and coordinating power of the ions. 

With moist oxygen in closed vessels the reaction may proceed explosively, but it does not proceed at all when the gas and the oxygen are intensively dried. The gas was slowly absorbed and hydrolysed by water, more rapidly by alkalies, thus —... 

Summary.—In three experiments described here no abnormal rise in the boiling points of benzene and carbon tetrachloride was obtained after four to four and a half years of intensive drying. The organic liquids were sealed off with phosphorus pentoxide in glass tubes and kept at room temperature. 

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