Synthesis of an ultradispersed diamond phase during detonation of composites

Conclusion We have attempted to analyze the synthesis of the diamond phase during, the detonation of secondary explosives by comparing the results of an explosion experiment with data obtained by studying preserved UDD powders.These data show that during detonation the growth in the UDD particles is a strongly limited process that is essentially independent of the size of the explosive charge or the external cooling conditions. The size distributions of diamond particles formed during direct synthesis from the carbon contained in the molecular structure of the explosive and during dissociation of inert organic substances are in satisfactory agreement with a lognormal distribution. The thermodynamic conditions during synthesis determine the dispersivity of the product UDD particles and this must be taken into account in thermodynamic detonation calculations. The effect of the different constituents of the, explosive on UDD synthesis (heat and mass transfer) is strongly limited.These data may support the concept of detonation in secondary explosives as a set of relatively fast and much slower reactions [25, 26] where, in the case of composites, the coagulation of carbon released during decomposition of each component separately and diffusion processes among the components may both act as slow exothermic reactions.Novosibirsk. Translated from Fizika Goreniya i. Vzryva, Vol. 29, No. 1, pp. 120–128, January–February, 1993.     

The use of direct osmosis tests as complementary experiments to determine the water and salt permeabilities of reinforced cellulose acetate membranes

In this article the use of the direct osmosis test as a complementary experiment to the reverse osmosis test is described. The membranes investigated are cellulose acetate membranes reinforced with mineral fillers. In both tests the same influence of the type of fillers on the water permeability coefficients is found. The salt permeability coefficients indicate the presence of pressure sensitive defects in the reinforced membranes. The direct osmosis test is found to be a suitable test to confirm and predict the membrane properties under reverse osmosis conditions.     

Technological parameters of corundum chamotte

Conclusions It has been established that to obtain densely sintered macrocrystalline corundum chamotte it is most expedient to obtain the briquet in the form of granules 20–25 mm in diameter from finely ground GK alumina (or special alumina brands of high purity) followed by annealing at 1900–1950°C.Translated from Ogneupory, No. 3, pp. 31–36, March, 1980.     

Grafting of nylon 66 with methyl methacrylate using dimethylaniline–benzyl chloride–acetic acid initiating system

Grafting of nylon 66 with methyl methacrylate (MMA) under the initiating influence of dimethylaniline (DMA)–benzyl chloride (BC)–acetic acid (AC) mixture was studied to discover optimal conditions for grafting. Results of this investigation showed that a mixture of water/ethanol at a ratio of 90:10 constitutes the most favorable medium for the grafting reaction. Optimal grafting occurred when a concentration of 0.16 mole/l. DMA plus 0.17 mole/l. BC plus 0.2 mole/l. AC was used. Using lower or higher concentrations of this initiator led to lower grafting. On the other hand, increasing MMA concentration brings about a significant increase in the graft yield. The same holds true for reaction time and temperature, though an induction period was observed at a lower temperature (65°C) and when lower monomer concentration (2%) was used.     

H2S/Halogen promoted oxidative dehydrogenation of butene-1

An experimental program was carried out to determine the effectiveness of H₂S/mixed halogen promoters in the oxidative dehydrogenation reaction. Using the butene-1 to butadiene reaction as an example it was found that while H₂S or any of the hydrogen halides alone could be used as the promoter, superior conversions and selectivities (80–85%) were obtained when H₂S was used in admixture with the halogens, preferably HCl and/or HBr. The effect of different catalysts and some processing variables (temperature, space velocity) on the desired reaction will be presented.     

Application of Porous Glasses as Matrices for Nanocomposites

The use of matrices of different types makes it possible to prepare nanocomposites differing in the degree of ordering, the size and shape of structural units, their spatial distribution, and the type of contact between them. Porous glasses with controlled characteristics of pores can be used as matrices for nanocomposites. This provides a means for determining the basic parameters and the main properties of nanoclusters as a function of the size of their structural units. It is shown that the structural parameters of porous glasses can be controlled by varying the conditions of thermal and chemical treatments of the initial glasses.Original Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Aleksashkina, Venzel, Svatovskaya.     

Technical new feature

A continuous process for the commercial production of isopropenyl stearate (IPS) from triple pressed stearic acid and a stabilized form of propyne has been developed. Cost estimates, including capital costs, operating costs, and profitability, for commercial scale plant production which show the process to be economically feasible are presented. This potentially profitable process offers the advantages of reliable raw material sources, minimal external thermal requirements, and usable process waste streams. For a plant producing 5 million pounds of IPS per year, the selling price range is 80 to 107 cents/lb IPS, corresponding to a raw material cost range of 27 to 54 cents/lb of IPS. For a 20 million pound per year plant, the selling price range is 58 to 85 cents/lb IPS. The selling prices include a 20% annual return on fixed capital investment. Fixed capital requirement ranges from 2.7 to 10.9 million dollars (3rd quarter, 1975) for plants ranging in size from 5 to 50 million pounds of IPS per year, respectively.     

Graft copolymerization of vinyl monomers on modified cottons. VI. Vinyl graft copolymerization initiated by manganese (IV)

The ability of potassium permanganate in the presence of different acids to induce grafting of methyl methacrylate and acrylonitrile onto sodium hydroxide-treated cotton, partially carboxymethylated cotton, partially cyanoethylated cotton, and partially acetylated cotton was investigated. The copolymerization reaction was carried out under a variety of conditions. The graft yields are greatly enhanced by increasing concentration of monomer, reaction time, and temperature. The opposite holds true for initiator at higher concentrations. The effectiveness of the acids was: nitric acid > sulfuric acid > perchloric acid > hydrochloric acid. The change in the physical and/or chemical structure of cellulose by its modification via etherification reaction or esterification reaction had a significant effect on the susceptibility of cellulose toward grafting. While partial carboxymethylation or partial cyanoethylation of cellulose prior to grafting increased the graft yield, partial acetylation caused a decrease.     

New method of determining the slag-resistance of refractories

Conclusions A new method is proposed for determining the slag resistance of refractories with lever apparatus which is qualitative.The new technique permits the specific features of the destruction of refractories by slags to be determined, and explains the mechanism of this process by mineralogical analysis and by describing the external appearance of the changed specimens.Data on the changes in the specimens during tests and the compositions of the zones will be given in the next article.Data obtained by the new method show that the slag destruction of refractories accelerates with time.     

Foamed nitride-bonded silicon carbide refractories

Conclusions We obtained foamed silicon carbide insulating material with a nitride bond. The nitride bond is formed from a mixture of silicon nitride of the- and-modifications upon reaction with nitrogen. The formation of the nitride commences at about 1200°, and is practically complete at 1450°; the rate of nitriding of the foam ceramic is much greater than in dense specimens. The material has a homogeneous phase composition which is an advantage compared with foamed silicon carbide containing a complex bond obtained in carbon fillings.The foamed insulating brick based on nitride bond possesses a high thermal-shock resistance and structural strength at elevated temperatures. The strength is increased with an increase in the apparent density. The material is characterized by moderate mechanical strength, typical for silicon carbide refractories of this type [1, 3, 4].The foamed silicon carbide brick with a nitride bond can be recommended for service at high temperatures in nonoxidizing atmospheres when substantial thermal-shock resistance is required.Translated from Ogneupory, No. 7, pp. 48–51, July, 1970.