Paste consistency

The early 1980s saw considerable interest in a new form of silicone materials, namely the liquid silicone mbbers. These may be considered as a development from the addition-cured RTV silicone rubbers but with a better pot life and improved physical properties, including heat stability similar to that of conventional peroxide-cured elastomers. The ability to process such liquid raw materials leads to a number of economic benefits such as lower production costs, increased ouput and reduced capital investment compared with more conventional rubbers. Liquid silicone rubbers are low-viscosity materials which range from a flow consistency to a paste consistency. They are usually supplied as a two-pack system which requires simple blending before use. The materials cure rapidly above 110°C and when injection moulded at high temperatures (200-250°C) cure times as low as a few seconds are possible for small parts. Because of the rapid mould filling, scorch is rarely a problem and, furthermore, post-curing is usually unnecessary. 

The ZOE impression paste is essentially a two-paste ZOE cement. One paste is formed by plasticizing the zinc oxide powder with 13 % of mineral or vegetable oil. The other paste consists of 12% eugenol or oil of cloves, 50% polymerized rosin, 20% silica filler, 10% resinous balsam (to improve flow) and 5 % calcium chloride (accelerator). 

Fig. 5.1 The composition of a paste consisting of C3A and gypsum in the presence of calcium chloride at various times (Tenoutasse). 

Normal concrete mixes resist being moved under pressure due to segregation of the cement paste that occurs when pressure is applied. Basically a pumpable concrete will have a suitable aggregate-void system and a cement paste consistency that will flow adequately through the void channels. Both these properties of the mix are required to meet the primary demands of pumpability which are ... 

The air-bubble generating and stabilizing process requires a minimum paste consistency. Silica fume particles are smaller than those of Portland cement and addition of silica fume therefore increases the fine fraction of the particles. The higher fraction of smaller particles then increases the surface area causing a greater binding of the water in the mix. This removes the water required for the bubble-generating process. 

Graham Explosive. It was prepd and used in a moist condition in the form of a paste consisting of K chlorate 51-8, sugar 25.9, K4Fe(CN) 20.7 Pb304 1.6%... 

Sthass, or the substanoe composing the imitation of precious atones, known as paste, consists of silica, potassa, with a still larger amount of oxide of lead, and colored by various materials. 

Stopin. Russ for Squib. Also refers to an igniter for pyrot and some expl compns. It consists of cotton thread which has been soaked in a coned soln of K nitrate and then coated with a paste consisting of pulverin (see Vol 8, P496-R) in gum arabic. Finally, it is coated with dry pulverin and subjected to slow drying. Its burning rate is 3 to 5m/sec Ref Gorst (1957), 124... 

The protective medium against fire discussed here is a water-insoluble mastic. Mastic is defined as a material of heavy paste consistency which can be applied with a putty knife, trowel, brush, or heavy duty spray equipment to yield a coating from 1/32 inch to one inch or more. These mastics are of mineral composition, bound by an organic resinous medium, and dry to ultimate hardness by the volatilization of an organic solvent. They are further characterized by high impact strength, and assistance to abrasion, water, and many chemicals. 

A small quantity of pure mercury is placed at the bottom of the vessel and covered with a layer of a paste consisting of mercurous chloride, mercury and potassium chloride solution of an appropriate concentration. Above the paste the vessel is filled with a potassium chloride solution saturated with mercurous chloride. According to the concentration of the potassium chloride solution (0,1 N — KOI, 1 A — KC1 or saturated solution of KC1) the decinormal, normal or saturated calomel electrodes are distinguished. 

An increase in the selectivity and sensitivity of the detection of carbonyl compounds may be achieved by their conversion into special derivatives. Johnson and Hammond [58] condensed carbonyl compounds with 2,4,6-trichlorophenylhydrazine and, prior to the analysis, separated the products by means of thin-layer chromatography. Using an ECD, they were able to determine by GC 10-7—10-10 g of the substance. They prepared the derivatives in a reaction column as follows. A 0.40-g amount of 2,4,6-trichlorophenylhydrazine was dissolved in 40 ml of 1 N HC1 with heating and mixed with 40 g of Celite 545. w-Hexane was added to the wet mixture until a paste consistency was obtained, and the column (30 X 2 cm I.D.) was filled with the paste. In order to prepare the derivatives, the carbonyl compound was applied to the column in an amount corresponding to half of the theoretical column capacity and the column was eluted with 75-100 ml of -hexane. The n-hexane was distilled off at decreased pressure and the viscous derivatives were stored in 10 ml of w-hexane at —27°C. However, these derivatives are sometimes not separated satisfactorily on silicone phases. 

Pencils, medicated Cylinders used in dermatologic practice to apply medicinal agents directly to the skin. The medicinal agent is incorporated into a paste consisting of starch, dextrin, tragacanth, and sucrose... 

Ribbon blenders typically have multiple helical ribbons with opposing pitches operating in a horizontal trough with a half-cylinder bottom. These mixers can be used for wetting or coating a powder. The final product may have a paste consistency but must remain at least partially flowable for removal from the blender. 

The General Electric SPE (17) consists of two porous particulate electrodes which are bondecTcohesively with polytetrafluoro-ethylene dispersion particles and connected electrically to the outside of the cell hardware by means of metallic current collectors which are pressed against the SPE by mechanical methods. Such an SPE can be prepared via perfluoroionomer solution techniques. One method is to apply a paste consisting of the electrolyte powder and the perfluoroionomer solution to the membrane and evaporate the solvent. Alternately, the paste can be applied to a sacrificial substrate such as aluminum foil, dried, and subsequently pressed into the membrane as a decal. 

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