Air-trapping

The mold is usually prepared with orifices to permit air trapped between the sheet and the mold to escape and ensure uniform, close contact of the plastic with the mold surface. By clamping the sheet beyond the perimeter of the piece, plastic may be drawn from the peripheral areas into the mold, ensuring uniformity. Both pressure and vacuum are employed to force the softened plastic sheet into the mold. 

Di-tert-butyl peroxide (tert-butyl peroxide) [110-05-4] M 146.2, d 0.794, n 1.389. Washed with aqueous AgN03 to remove olefinic impurities, water and dried (MgS04). Freed from /cr/-butyl hydroperoxide by passage through an alumina column [Jackson et al. J Am Chem Soc 107 208 1985], and if necessary two high vacuum distns from room temp to a liquid-air trap [Offenbach and Tobolsky J Am Chem Soc 79 278 1957]. The necessary protection from EXPLOSION should be used. 

Luft,/. air atmosphere, -ablass, m. escape of air air outlet, -abscheider, m. air separator. deaerator, -abschluss, m. exclusion of air air trap, -abschreckung,/. (Metal.) air quenching, -abwehr, /. air defense, antiaircraft. -abzug. m. air exhaust, air exhaiister. 

Evaporation and condensation (a and b) osmosis (c and d). Water tends to move spontaneously from a region where its vapor pressure is high to a region where it is low. In a — b, movement of water molecules occurs through the air trapped under the bell jar. In c — d, water molecules move by osmosis through a semipermeable membrane. The driving force is the same in the two cases, although the mechanism differs. 

Liquid water, including its soluble and insoluble constituents, is transferred from the oceans to the atmosphere when air bubbles in the water rise to the surface. These bubbles form from air trapped by breaking waves, "whitecaps." As the bubbles burst at the surface, water droplets are injected into the atmosphere. These water droplets are small enough to remain airborne for several hours. Whitecaps begin to form in winds common over the oceans, and a significant amount of seasalt made airborne in this way is transported to the continents and deposited in coastal areas. 

The interstitial air trapped during this process preserves a largely unaltered record of the composition of past atmospheres on time scales as short as decades and as long as several hundred thousand years. Such records have provided critical information about past variations in carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), and the isotopic composition of some of these trace species. In addition, studies of the major elements of air nitrogen, oxygen, and argon, and their isotopic composition, have contributed... 

During chemical and physical transformations, any of the four variables in the ideal gas equation P, V, n, T) may change, and any of them may remain constant. The experiments carried out by Robert Boyle are a good example. Boyle worked with a fixed amount of air trapped in a glass tube, so the number of moles of gas remained the same during his experiments. In other words, n was held constant. Boyle also worked at only one temperature, so T remained constant. Example applies the ideal gas equation to this situation. 

The prepared flask is supported so that the tube B can be sealed to a vacuum system. If a suitable furnace is available the flask is surrounded by this, with the constriction A still within reach of the hand torch flame otherwise the heating must be done by flame. A liquid air trap is included between the flask and diffusion pump. With a vacuuih of below 10 mm of mercury the temperature of the flask is raised to near the softening point—the heating may be rapid... 

The Dewar seal is important and useful, although a ring seal can sometimes be substituted in simple apparatus—as, for example, in the cold finger liquid air trap shown in Figure 52, III. In the making... 

Fig. 5.1a shows the slurry packing system that 1 use. This operates at a fairly low pressure, as I am not especially interested in producing columns with very high efficiencies, but rather in saving on the cost of commercial columns. The pump and high pressure valve are rated for pressures of 500 bar (7500 psi) and 400 bar (6000 psi) respectively. The slurry reservoir is a stainless steel tube 85 cm long, with a capacity of about 50 cm3. The method is not hazardous unless there is air trapped in the high pressure line nevertheless it is advisable to use a safety screen. 

An open cylindrical dram, with a diameter of 2 ft and a length of 4 ft, is turned upside down in the atmosphere and then submerged in a liquid so that it floats partially submerged upside down, with air trapped inside. If the dram weighs 150 lbf, and it floats with 1 ft extending above the surface of the liquid, what is the density of the liquid How much additional weight must be added to the drum to make it sink to the point where it floats just level with the liquid ... 

A shallow depression on the otherwise smooth surface of a moulded product, generally due to air trapping. 

A compounding ingredient used to reduce the plasticity (increase the stiffness) of rubber compound and thus enable, e.g., an extruded section, to retain its shape or to reduce air trapping in moulding soft rubbers. 

A 2-1. three-necked round-bottomed flask is fitted with a reflux condenser and a glass inlet tube connected to a cylinder of nitrogen. The third opening of the flask is closed by a stopper. The top of the condenser is connected to an air trap which consists of two SOO-cc. suction flasks joined in series. The first suction flask is empty the second contains 100 cc. of paraffin oil, and the inlet tube of this flask extends slightly below the surface of the oil. 

Filling the vessel is an obvious necessity, but because of the fine pore structure of the GORE-TEX membrane (described below), air trapped in the vessel does not pass... 

Fill the burette with NaOH solution. To remove any air trapped in the tip, allow a small amount of the base to flow from the tip of the burette into the discard beaker. Read the burette to the nearest 0.02 mL and record this initial reading. The meniscus of the solution in the burette should be at eye level when you make a reading. 

High-resolution- Normal Inflammation of the Large holes in Air trapping... 

Iron concentrations as a function of depth in the Antarctic Vostok ice core, together with mean COq concentrations in air trapped in ice, versus mean age of air. Source From Martin, J. (1990). Paleoceanography 5, 1-13. 

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