Outgassing time/temperature

There is some evidence that the heat of immersion of the well outgassed samples was liberated during a rather long time. Consequently, the heats of immersion of these samples, and also of some of the samples with small amounts of water adsorbed, were determined by integration of the recorded time-temperature curve from the time the samples were wetted until the temperature of the calorimeter had returned to its steady state. Sixteen hours were required in the case of the freshly outgassed samples instead of the 5 to 6 hours normally required. 

R. M. Barrer Outgassing times depend upon the openness of the crystals, the cations present, and the size of the crystals. As a practical working rule for water removal, a final temperature of not less than 360°C maintained under the best vacuum for not less than 24 hours is desirable. 

Test personnel are faced daily with a decision about how long (or how well) a test dewar should be pumped. As we discussed earlier, adequate vacuum practice for long-life sealed dewars has been studied thoroughly, and many tools are available to assist in vacuum decisions and predictions residual gas analysis, outgassing rates, vacuum bake, time-temperature schedules, and so on. 

At constant temperature, the time-dependence of outgassing follows the relationship ... 

Fig. 26. IR time-resolved spectra of ethene polymerization reaction on (a) nearly stoichiometric and (b) reduced a-Cr2C>3 samples CH3 and CH2 stretching mode regions. Continuous curves, IR spectra taken at 10-s intervals (a) and 7-s intervals (b) in the presence of P = 5.32 kPa of ethene dashed curves after a total contact time of 30 (a) and 8 min (b) and ethene removal by outgassing at room temperature curves on the bottom, ethene gas [reprinted with permission from Scarano etal. (493), Copyright 1994 American Chemical Society].

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