The Influence of Temperature upon Permeability

The influence of temperature upon permeability The velocity of diffusion through a metal increases very rapidly as the temperature rises, as Pig. 50 illustrates for 

However, some of the earliest studies of permeation velocities expressed these velocities as 

For example, Winkelmann (8) gave for the passage of hydrogen through iron while Johnson and Larose(o6) for the 

From the slopes of the curves logP against IjT, one may calculate the temperature coefficient in cal./atom of gas transferred. The first attempt to give a meaning to this temperature coefficient is due to Richardson, Nicol and Parnell (9), and no subsequent theories have improved greatly 

In this field some very thorough studies have been made for hydrogen-metal systems, especially by Lombard and Eichner(69), Smithells and Ransley (60) and Post and Ham(6i). Even for hydrogen-metal systems, however, the interpretation of the permeation rate-pressure isotherms is not clear. Studies of glass, crystal, and organic membrane permeability have shown that two possible permeation rate-pressure relationships emerge  

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The data of previous sections indicates that at low humidities one may use the linear Fick law as an approximation which breaks down as the humidity increases. The influence of temperature upon permeability constants is two-fold. There is first the effect upon the diffusion constant and secondly the effect upon the absorption coefficient, k. Sometimes in colloidal systems the coefficient k increases with temperature even when... 

Table 113. The influence of temperature upon permeability constants for water diffusion (9)...

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