Scanning studies on capillary condensation and evaporation of nitrogen. Part 1.—Apparatus and calculation method
Abstract
For collection of extensive sets of data on scanning behaviour within nitrogen sorption hysteresis-loops at 77.6 K, an apparatus has been described by which a preprogrammed sequence of adsorption–desorption cycles within the hysteresis region can be recorded fully automatically. This has enabled the determination of up to 3000 datum points distributed over some 60 primary scanning curves, in a single run, without interruption of the measurement. Subsequently, a method has been described for obtaining quantitative information on capillary evaporation and condensation phenomena from scanning data. It has been shown that the slope and intercept of the tangent lines to a set of primary scanning curves at the point of pressure reversal can be directly related to the actual porous structure. This leads to a new independent method for determining pore size distributions.