F. Esposito et al., A GENERALIZED FORM OF THE LANGMUIR ISOTHERM FOR GAS-ADSORPTION IN GLASSY-POLYMERS, Industrial & engineering chemistry research, 35(9), 1996, pp. 2939-2945
Glassy polymers contain sites where excess free volume makes adsorptio
n of gases possible; they also contain sites where ordinary absorption
governed by Henry's law can occur. In this paper, we analyze the poss
ibility of a continuous distribution of site types, characterized by v
alues of adsorption capacity, affinity constant, and sorption constant
which span a continuous range. Experimental data are easily fitted wi
th great accuracy by the resulting equations; indeed, different sets o
f parameter values may fit any given set of data equally well, indicat
ing that evaluation of parameter values from experiments should be reg
arded with careful skepticism.