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Gel–water relationships in hydrophilic polymers: Thermodynamics of sorption of water vapor
Author(s) -
Masuzawa Mitsunobu,
Sterling Clarence
Publication year - 1968
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1968.070120904
Subject(s) - sorption , water vapor , adsorption , carboxymethyl cellulose , polymer , crystallinity , thermodynamics , monolayer , monomer , steric effects , gelatin , chemistry , chemical engineering , materials science , polymer chemistry , organic chemistry , crystallography , engineering , sodium , biochemistry , physics
A thermodynamic study was conducted of water vapor adsorption on four hydrophilic polymers (agar, carboxymethyl cellulose, gelatin, and maize starch) at 12 and 25°C. Monolayer coverage amounted, after correction for crystallinity, respectively, to 0.93, 1.46, 0.51, and 0.77 mol water/mol monomer. Evidence is adduced from the Bradley equation and thermodynamic data to indicate that at least during coverage with the second layer of water, the energy of adsorption is greater than that due to condensation alone. Differences in the amount of sorption and in the trend of values of ΔS̄° and ΔH̄° with the amount of sorbed water are related with differences in the strength of intermolecular association as affected by steric hindrances.