ISSN:
0022-3832
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Equilibrium and kinetic studies of the sorption and desorption of water vapor by poly(acrylic acid), poly(sodium acrylate), sodium carboxy methyl cellulose, methyl cellulose, and a series of poly(methyl acrylate) hydrolyzates in acid and sodium salt forms were made at 30°C. It was found, as expected, that equilibrium sorption increased and was greater for polymers containing strong-electrolyte type substituents than for those containing an equivalent number of weakly ionizable units. In general, the diffusion is somewhat slower than in the case of water-insoluble polymers. It was also found that water solubility of a polymer does not per se result in anomalous water sorption. In Methocel, for example, water diffusion is both Fickian and concentration-independent. All of the results, particularly those on the poly(methyl acrylate) hydrolyzates which ranged from completely water-soluble to insoluble systems, support the following conclusion: For water-soluble polymers both anomalous diffusion and relatively high glass temperatures are associated with high concentrations along polymer chains of very polar or ionic groups, such as —OH, —COOH, and CO2-Na+. Presumably both the anomalies and high transition temperatures are associated with restricted segmental mobility resulting from strong chain-chain interactions which originate in the highly polar and ionic, water-solubilizing chain substituents.
Zusätzliches Material:
8 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1956.1202210219
Permalink
