Accession Number : AD0713731

Title :   THE PROPERTIES OF WATER IN CAPILLARY SYSTEMS.

Descriptive Note : Technical rept.,

Corporate Author : HYDRONAUTICS INC LAUREL MD

Personal Author(s) : Frommer,Moshe A. ; Shporer,Mordechai ; Loebel,Esther ; Bloch,Rene

Report Date : SEP 1970

Pagination or Media Count : 38

Abstract : The properties of water adsorbed on various membranes prepared from cellulose acetate (C.A.) and from cellulose triacetate (C.T.A.) were investigated. Adsorption isotherms, nmr spectra and preliminary longitudinal and transversal nmr relaxation times (T(1) and T(2)) of the water in the membranes were determined. It was found: (1) The amounts of water sorbed in C.A. membranes at relative humidities lower than 0.6 depend primarily on the weight of the polymer and are practically insensitive to its structure (powder, extruded film, or cast membrane). (2) The amounts of water adsorbed in C.A. membranes at relative humidities higher than 0.7 are primarily determined by the porosity of the substrate. (3) Due to magnetic susceptibility, the position of the proton resonance peak of water in sheet membranes depends on the geometry of the sample with respect to the external magnetic field. This geometrical effect can be avoided by crushing the sheet membrane into fine platelets. (4) Both T(1) and T(2) of water in C.A. and in C.T.A. membranes increase with the amount of water in the membrane. (5) Even though the water molecules seem to be highly mobilized, the fact that T(1) > T(2) indicates a surface effect on the water. (Author)

Descriptors :   (*CELLULOSE ACETATES, *MEMBRANES), (*WATER, *ADSORPTION), NUCLEAR MAGNETIC RESONANCE, RELAXATION TIME, POLYMERS, SURFACE PROPERTIES, MAGNETIC PROPERTIES

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE