Accession Number : ADA304743

Title :   Three Methods for In Situ Cross-Linking of Polyvinyl Alcohol Films for Application as Ion-Conducting Membranes in Potassium Hydroxide Electrolyte.

Descriptive Note : Technical paper,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Philipp, Warren H. ; Hsu, Li-Chen

PDF Url : ADA304743

Report Date : APR 1979

Pagination or Media Count : 18

Abstract : Three methods for in situ cross-linking of water soluble polyvinyl alcohol films are presented. These cross-linked films show promise for use as battery separators in aqueous potassium hydroxide (KOH) electrolyte. Electrical resistivities in KOH of cross-linked membranes representing the three procedures are given with a brief discussion of the chemical mechanism involved in their preparation. Physical properties, such as mechanical strength and swelling in alkaline electrolyte, are discussed. The three cross-linking techniques entail: (1) Treating a polyvinyl alcohol membrane containing a specified amount of a dialdehyde such as glutaraldehyde with an acid solution which catalyzes acetalization cross-linking. (2) Treating a polyvinyl alcohol film with periodic acid which cleaves the few 1, 2 diol units present in polyvinyl alcohol with the formation of aldehyde groups which then causes cross-linking via acetalation of the 1, 3 diol units. (3) Reacting a polyvinyl alcohol film with hydrogen atoms and hydroxyl radicals from irradiated water whereby cross-linking is accomplished by polymer radicals formed as a consequence of hydrogen abstraction. Hydrogen abstraction cross-linking of films containing both polyvinyl alcohol and polyacrylic acid in polymer solution improves strength in 45 percent KOH. Films made from solely polyacrylic acid were unsatisfactory. jg p3

Descriptors :   *IONS, *CONDUCTIVITY, *CROSSLINKING(CHEMISTRY), *MEMBRANES, *HYDROXIDES, *POTASSIUM COMPOUNDS, *POLYVINYL ALCOHOL, SOLUTIONS(MIXTURES), CHEMICALS, PHYSICAL PROPERTIES, WATER, POLYMERS, FILMS, ATOMS, STRENGTH(MECHANICS), HYDROGEN, ELECTRICAL RESISTANCE, IRRADIATION, ELECTROLYTES, HYDROXYL RADICALS, ALDEHYDES, ALKALINITY, CHEMICAL RADICALS, ACRYLIC ACID, BATTERY SEPARATORS.

Subject Categories : Polymer Chemistry
      Physical Chemistry
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE