Accession Number : AD0608585

Title :   TRACER METHOD OF MEASURING LOW WATERVAPOR PERMEABILITY,

Corporate Author : HARRY DIAMOND LABS WASHINGTON D C

Personal Author(s) : NELSON,E. R. ; Shellenbarger,R. M. ; Besold,A.

Report Date : 01 OCT 1964

Pagination or Media Count : 43

Abstract : A rapid method for the measurement of rates of permeation of water vapor through polymeric films of very low permeability was studied. It was based on the reaction of C-14-labeled barium carbide with water to give barium hydroxide and radioactive acetylene. A sweep-gas apparatus, which incorporated a Geiger tube for counting the acetylene, was built and measurements were taken under steady-state conditions. This method proved to be rapid but neither absolute nor precise. While corrections might be applied to yield absolute values, none of the modifications that were attempted seemed to improve the reproducibility. Methods based on counting radioactive acetylene have been discontinued in favor of a method based on detecting simple unlabeled, hydrocarbons, e.g., acetylene, with an argon detector. (Author)

Descriptors :   (*PLASTICS, PERMEABILITY), (*TRACER STUDIES, PERMEABILITY), FILMS, POROSITY, WATER VAPOR, LABELED SUBSTANCES, CARBON, ALIPHATIC COMPOUNDS, COUNTING METHODS, GEIGER COUNTERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE