Accession Number : ADA155605
Title : Permeation of Mixed Penetrants through Glassy Polymer Membranes.
Descriptive Note : Final rept. Feb 81-Jan 85,
Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH
Personal Author(s) : Chern,R T ; Hopfenberg,H B ; Stannett,V T
Report Date : 15 Mar 1985
Pagination or Media Count : 248
Abstract : This report summarizes the results of research activities supported by the Army Research Office. Three important areas were investigated: (1) Selective permeation of mixed gaseous penetrants in glassy polymers; (2) Transport of a reactive penetrant in polymers; and (3) Effects of chemical modification resulted from exposure to reactive penetrants on the permeability of the polymer to permanent gases. The results of the first study indicated that the penetrants in a gaseous mixture compete with each other for diffusion paths provided by the microvoid sorption sites existing typically in a glassy polymer when the polymer was vitrified. The permeability to a given penetrant in a mixture is depressed from its pure-component value simply due to the competition effect. In the second area, we found that polyimide, often quoted for its chemical stability, is susceptible to attack by a strong nucleophile, ammonia. Finally, through ESCA and permeability measurements, we demonstrated that high-temperature fluorination of polyethylene, which gives a relatively well defined surface fluorinated layer, is controlled by the diffusion rate of fluorine. On the other hand, room temperature fluorination tends to be reaction-controlled and results in a distribution of fluorine atoms throughout the thickness of the film.
Descriptors : *PERMEABILITY , *POLYMERS , *GASES , MEASUREMENT , THICKNESS , ARMY RESEARCH , DISTRIBUTION , CHEMICAL PROPERTIES , MODIFICATION , HIGH TEMPERATURE , FILMS , RATES , ATOMS , GLASS , ROOM TEMPERATURE , AMMONIA , MIXTURES , PENETRATION , FLUORINE , MEMBRANES , DIFFUSION , SORPTION , FLUORINATION , POLYETHYLENE , POLYIMIDE RESINS
Subject Categories : Polymer Chemistry
Distribution Statement : APPROVED FOR PUBLIC RELEASE