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Title: Solution and diffusion of some gases in polymer laminates
Author: Palmer, David Gordon
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1966
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By a development of the method of Frisch expressions have been obtained for the time lags measured at both boundaries of a membrane under conditions of sorption, desorption and flow reversal. The treatment relates to flow of heat or matter in slabs, hollow cylinders and spherical shells under conditions where the diffusion coefficient is independent of concentration, positional coordinate and time, and where solution of the diffusant is governed by Henry's law. Expressions for similar time lags have been obtained for a multiple laminate comprising n such laminae (each being made of a different material) in terms of the normal time lags associated with the individual laminae. Relationships between the time-lag differences and the quantity of diffusant in the membrane in the steady state have been obtained from both diffusion theory and a simple conservation principle, resulting in a suggested means of obtaining isotherms from flow measurements alone, even when the dependence of the diffusion coefficient upon concentration, positional coordinate and time is unknown. Using permanent gases measurements were made at a number of temperatures of the normal time lag on a laminated hollow cylinder comprising two sheaths, the inner being nylon 11 and the outer polyethylene. The values obtained agreed well with those calculated from the time lags measured on the individual sheaths. Desorption time lags measured at the outgoing boundary on the individual sheaths were in good agreement with the values predicted by theory. Using apparatus based on Meares, static solubilities have been measured on the individual sheaths The values obtained for nylon were in good agreement with the dynamic solubilities • obtained from permeation experiments, but for polyethylene the static solubilities were approximately 25% larger than the dynamic values. Possible reasons for this difference have been discussed. The design of a cell is suggested which permits both permeation and static solubility experiments to be made alternately on the same sample
Supervisor: Barrer, R. M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available