Chemical protective clothing: Permeation behavior of chemical binary mixtures

An investigation into the permeation behavior of four selected binary mixture/material challenge series was conducted. The hypothesis examined was based on the existing knowledge that neat compounds which possess high permeation rates and short breakthrough times, also tend to swell the material. A binary mixture containing both a high and a low permeation rate component might sustain a permeation pattern where the low permeation rate component (B) is actually diffusing through the high permeation rate component (A), rather than through the material itself at steady-state. This was examined using immersion and permeation experiments. Five challenge concentrations, consisting of both neat components, 25-75, 50-50, and 75-25 volume per cent binary mixtures, were employed for all experiments. Immersion experiments, used to determine mass and volume changes of fully immersed material specimens, were performed using two test durations. The first was 24-hours with measurements at 1, 4, 8, 12, and 24-hour(s). The second was 2-hours with measurements every 10 minutes. All permeation experiments employed the standard ASTM permeation cell. The permeation apparatus was an open-loop system where a continous flow of fresh collecting medium (filtered dry air) carried the permeant(s) from the collection side of the test cell to the analyzer. All chemical analyses were conducted using a quadrupole gas analyzer. All experiments were conducted in triplicate and permeation experiments were carried out until steady-state permeation was achieved or 24-hours had elapsed. 43 refs., 19 figs., 4 tabs.