The theory that supports permeation testing indicates that contaminants will saturate a protective material given sufficient exposure. Once the challenge is removed, chemicals within the matrix diffuse out in both directions. The purpose of this study was to develop a method of measuring contamination of protective clothing materials and to investigate solutions to the problem of matrix contamination and release. Experimental procedures used provided the basis for the ASTM standard development in this area.
Experiments consisted of challenging neoprene, Viton, and butyl with nirobenzene. Percent contamination was measured as a percent by weight of the virgin material at several time intervals up to saturation. Up to 46% contamination was detected.
Three possible solutions to the problem of contamination were investigated: decontamination between wearings, materials with very long breakthrough times, and disposable protective clothing. Disposable protective clothing appears to be the most practical solution at the present time.
Decontamination using solvent flushing (Freon 113) was not effective even after two washes. The data generated also indicated that chemical exposure can alter the barrier properties of the material. Thermal decontamination proved effective with nitrobenzine and neoprene, but more research is needed to determine the extent to which it can be applied. Teflon-coated Nomex, which has a long breakthrough time, exhibited no detectable matrix contamination. As expected, contamination was found to be inversely related to breakthrough time. Where exposure times are very small fractions of breakthrough time, it may be possible to decontaminate by surface cleaning. Disposable protective clothing of laminated Tyvek offers excellent barrier properties to many chemicals. With disposable clothing worn by itself or over a reusable clothing, the contamination problem is discarded with the contaminated garment.