Estimation of permeation rate of chemicals through elastometric materials

Abstract

Elastometric materials are used as barriers to protect workers against exposure to chemicals. The effectiveness of a polymer as a chemical protective material therefore depends on the rate of the permeation of chemicals through it. The permeation rate depends on the solubility and the diffusion coefficient of chemicals in the materials. The diffusion coefficient itself is a strong function of concentration of the chemicals in the polymeric material. Permeation rates can be measured directly using a permeation cell or they can be calculated from the solubility and the diffusion coefficient data. Sorption/desorption experiments can be used to determine solubility and an expression for the diffusion coefficient in terms of concentration. Experiments were conducted for the sorption and desorption of ethyl acetate in three glove (one butyl and two neoprene materials) and two garment (neoprene and chlorinated polyethylene) materials. The data collected were used to estimate the steady-state permeation rates of ethyl acetate through the materials. The results of the experiments show that the solubility of ethyl acetate in butyl rubber is 0.795 g/cm3, and the steady-state permeation rate is 0.32 μg cm−2 s−1. The solubility of the chemical through the three neoprene materials is in the range of 2.25–5.31 g/cm3, and the steady-state permeation rates vary from 27 to 43 μg cm−2 s−1. The solubility of ethyl acetate in the chlorinated polyethylene is 7.14 g/cm3, and the steady-state permeation rate is 62.43 μg cm−2 s−1. The experimental method is very simple to use and it requires a small sample of the material (less than 1 cm2) and only a few milliliters of the chemical. Sorption/desorption experiments can also provide information on the amount of additives extracted from an elastomeric material during contact with a chemical. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1265–1272, 2001