Contaminant Diffusion through a Novel Coextruded Vapor Barrier: Fid-Bau Portal

Contaminant Diffusion through a Novel Coextruded Vapor Barrier

DiBattista, V. / Rowe, R. Kerry

Organic contaminant diffusion through a novel multilayer coextruded vapor barrier is examined for benzene, toluene, ethylbenzene, xylenes (BTEX), trichloroethylene (TCE), and tetrachloroethylene (PCE). The vapor barrier considered is composed of five materials: linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ethylene vinyl alcohol (EVOH), a tie layer (TL), and a degradation layer (DL). Parameters for the LLDPE, HDPE, TL, and DL are developed using material-specific diffusion tests. Contaminant-specific permeation coefficients ( $P_{g}$ ) for these materials range from 1.4 to $9.2 \times 10^{- 11} m^{2} / s$ . The diffusion parameters of the EVOH are inferred from testing of a thin (0.0889-mm) coextruded LLDPE/TL/EVOH/TL/EVOH membrane, and the contaminant specific $P_{g}$ values range from 1.9 to $7.0 \times 10^{- 14} m^{2} / s$ . These individual layer parameters are used to develop a single set of parameters for each contaminant for the entire vapor barrier, with overall contaminant specific $P_{g}$ values of $2.7 - 13.8 \times 10^{- 13} m^{2} / s$ . The parameters are used to model various vapor intrusion scenarios which show that the multilayer vapor barrier results in significant predicted decreases in airspace concentrations compared to HDPE or no barrier.