AbstractOxygen permeability data on heterogeneous films prepared from mixtures of different polymer latices were compared with predictions of a permeability theory of Higuchi based on an idealized barrier model. The theory attempts to evaluate the effect of perturbations of the diffusion process associated with the presence of a discontinuous internal‐phase component. An approximate form of the theoretical permeability expression was found to render reliable predictions of the effective permeability of heterogeneous barrier systems. When the partition of the permeant between different phases of the barrier is sufficiently rapid, the theory becomes applicable to the early, nonsteadystate, stage of permeation. Implications of the general applicability of the Higuchi theory to heterogeneous systems are discussed with respect to the interaction between the constitutents and the associated departures from the ideal behavior assumed for the mode
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