Diffusion of water through various polymer films: a new high performance method of characterization

Abstract Diffusion of water in polymer films has been characterized by using a new high performance and reproducible method based on permeation measurements. With this method, which uses a fast response water-specific sensor based on dew point measurement, it is possible to determine, from the transient step, the time lag water diffusion coefficient D L and, when the steady state is reached, a mean water permeability coefficient P . In this work we have emphasized the water concentration dependence of diffusion coefficient D . After calibration, the technique yields accurate values of P , consistent with literature data. By testing various polymers, different behaviours with respect to water have been observed, particularly with low density polyethylene (LDPE) which shows significant hydrophobic properties.