A diffusion model for water vapor transmission through microporous polyethylene/CaCo3 films

The stretching of mineral filled polymers can create an interconnected microporous structure due to debonding at the mineral/polymer interface. Such materials can allow for the transmission of gases (breathability) while retaining a liquid barrier. Stretched polyethylene/CaCO3 films that allow for water vapor diffusion while providing a barrier to liquid water are used for the current work. A model for the diffusion of water vapor through these films is demonstrated. This model assumes Fickian behavior. The significance of the model is that it relates the pore microstructure to breathability. Analysis of the pore structure by density and surface area measurements is combined with the results of the Fickian diffusion model to gain insights into the effects of pore geometry on breathability.