Liquid penetration of barrier materials

Liquid penetration of porous materials is important for applications such as protective clothing, resin impregnation of fibers for composites, and filtration. A test apparatus for determining pressure at liquid breakthrough as a function of flow rate has been designed and constructed. Using this method, it was determined that liquid penetration of a material produces an interesting pressure curve where liquid breakthrough is followed by a peak in pressure and then a drop corresponding to equilibrium flow. This test method allows for comparison of materials in terms of barrier performance and also gives insight into the liquid saturation process.; Three materials were tested with water as challenge liquids of varying viscosity and wettability. It was determined that pressure at liquid breakthrough was not dependent on the flow rate nor the viscosity of the challenge liquid but was dependent on the wettability of the challenge liquid. Also of interest was that more passages were opened through the material as flow rate was increased.; A numerical model of liquid penetration of a barrier material was created based on invasion percolation. The model has been shown to be consistent with experimental results.