Study of the water and vapor permeability of membrane materials of different structures

The water and vapor permeability index is one of the determinants of the level of comfort of clothing materials. The paper presents the results of investigation of water and vapor permeability of waterproofing membrane materials when changing the difference of partial pressures of water and vapor from both sides of the tested sample. In order to realize the purpose of the research, the structure of the materials was examined by scanning electron microscopy and their water and vapor permeability was examined by the Taylor's method. It was shown that among the studied objects, membrane materials with a hydrophobic porous membrane change their vapor permeability when the pressure gradient changes according to a power or exponential law, depending on the type of the porous structure, while materials with a hydrophilic non - porous membrane change their vapor permeability according to the logarithmic law. On the basis of the conducted research it is recommended to use materials with a mesh membrane structure for manufacturing waterproof clothes for sports and recreation activites. In clothes made of materials containing a hydrophobic porous membrane of a sponge structure it is necessary to provide ventilation holes in addition. Materials with a monolithic hydrophilic membrane can be used for making windbreakers and raincoats that are used in cool rainy weather by low activity wearers.