CONCEPT AND MODEL OF MESOSCOPIC POROSITY FOR THIN PERMEABLE MEDIA

There are two main obstacles to perform the objective comparison and choice of preferable variant within the set of ap-propriate textile materials (TM), related to the thin permeable media: 1) the different experimental methodologies and tools usable by different authors for an estimate of water-vapor-transmission rate; 2) the different ambient conditions of such measurements and a variety of experimental means proposed, at present, for an estimate of TM-porosity. Recently we have studied, in detail, the former factor [V.B. Rogankov et al, Refrigeration Engineering and Technology, 51(1), 2015, pp.47-54] and pointed out the possible strategy to overcome this obstacle. In this work we will pay the main atten-tion to the latter factor. The novel concept of mesoscopic (nano-) porosity of threads is formulated for any woven and non-woven TMS. The resulting alternate basic (AB-) model for theoretical estimate of effective (observable) porosity in hydrophilic and hydrophobic permeable media is developed. It is based, exclusively, on the standard (but the measuring-laboratory-condition’s-dependent) measurements of so-called square mass and thickness for the wide set of 41 samples taken from 5 different experimental works. The proposed treatment of such data leads to the simple, well-founded rela-tionships of AB-model without any adjustable coefficients. They provide a possibility to obtain the reliable estimates for the following fundamental TM-characteristics: density of moist and/or dry matrix; observable effective porosity at any level of ambient moisture; maximum hygroscopicity without the additional experiments.