Preliminary comparison of contact angle and wetting resistance of water-repellent treated cotton woven fabric

Abstract

Filtration capability of textile media or the resistance towards the fluid penetration through different fabrics is depending on their surface repellence. The emission of condensed exhaled air on the outer layer of the half facemask from the FFP2 (EN 149) category indicates the termination of its protective properties. The overcoming by the fluid of the textile environment of the mask in its role of an artificial barrier goes through two stages. Initially, the aerosols in the exhaled air condense and meet the repulsion from the inner fabric. Later, due to the hydrodynamic pressure, the condensed droplets pass through the textile medium, overcoming the friction among the fibrous layers. Finally, the droplets irrigate the outer, front layer of the mask and are released into the environment with all the consequences. Closest to this physiological process is the hydrostatic pressure test method. The test of resistance to fluid penetration gives a final assessment of the property of the textile environment without clarifying the elements of the process. Experimental studies have shown similarities in the results of the penetration of the fluid through the textile medium and the initial repulsion of aerosols from the surface of the fibrous layer. The repulsion of water droplets is of predominant importance in relation to the general barrier capacity of the textile media. The main indicator of water repellence is the contact angle of the free drop on the fabric. The subject of this article is the comparison between the contact angle of wetting and the penetration of the fluid by means of standard test methods. The aim of the work is to explain and model the process of fluid penetration through protective masks, as well as to optimize the properties of repulsion and resistance.