Abstract:

Abstract
The paper presents the results of tests on the structure, basic functional properties and physiological comfort of microporous polyurethane membranes designed for internal barrier layers of textile-polymeric composite systems with various characteristics and practical applications. The membranes tested were prepared at the Institute of Textile Materials Engineering according to the optimised manufacturing technology which we have developed. The tests performed have shown that, depending on the process conditions used, these membranes are characterised by a low thickness of about 50 μm, a very low rigidity and a surface weight of about 40 g/m2. Such membranes show a high overall porosity, while in addition to the through-micropores passing through the whole membrane thickness, numerous semi-closed pores are found. The uniformity of micropore distribution on the membranes’ surface and their different characters are confirmed by means of SEM photographs. The membranes also show a high water-tightness of about 250 cm column of water, practical wind-tightness and a high permeability of water vapour at the same time, under static conditions amounting to about 2000 g/m2 per 24 h (by the gravimetric method), as well as a low resistance of water vapour flow under dynamic conditions, at a level of 5-8 m2 Pa/W. A probable mechanism of the water vapour’s penetration through the membranes has also been established. Examination of the membranes with a DSC dynamic calorimeter has shown their stability within the range of both elevated and lowered temperatures, and consequently their high suitability for multi-layer composite materials designed for protective clothing used under various climatic conditions which satisfy the requirements of the current European standards.