Followed by controlled cooling (quenching) or coagulation. 1 The membrane is produced from a mixture of components which is extruded or cast to form a membrane. Microporous membrane was made from poly(phenylene sulfide) containing plasticizer. MARINA, in Handbook of Plasticizers (Third Edition), 2017 11.44 POLY(PHENYLENE SULFIDE) Generally, the membrane is ‘dot’ laminated (for example hot melt screen printing using polyurethane adhesive dots) to the outer fabric and frequently also to an inner, fairly open and flexible fabric which provides flexibility and facilitates the passage of perspiration to the outside, the membrane being sandwiched between the two ( Fig. The membrane can be laminated to a non-woven or tricot fabric. Drop liners are also used, where the breathable laminate is inside, but separate from, the outer fabric, and therefore in no way affects the handle, drape and constructional characteristics of the outer fabric. Two-layer laminated fabrics are popularly used for sportswear and fashion leisurewear, often with a loose lining or other insulation material. Such fabrics are popular for military wear, foul weather garments and work-wear. warp knitted) and an outer abrasion resistant fabric (e.g. Today, some of the most durable and high-quality breathable fabrics are produced by laminating (sandwiching) a micro-porous membrane between two fabrics: an inner, soft and flexible fabric (e.g. Micro-porous based breathable fabrics usually have a layer of hydrophilic polyurethane or water repellent finish (fluorocarbon or silicone) so as to ensure consistent performance and to prevent the pores being contaminated.
35 Micro-porous membranes typically weigh 10–20 g/m 2 and should be durable and resistant to laundering, chemicals and UV degradation. Micro-porous structures work, as do tightly woven structures, because of the large difference in size between individual water molecules present in water vapour and water droplets of rain, each of the latter consisting of many millions of water molecules held tightly together by surface tension forces.
Such holes (or pores) are too small to allow water droplets to pass through, but are large enough to allow water vapour to pass through.
35 Sheets of polymers can be produced with common salt incorporated which is washed out afterwards to leave voids/pores. Micro-porous coatings and membranes rely on an interconnected network of tiny holes (pores) introduced by various means into an otherwise impermeable polymeric structure. coated) or formed into a membrane and then laminated to the fabric.Ī micro-porous membrane (or coating) can be defined 34 as a thin-walled structure having an open spongy morphology of precisely controlled pore size, typically ranging from 0.03 μm to 10 μm in diameter. In most cases they can be cast directly onto the fabric (i.e. Micro-porous membranes are generally made from the polymers 27 PTFE, polyurethane (PU), polyolefins, polyamides, polyester, polyether and polyether based copolymers, with the first two mentioned (i.e. Fan, in Engineering Apparel Fabrics and Garments, 2009 Micro-porous membranes and coatings
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