Water Vapor Transmission Process

Narcote's laminate is a non-microporous polyetherester film bonded by a polyurethane adhesive to various fabrics in a finely dispersed dot pattern to allow for better vapor transmission or breathability.

The principle of water vapor transmission from our hydrophilic membrane works like this. The most important atmospheric parameters are water vapor concentration and temperature. The physical process of vapor transmission is accomplished by absorption, diffusion and desorption Vapor enters the membrane and is transported along molecular chains of this block copolymer to reach equilibrium with the the outside atmosphere, sometimes referred to as reverse osmosis.

The higher the differential from each side of the laminate the greater water vapor transmission ratio (gms/m²/24 hrs.). Exact measurements must be made under controlled conditions as ASTM E96 B. The membrane is waterproof and air tight, allowing only vapor transmission due to the differentials previously outlined.