31.4 What is Goretex?
Description
This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.
31.4 What is Goretex?
Goretex is a dispersion-polymerised PTFE that is patented by W.L.Gore and
Associates [5]. It is classed as a stretched semi-crystalline film, and is
produced by extrusion under stress ( faster take-up rate than extrusion
rate ). The extrudate is stretched below the melting temperature, often
in the presence of an aromatic hydrocarbon that swells the amorphous region,
creating porosity. The hydrophobic nature of the PTFE means that liquid
water is repelled from the pores, whereas water vapour can pass through.
It is important to realise that once the PTFE pores are filled with liquid
water, the fabric can allow liquid water to pass though until it is dry
again. Thus Goretex-containing fabrics ( such as Nomex/Goretex - which
consists of an outer aramid fabric, a central Goretex layer, and a cotton
backing ) should never be used as protection from chemicals as many will
pass straight through. Any water-miscible solvent ( eg alcohol ) can fill
the pores, and then liquid water can displace it and continue to rapidly
pass through until the fabric is fully dried out.
Continue to:
My Books
