Polypropylene, garments

Nielsen and Edrusick [29] evaluated the effect of five kinds of knit structures, all made from 100% polypropylene were evaluated. On subjects exercising for 40 minutes at 5°C followed by 20 minutes at rest, and then repeated. The thickest knit, a fleece, caused the greatest total sweat production, retained the most moisture, and wetted skin the most. They stated that the hydrophobic polypropylene prevented extensive sweat accumulation in the underwear (10 to22%) causing the sweat to accumulate in the outer garments. 

Bakkevig and Nielsen [35] repeated the protocol above, but used low and high work rates with three kinds of underwear (a polypropylene lxl knit, a wool lxl knit, and a fishnet polypropylene) worn under wool fleece covered by polyester/cotton outer garments. Total sweat production and evaporated sweat were the same for all three underwear fabrics, but where the sweat accumulated differed significantly. More sweat accumulated in the wool underwear than either polypropylene at both work rates. At the higher work rate, more sweat moved into the fleece layer from both kinds of polypropylene underwear than for the wool. Most likely for the lxl knits, the thicker wool underwear(1.95 mm) simply holds more water than the polypropylene underwear (1.41 mm) and based on outer layer-to layer wieking results, needs a greater volume of sweat to fill it pores before it starts to donate the excess to the layer above it. 

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