The Effect of Absorbed Water on the Properties of Cotton and Fibers from Hydrophilic Polyester Block Copolymers

Abstract

This paper describes the effect of water on the fiber properties and the moisture-retaining ability of cotton in relation to hydrophilic model block copolymer fibers. These model fibers were made from hydrophohic polyethylene terephthalate segments and hydrophilic polyethylene oxide segments. Drawn, heat-set fibers having up to 20% of water-soluble seg ments with molecular weights of 4000, up to 5% with molecular weights of 20,000, and with many intermittent percentages and molecular weights, gave suitable model fibers with DTA melting points ranging from 240 to 259°C. Increased moisture sorption affects these fibers as it affects cotton or rayon. It causes fiber swelling, reduced dry and wet glass transitions, and reduced wet and/or hot/wet recovery properties. The moisture reservoir within the fiber struc tures poses another product liability, because all hydrophilic fibers have slower drying rates than hydrophobic man-made fibers. Under hot/humid conditions this propensity causes prolonged wet clinging of garments to the body and requires higher energy use for drying of garments in home or commercial dryers.