Physical Properties of Polyurethane Blend Dope-Coated Fabrics

Abstract

We investigate the effects of the cross-sectional structure of a polyester-type polyurethane (pu)/polyvinylchloride (pvc) blend dope-coated nylon fabric on moisture permeability. The waterproof coating is applied by a one-sided wet-coagulation process. The blending of hydrophobic pvc to hydrophilic pu forms a three-layered cross-sectional structure—a pvc-rich micronetwork, a porous pu-rich layer, and the nylon fabric. As the blend ratio of pvc to pu increases, the moisture permeability (mp) and dew condensation (dc) of the coated fabrics improve. Compared to the pu homopolymer, the mp value of a pu/pvc blend in a weight ratio of 4:1 increases 1.18 times to 492 g/m2·h (JIS A-1 method) and 1.16 times to 815 g/m2·h (JIS B-1 method), but the dc value decreases one-fourth to 4.60 g/m2 · h. This gradient three-layered cross-sectional structure contributes to vapor transport properties.