PHYSICAL-PROPERTIES OF POLYURETHANE BLEND DOPE-COATED FABRICS

We investigate the effects of the cross-sectional structure of a polye ster-type polyurethane (PU)/polyvinylchloride (PVC) blend dope-coated nylon fabric on moisture permeability. The waterproof coating is appli ed 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 (De) of the coated fabrics improve. Compare d to the pu homopolymer, the MP value of a PU/PVC blend in a weight ra tio of 4:1 increases 1.18 times to 492 g/m(2).h (JIS A-1 method) and 1 .16 times to 815 g/m(2).h (JIS B-l method), but the Dc value decreases one-fourth to 4.60 g/m(2).h. This gradient three-layered cross sectio nal structure contributes to vapor transport properties.