Study of water vapor permeability of shape memory polyurethane nanofibrous nonwovens

In this paper, water vapor permeability (WVP) properties of shape memory polyurethane (SMPU) nanofibrous nonwovens are investigated systematically. The results indicate that, in addition to the excellent shape memory effect, the SMPU nanofibrous nonwovens show excellent liquid transfer properties and water vapor transport properties. Moreover, the WVP of a SMPU nanofibrous nonwoven is sensitive to the change of relative humidity (RH) and temperature. For example, the WVP decreases with the increase of RH above a critical RH, e.g. 50%, and increases significantly with the increase of temperature below a turnover temperature, e.g. 50°C. The diameter of the nanofiber has little influence on the WVP while the turnover temperature is higher in SMPU nanofibrous nonwovens with larger diameters. Finally, SEM images at a higher temperature suggest that the porous nanofibrous nonwoven structure is the foundation of unique WVP properties, and the collapse of the nanofiber at the higher temperature results in the abrupt decrease in WVP.