Waterproof textiles have wide applications in many fields such as sportswear, protective clothing, and orthopedic dressing. Breathability is an important factor of clothing comfort. Nanofibrous layers have application in these fields due to their interconnected porous area and high surface area. In this work, two different nanofiber layers were fabricated and examined as waterproof and breathable layers. Polyurethane (PU) and PU/nylon 66 (hybrid) nanofiber layers were produced via electrospinning set up with different electrospinning durations. Some of the samples' characteristics such as tensile strength, microindentation, air permeability, water vapor permeability (WVP), and contact angle of water were investigated. Moreover, a novel approach was applied for determining the performance of layers against acidic water to simulate acidic rain. The results show that the tensile strength, indentation force, and acidic waterproof ability of the layers increased with increasing the process duration, that is, while air permeability was decreased simultaneously. This work shows that the required force for indentation and strength of the hybrid layer was less than that of PU nanofiber layer. Also, the electrospun hybrid layers show better air permeability than the PU membrane but still have lower WVP, which affects the breathability of the layer. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2016, , 21568; View this article online at wileyonlinelibrary.com.

To develop waterproof breathable membranes, a Janus lyophobic/lyophilic media composed of a poly(vinylidene fluoride) electrospun membrane and a hydrogel electrospun mat was proposed. Poly(vinylidene fluoride) membranes were electrospun in different electrospinning conditions to evaluate the effect of the fiber diameter on the membrane characteristics. Afterward, a layer of hydrogel was electrospun on the poly(vinylidene fluoride) electrospun mat. The hydrogel was synthesized through the esterification reaction of poly(vinyl alcohol) and poly(acrylic acid). This hybrid membrane can transfer the body-generated moisture to the environment while it prevents the penetration of liquid water from the reverse side. The proposed hybrid membrane represented improved water vapor permeability compared with the neat poly(vinylidene fluoride) membrane (from 12.6 kg/m2/day for the neat poly(vinylidene fluoride) up to 13.6 kg/m2/day for the hybrid) along with good water resistance (up to 70 kPa) and good windproof property (1 ml/cm2/s in pressure drop of 500 Pa). The results indicated that molecular diffusion is the main mechanism of moisture transfer in the poly(vinylidene fluoride) membranes with the fiber diameter ranging from 132 to 1136 nm. It has been found that the experimental effective diffusion coefficient ( Dexp) of the neat hydrogel layer (8.7 × 10−6m2/s) is much higher than the neat poly(vinylidene fluoride) membrane (approximately 4 × 10−6m2/s), signifying that apart from molecular and Knudsen diffusions, the surface diffusion has played a major active role contributing to much higher value of water vapor permeability in case of the hydrogel layer and subsequently in hybrid layers.

No abstract

No abstract

No abstract