Electrospinning of nanofibers : breathable, waterproof and protective advanced textiles -

Abstract

Electrospinning has been recognized as an efficient technique to produce polymeric nanofibers with diameter in the range of 100 nm to several microns. Considering electrospun webs’ outstanding properties (i.e., high surface area and high porosity), it can be used in many different applications (e.g., membranes, filters, advanced composites, wound dressing, and waterproof breathable fabrics). In this project, a large number of nanofibrous polyurethane (PU) webs were electrospun by changing different effective parameters (e.g., polymeric concentration, voltage, feed flow, etc.). The physical-chemical properties of the webs (i.e., fiber diameters, thickness, areal density, porosity, contact angle, waterproofness, air permeability, water vapor transmittance and aerosol filtration) were studied based on standard test methods. A commercially available waterproof breathable fabric (Tyvek PT31L0 from DuPont™) was used as a reference for benchmarking. The diameter of electrospun nanofibers at various conditions were in the range between 150 and 420 nm. The minimum fiber diameter of 150 nm was achieved from electrospinning of 10wt.percent PU in DMF, at feed rate of 500 µl-h, voltage of 25 000V, and tip to collector distance of 15 cm. The longer time of electrospinning increased the thickness and reduced the porosity of the webs. By optimization of the electrospinning parameters, we were able to make a web with high level of waterproofness, high air permeability, and high water vapor transmittance. In addition, the optimized electrospun web showed very promising aerosol filtration efficiency with complete removal of particles larger than 0.5 µm and reducing the concentration of smaller particles by 94percent. The results of this study show the possibility of using electrospinning technique for transforming a cheap raw material (industrial grade PU) to nanofibrous web for advanced applications.