Electrospun waterproof breathable membrane with a high level of aerosol filtration

Abstract

In this study, several nanofibrous polyurethane (PU) webs were electrospun (ES) by changing different effective parameters (e.g., polymeric concentration, voltage, feed flow, etc.). The physical-chemical properties of the webs (i.e., average fiber diameters, thickness, areal density, porosity, contact angle, waterproofness, air permeability (AP), water vapor transmittance, and aerosol filtration) were studied based on the standard test methods. A commercially available waterproof breathable (WPB) fabric was used as a reference for benchmarking. The beads-free webs with an average fiber diameter as small as 200 nm were achieved from electrospinning of 10 wt % PU in N,N-dimethylformamide, at feed rate of 0.5 mL/h, applied voltage of 25 kV, and tip-to-collector distance of 15 cm. By optimizing the electrospinning parameters, a web with a high level of waterproofness, high AP, and high water vapor transmission rate (WVTR) was obtained. In addition, the selected ES membrane showed very promising aerosol filtration efficiency with complete removal of particles larger than 0.5 mm, and 94% reduction in the concentration of smaller particles. We found a linear empirical equation for the estimation of AP and WVTR based on the average pore size diameter, the membrane thickness, and the porosity with very high regression coefficients (R 2 > 0.97).

Electrospun nanofibrous polyvinylidene fluoride‐co‐hexafluoropropylene membranes for oil–water separation

“…In previous study, we investigated the effects of various electrospinning parameters (i.e., polymer concentration/viscosity, polymer solution feed rate, applied voltage, and the tip to collector distance) on the average fiber diameter and porosity of the fabricated membranes in a series of papers. [ 30,34,35 ] We also found in our previous study [ 20 ] that the addition of only 10 wt.% poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) to polyurethane can change the physical–chemical properties of the fabricated electrospun membrane (e.g., the average fiber diameter, pore size, the hydrostatic pressure head, etc.). The presence of HFP groups in the polymer improve hydrophobicity, [ 36 ] mechanical properties, [ 37 ] thermal and chemical stabilities, [ 38 ] and antifouling properties [ 39 ] of the resulting membrane.…”

“…The formation of these beads can be a sign of (a) improper solvent composition, (b) very high applied voltage, (c) low polymer concentration and viscosity, or (d) short time of flight as a result of low TCD. [ 30 ]…”

“…At the TCD <11 cm, the beads appeared in the membrane as the time of flight for the electrospun jet was too short for the complete stretching and fiber formation. [ 30 ] At such small distances, the potential difference between the tip and collector induced rapid and extended stretching of the polymer, hence decreasing its entropy. In this case, the polymer would maximize the entropy by forming beads.…”

Unsupported electrospun membrane for water desalination using direct contact membrane distillation

“…The flow of saturated air (Q), passing through the membrane was steadily increased, and the resultant pressure difference (ΔP) was measured. The pore size distribution was then calculated based on the measured flow rate (Q) as a function of pressure difference (ΔP) 34 . The LEP of the hydrophobic porous membranes was also measured with the capillary flow porometer.…”

Electrospun polymer blend with tunable structure for oil–water separation

“…28 The optimum ES conditions were determined by performing a series of screening experiments and the values from our previous publication. 29 The collector was covered with a nylon screen fabric. The voltage (V) and distance (TCD) between the tip of the nozzle and the collector were adjusted at 20 kV and 21 cm, respectively.…”