Residual charge and filtration efficiency of polycarbonate fibrous membranes prepared by electrospinning

Abstract

Polycarbonate (PC) ultrafine fiber membranes with benzyl triethylammonium chloride (BTEAC) were prepared by electrospinning of PC/chloroform solution with different BTEAC contents. In the presence of BTEAC additive, the PC solution showed a better electrospinnability and led to thinner fibers with uniformity than the neat PC solution. The charge retention of the electrospun PC fibrous membranes with BTEAC was investigated in terms of additive content, membrane thickness and storage condition. The residual charge on the PC fibrous membrane was increased to 1 wt % BTEAC content, but thereafter gradually decreased up to 10 wt % BTEAC. In addition, the residual charge on the membrane was increased with increasing the membrane thickness, but was rapidly decreased at a high humidity condition in comparison with a low humidity. The filtration efficiency was examined for the fibrous membranes with or without BTEAC. The PC membrane with BTEAC had higher filtration efficiency than one without BTEAC, not affecting the pressure drop. The filtration efficiency between the PC membranes with or without residual charge was also compared. When the residual charge existed on the membrane, the membrane showed higher filter efficiency because of the enhanced filtration effect by an electrostatic attraction. Therefore, the PC fibrous membranes with BTEAC have a great potential as an electrets filter for air filtration.

Er-doped ZnO nanofibers for high sensibility detection of ethanol

“…Among them, electrospinning has been proven to be an effective, versatile, simple and low-cost method to produce high gas sensing performances due to the ultrahigh surface-to-volume ratio [19,24]. More recently, it has been demonstrated that metallic doping could be used to improve the sensitivity of ZnO-based gas sensors [24][25][26][27][28][29][30][31]. Mao A c c e p t e d M a n u s c r i p t ethanol could be 5 times higher than that of pure ZnO samples [27].…”

“…However, for Er-doped ZnO samples, the average diameters of 0.5 at%, 1.0 at% and 2.0 at% Er-doped ZnO nanofibers are about 165 ± 42 nm, 130 ± 35 nm and 70 ± 23 nm, respectively. It can be clearly observed that the addition of small amounts of Er to the ZnO nanofibers led to a significant decrease of the fiber diameters but an increase in fibers uniformity.These changes in fibers morphology are due probably to the increase of the conductivity of the precursor solutions caused by the increase of salts (Er(NO 3 ) 3 ·6H 2 O)[29].…”

Material Properties Influencing the Charge Decay of Electret Filters and their Impact on Filtration Performance

“…In this process, the material in an intense electric field acquires charges, then the charges are frozen at cooling [4]. The electric field in electrets is sourced from the internal polarization of a dielectric or the externally accumulated electric charges [1,[4][5][6]. Another simple classification of electrets is hetero-electrets and homo-electrets; where homo-electret mostly occurs by excess charge injection into nonpolar materials, and hetero-electret occurs through the internal charging by orientation of dipoles [3].…”

“…The electret filter as opposed to the mechanical filter display enhanced ability of capturing airborne particles due to the benefit of coulombic attraction and induced polarization. Thus, electret filters tend to give higher quality factor (QF), which is the relative efficiency to a unit pressure drop [6,22,23]. The limitation of electret filter comes from the charge decay, which occurs through environmental aging that causes electric conduction or charge carrier mobility [8,[16][17][18].…”

High filtration efficiency fluffy material: nano-fiber constructing gradient structure on recycled curved PET micro-fibers web

“…During electrospinning process, a high voltage electric field forms between the tip of needle and the collection layer, thus polarized charges resident on the surface of fiber, which cannot dissipate immediately. The residual charges enhance the temporary filtration ability [45,46]. Tendency of charge dissipation depends on properties of fiber materials itself such as conductivity and hydrophobic or hydrophilic.…”