Research

17 pages, 3907 KiB

Open AccessEditor’s ChoiceArticle

Tunable Wettability of Biodegradable Multilayer Sandwich-Structured Electrospun Nanofibrous Membranes

by A. K. M. Mashud Alam, Elena Ewaldz, Chunhui Xiang, Wangda Qu and Xianglan Bai

Polymers 2020, 12(9), 2092; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12092092 - 15 Sep 2020

Cited by 13 | Viewed by 3838

This research aims to develop multilayer sandwich-structured electrospun nanofiber (ENF) membranes using biodegradable polymers. Hydrophilic regenerated cellulose (RC) and hydrophobic poly (lactic acid) (PLA)-based novel multilayer sandwich-structures were created by electrospinning on various copper collectors, including copper foil and 30-mesh copper gauzes, to [...] Read more.

This research aims to develop multilayer sandwich-structured electrospun nanofiber (ENF) membranes using biodegradable polymers. Hydrophilic regenerated cellulose (RC) and hydrophobic poly (lactic acid) (PLA)-based novel multilayer sandwich-structures were created by electrospinning on various copper collectors, including copper foil and 30-mesh copper gauzes, to modify the surface roughness for tunable wettability. Different collectors yielded various sizes and morphologies of the fabricated ENFs with different levels of surface roughness. Bead-free thicker fibers were collected on foil collectors. The surface roughness of the fine fibers collected on mesh collectors contributed to an increase in hydrophobicity. An RC-based triple-layered structure showed a contact angle of 48.2°, which is comparable to the contact angle of the single-layer cellulosic fabrics (47.0°). The polar shift of RC membranes on the wetting envelope is indicative of the possibility of tuning the wetting behavior by creating multilayer structures. Wettability can be tuned by creating multilayer sandwich structures consisting of RC and PLA. This study provides an important insight into the manipulation of the wetting behavior of polymeric ENFs in multilayer structures for applications including chemical protective clothing. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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14 pages, 4073 KiB

Open AccessArticle

One-Pot Polymerization of Dopamine as an Additive to Enhance Permeability and Antifouling Properties of Polyethersulfone Membrane

by Sri Mulyati, Syawaliah Muchtar, Nasrul Arahman, Friska Meirisa, Yanna Syamsuddin, Zuhra Zuhra, Cut Meurah Rosnelly, Norazanita Shamsuddin, Normi Izati Mat Nawi, Mohd Dzul Hakim Wirzal, Muhammad Roil Bilad, Ryosuke Takagi and Hideto Matsuyama

Polymers 2020, 12(8), 1807; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12081807 - 12 Aug 2020

Cited by 14 | Viewed by 3422

Abstract

This paper reports the fabrication of polyethersulfone membranes via in situ hydrogen peroxide-assisted polymerization of dopamine. The dopamine and hydrogen peroxide were introduced into the dope solution where the polymerization occurred, resulting in a single-step additive formation during membrane fabrication. The effectivity of [...] Read more.

This paper reports the fabrication of polyethersulfone membranes via in situ hydrogen peroxide-assisted polymerization of dopamine. The dopamine and hydrogen peroxide were introduced into the dope solution where the polymerization occurred, resulting in a single-step additive formation during membrane fabrication. The effectivity of modification was evaluated through characterizations of the resulting membranes in terms of chemical functional groups, surface morphology, porosity, contact angle, mechanical strength and filtration of humic acid solution. The results confirm that the polydopamine was formed during the dope solution mixing through peroxide-assisted polymerization as proven by the appearance of peaks associated OH and NH groups in the resulting membranes. The presence of polydopamine residual in the membrane matric enhances the pore properties in terms of size and porosity (by a factor of 10), and by lowering the hydrophilicity (from 69° to 53°) which leads to enhanced filtration flux of up to 217 L/m² h. The presence of the residual polydopamine also enhances membrane surface hydrophilicity which improve the antifouling properties as shown from the flux recovery ratio of > 80%. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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11 pages, 1541 KiB

Open AccessArticle

Sorting Liquid Droplets by Surface Tension Using Devices with Quasi-Superamphiphobic Coatings

by Yu-Ping Zhang, Di Fan, Xiu-Zhi Bai, Cheng-Xing Cui, Jun Chen, Ren-Long Li, Peng-Fei Liu and Ling-Bo Qu

Polymers 2020, 12(4), 820; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040820 - 04 Apr 2020

Cited by 5 | Viewed by 2309

Abstract

Any solid surface with homogenous or varying surface energy can spontaneously show variable wettability to liquid droplets with different or identical surface tensions. Here, we studied a glass slide sprayed with a quasi-superamphiphobic coating consisting of a hexane suspension of perfluorosilane-coated nanoparticles. Four [...] Read more.

Any solid surface with homogenous or varying surface energy can spontaneously show variable wettability to liquid droplets with different or identical surface tensions. Here, we studied a glass slide sprayed with a quasi-superamphiphobic coating consisting of a hexane suspension of perfluorosilane-coated nanoparticles. Four areas on the glass slide with a total length of 7.5 cm were precisely tuned via ultraviolet (UV) irradiation, and droplets with surface tensions of 72.1–33.9 mN m⁻¹ were categorized at a tilting angle of 3°. Then, we fabricated a U-shaped device sprayed with the same coating and used it to sort the droplets more finely by rolling them in the guide groove of the device to measure their total rolling time and distance. We found a correlation between ethanol content/surface tension and rolling time/distance, so we used the same device to estimate the alcoholic strength of Chinese liquors and to predict the surface tension of ethanol aqueous solutions. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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14 pages, 2845 KiB

Open AccessEditor’s ChoiceArticle

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

by Jinwook Lee and Jooyoun Kim

Polymers 2020, 12(3), 721; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12030721 - 24 Mar 2020

Cited by 54 | Viewed by 8698

Abstract

Electret filters as opposed to mechanical filters display the enhanced ability to capture airborne particles with the electrostatic attraction. However, the environmental aging during shelf-life or use may cancel its benefit by dissipating the charges. This work investigates the polymeric attributes influencing the [...] Read more.

Electret filters as opposed to mechanical filters display the enhanced ability to capture airborne particles with the electrostatic attraction. However, the environmental aging during shelf-life or use may cancel its benefit by dissipating the charges. This work investigates the polymeric attributes influencing the charge decay and the electrostatic filtration of electret filters, employing polymers with different dielectric constants (ε_r) and wettability. As accelerated aging, high temperature (120 °C) or high humidity (25 °C, 90% RH) was applied to the electret filters for 48 h. For the humidity aging, wetting property of material was a critical factor affecting the charge decay and the filtration performance, as the absorbed water increases the electrical conductivity. For the thermal aging, the material with the highest ε_r deteriorated the electric potential and the filtration performance by the largest extent, due to the lower band gap energy for charge transfer. The results of this study implicate that ε_r and wettability are important material parameters influencing the electric conductivity and chain mobility, and they can be used as convenient predictors for charge retention capacity affecting the robust electrostatic filtration performance. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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16 pages, 7696 KiB

Open AccessArticle

Preparation of Bentonite/Chitosan Composite for Bleaching of Deteriorating Transformer Oil

by Hujian Chen, Kewang Zheng, Aohui Zhu, Zhifei Meng, Wei Li and Caiqin Qin

Polymers 2020, 12(1), 60; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12010060 - 01 Jan 2020

Cited by 3 | Viewed by 3526

Abstract

A novel adsorbent containing chitosan (CS) and bentonite (BT) was developed by mixing, drying, and calcining, and used as an adsorbent for the efficient bleaching of deteriorating transformer oil. The effects of calcination temperature, dosage of CS, adsorbent content, adsorption temperature, and adsorption [...] Read more.

A novel adsorbent containing chitosan (CS) and bentonite (BT) was developed by mixing, drying, and calcining, and used as an adsorbent for the efficient bleaching of deteriorating transformer oil. The effects of calcination temperature, dosage of CS, adsorbent content, adsorption temperature, and adsorption time on the bleaching capacity of transformer oil were investigated. The structure of the adsorbent was also investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and N₂ adsorption-desorption isotherm techniques. The results showed that there was only physical interaction between CS and BT; CS did transform to carbon (C) and covered the surface of BT. The specific surface area and micropore volume of the adsorbent were affected by the calcination process. The composite adsorbent offered an excellent bleaching performance. When the calcination temperature was 300 °C and dosage of CS was 5%, the composite adsorbent had the optimum bleaching properties. When the composite adsorbent content was 4%, the adsorption temperature was 50 °C and the adsorption time was 75 min, the colour number and transmittance of the deteriorating transformer oil decreased from no. 10 to no. 1 and increased from 70.1% to 99.5%, respectively. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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16 pages, 7866 KiB

Open AccessArticle

Design of Web-to-Web Spacing for the Reduced Pressure Drop and Effective Depth Filtration

by Sanghyun Roh, Kangsoo Park and Jooyoun Kim

Polymers 2019, 11(11), 1822; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11111822 - 06 Nov 2019

Cited by 17 | Viewed by 3254

Abstract

The study aims at lowering the pressure drop and extending the service life at a given set of filter materials implementing a space between the filter layers. As design factors, the web-to-web space was implemented by inserting either a bulk air gap or [...] Read more.

The study aims at lowering the pressure drop and extending the service life at a given set of filter materials implementing a space between the filter layers. As design factors, the web-to-web space was implemented by inserting either a bulk air gap or porous spacer web between the filter webs. The effect of spacing, either by the air gap or by the spacer web, on the pressure drop reduction was apparent for 4-layer constructions, and the effect was greater at the higher face velocity. The use of spacer web was more effective than the air gap in reducing the pressure drop, because the porous, fluffy spacer web acted as an effective air flow channel between the compact filter layers. The loading capacity was also increased with the spacer web implementation, effectively delaying the clogging point and extending the service life. Employing both experimental investigation and numerical simulation, this study intended to provide a practical design solution to the important problem in the field of air filtration. The results of this study can be used as a practical design guide to reduce pressure drop via depth filtration. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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Review

Jump to: Research, Other

24 pages, 3531 KiB

Open AccessReview

Advanced Design of Fiber-Based Particulate Filters: Materials, Morphology, and Construction of Fibrous Assembly

by Seojin Jung and Jooyoun Kim

Polymers 2020, 12(8), 1714; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12081714 - 30 Jul 2020

Cited by 48 | Viewed by 9116

Abstract

With increasing air pollution and sporadic outbreaks of epidemics, there is ramping attention on the filtration devices. The main constituents of airborne pollutants are particulate matters of solid particles, liquid aerosol, bioaerosol/bio-droplets, and gas/vapor. With the growing demand for high-performance filters, novel materials [...] Read more.

With increasing air pollution and sporadic outbreaks of epidemics, there is ramping attention on the filtration devices. The main constituents of airborne pollutants are particulate matters of solid particles, liquid aerosol, bioaerosol/bio-droplets, and gas/vapor. With the growing demand for high-performance filters, novel materials and functionalities are being developed applying advanced technologies. In this paper, recent developments of fiber-based particulate filters are reviewed, with a focus on the important performance parameters and material properties. Trends in technology and research activities are briefly reviewed, and the evaluative measures of filtration performance are reported. Recent studies on the advanced filter materials are reviewed in the aspect of polymers and the fabrication process of fibrous assembly. The characterization method including 3D modeling and simulation is also briefly introduced. Multifunctional filters such as antimicrobial filter and gas and particulate filters are briefly introduced, and efforts for developing environmentally sustainable filters are noted. Full article

(This article belongs to the Special Issue Polymeric Materials for Filtration and Purification)

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