Electrospun (e-spun) nanofiber materials have emerged as a prominent research focus owing to their extensive and promising potential applications across biomedical, energy, and environmental domains. Polyacrylonitrile (PAN) is a commonly used polymer for electrospinning (e-spinning). Due to insufficient hydrophilic properties of nitrile groups of PAN, its e-spun nonwoven membranes had low water absorption and moisture absorption, which limited application in medical and health fields. In this study, it was investigated that the hydrophilic modification of e-spun PAN nanofiber membrane (NFM) was conducted via Ritter reaction to convert nitrile groups into hydrophilic amide ones, thereby improving the hydrophilicity of PAN NFMs. The surface morphologies and structure of the modified e-spun fibers were characterized and verified by SEM, FTIR and XPS. After 60-90 min of Ritter reaction, the fiber diameter of the PAN NFM became thicker, transforming from a hydrophobic membrane to a hydrophilic one, and the water contact angle decreased from 124.2 to 40.7 degrees. The amidated PAN obtained membrane was post-treatment with sodium hypochlorite to make some amide groups change to N-halamine, which took the PAN NFM antibacterial activity or bacteriostasis. This work suggested a strategy that the espun PAN NFMs modified would have a promising application in medical dressings, air filtration, etc.

The airborne particulate matter (PM) poses a severe risk to human health worldwide, and developing high-temperature resistant material with high filtration performance is crucial for the effective removal of industrially generated PM. In this study, a novel double-layered composite nonwoven (CN) constructed with one layer of polyphenylene sulfide (PPS) needle-punching felt (NF) and one layer of polysulfone-amide (PSA) nanofiber mat (NM) was designed and implemented for potential high-temperature filtration application. In details, an electrospinning strategy was first employed to fabricate PSA NMs with adjustable fiber diameters. Then, a thermal-pressing post-treatment was utilized to realize the combination of PSA NM and commercial PPS NF, to generate a PSA/PPS CN. The electrospun PSA nanofibers were found to be uniformly covered on the PPS microfibers after the thermal-press process, resulting in a stable micro-/nano-fibrous structure. It was found that the PSA/PPS CN with the 120 μm thickness of nanofiber mat possessed 100

Emissions from power generation and municipal waste incineration sources are primarily at high temperatures and contain corrosive gases, particulate pollutants and are enormously challenging on the performance of the filtration systems in use. Here, polyphenylene sulfide (PPS) nonwoven fabric, a primary material used commercially in such settings, is modified with a polybenzoxazine precursor as a coating to deliver improved thermal and oxidation resistance to the fibrous substrate. The polybenzoxazine precursor undergoes chain propagation and crosslinking upon the treatment process to provide a protective layer over the PPS fibers such that enhanced structural stability in a harsh environment was demonstrated. We have shown the improved overall tensile strength (+15%), Young’s modulus (+26%), and more hydrophobic nature of the modified PPS fabric, while the superior environmental stability and better filtration performance could be achieved. Such methodology may lead to higher service temperature and extended service time of the PPS filtration bags in harsh fire exhaustion airstreams encountered in power plants or municipal garbage incineration facilities. The crosslinkable benzoxazine could also be the most cost-effective high temperature coating layer on fibers, enabling future high-performance air filtration materials.

Here, a multifunctional poly (lactic acid)/copper-based metal-organic framework (PLA/CuMOF) degradable composite membrane featuring superior antibacterial and self-cleaning properties was fabricated via a simple electrospinning process for high-efficiency filtration/separation. Benefiting from the decrease of fiber diameter, the improved surface roughness and the surface charge of CuMOF, PLA/CuMOF fibrous membrane achieved excellent capture ability for ultra-fine particles and superb purification capability for real PM2.5 smoke. The differences of filtration capacity between PLA membrane and PLA/CuMOF mem-brane was further explored using analogue simulation with dynamic particle capture and airflow field distribution. Impressively, PLA/CuMOF fibrous membrane combines robust self-cleaning ability, effective antibacterial effect, and thermal management capability. Moreover, owing to the special selective wettability and chemical stability, PLA/CuMOF membrane possessed the stable oil-water separation performance under harsh environment (e.g., high acid, alkali, and salt). This degradable multifunctional filtration/separation fibrous membrane emerges a broad application prospect ranging from environmental governance, industrial security to personal protection. (C) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Crude oil spills seriously harm the ocean environment and endanger the health of various animals and plants. In the present study, a totally biodegradable polymer, poly(L-lactic acid) (PLLA), was employed to fabricate highly porous oil absorbent nanofibrous materials by using a combination of electrospinning technique and subsequent acetone treatment. We systematically investigated how the electrospinning parameters affected formation of the porous structure of PLLA nanofibers and demonstrated that PLLA nanofibers with decreased and uniform diameter and improved porosity could be rapidly prepared by adjusting solution parameters and spinning parameters. We also demonstrated that the acetone treatment could obviously enhance the pore diameter and specific surface area of as-optimized electrospun PLLA nanofibers. The acetone treatment could also improve the hydrophobic property of as-treated PLLA nanofiber membranes. All these led to a significant increase in oil absorption performance. Through our research, it was found that the oil absorption of PLLA nanofiber membrane increased by more than double after being treated with acetone and the oil retention rate was also improved slightly.

As a high-performance fiber, high modulus polyethylene fiber (HMPE) has been widely used in the rope industry. However, due to its low melting point and poor thermal conductivity, it tends to break under the conditions of repeated yarn on yarn abrasion during tension-tension fatigue or tension-bending fatigue. This paper puts forward a method to improve the yarn on yarn abrasion performance of HMPE using a functional graphene/polyurethane composites coating (FG/PU) and discussed the influence of yarn tension, abrasion frequency on the yarn on yarn performance. Based on the yarn morphology and abrasion temperature observation, the failure mechanism was discussed. The experimental results show that the FG/PU coating obtained can improve the yarn on yarn abrasion performance obviously, especially in the case of high-frequency and large tension condition.

As a natural cellulose fiber, kapok fiber is much easier to degrade due to its thin wall structure of fiber in the process of storage and use. In this work, a finishing modification was designed and developed to prevent kapok fiber from degradation. Dopamine was polymerized in situ and deposited on the surface of kapok fiber, which was operated in the mixed solvents of ethanol:water (1:1 in volume) to overcome the strong buoyancy. Polyethyleneimine (PEI) was introduced to assist dopamine polymerization and improve the load rate. An optimum dosage, 1.0 g/ l of PEI could afford the highest loading rate of 32.1% of polydopamine (PDA), and remarkably improve loading fastness. As a multi-amino polymer, PEI could reduce Ag + and chelate with metal silver (Ag). The PDA/Ag covered kapok fiber and nonwovens showed good antibacterial activity and better mechanic strength, which would be more suitable for durable oil absorption and sound absorption materials than pure kapok fiber.

Development of a novel filter material is urgently required for replacing the high-cost flue gas purification technology in the simultaneous removal of both fine dust and Nitrogen oxides (NOx). In this study; polyphenylene sulfide (PPS) needle-punching fibrous felts (NPFF) were employed as the filter material to remove the fine dust; and in the meanwhile; Mn and Ce oxides were loaded onto the PPS NPFF as the catalyst for selective catalytic reduction of NOx with NH3. Two different pretreatment methods; i.e., sodium alginate (SA) deposition and plasma treatment; were employed to modify the PPS NPFF before the traditional impregnation and thermal treatment processes during the catalyst loading. The results showed that these two pretreatment methods both afforded the PPS NPFF with the enhanced loading rate and stability of Mn/Ce oxides compared to those without any pretreatments; which were significantly beneficial for the denitration application. Moreover; we found that both SA deposition and plasma pre-treated samples presented excellent dust-removal properties; and the filtration efficiency could reach 100% when the particle size of the fine particulates was above 4 μm. This study demonstrated that our Mn/Ce oxides decorated PPS NPFF have great potential to be applied in the fuel gas purification field; due to their stable structure; handling convenience; and excellent filtration efficiency; as well as high denitration performance.

Based on the construction strategy of proton transport channels, we design a high-performance proton exchange membrane (PEM) with ordered deoxyribonucleic acid(DNA)-functionalized graphene oxide (GO) and Nafion matrix via the electrostatic layer-by-layer deposition (ELD) technique, which is a novel method of membrane formation aided by electrostatic force. The effects of different content rations of single-strand DNA (ss-DNA) molecules and GO (ss-DNA@GO) on the proton conductivity, methanol permeability, and single cell performance of composite PEMs are investigated. The composite membrane shows a high proton conductivity of 351.8 mS cm(-1) (80 degrees C, 100%RH) but a low methanol permeability of 1.63 x 10(-7) cm(2) s(-1) at room temperature. Furthermore, the composite membranes are assembled into direct methanol fuel cells at 60 degrees C, and Nafion/DNA@GO-2/5 exhibits a maximum power density of 255.33 mW cm(-2), which is 2.42 times higher than that of pure Nafion. This work explores the application potential of DNA@GO in PEM and provides a bioinspired avenue to designing next-generation high-performance PEM for fuel cells. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

As soft elements for force transmission, braided fiber ropes play important roles in many fields where the fiber ropes are used bent over sheaves, while the relevant experiments are time-consuming and expensive. Computational simulation is a promising choice for evaluating the performance of fiber ropes when bent over a sheave. This article presents two methods that could be employed to build a model of braided rope bent over a sheave. One is the mathematical method which deduces the exact mathematical equations of braiding curves based on the Frenet–Serret frame. The spatial equations, considering the phase difference of strands in the same direction and the difference of strands’ projection in different directions, are discussed carefully. The final equation of braided strands is confirmed by modeling the braided rope in Maple ® 17. The other method, which is inspired by the analysis of braiding movements, is based on the intersection of surfaces of braiding surface and helical surface which are introduced and defined based on the motion analysis of bobbins and take-up roller. The SolidWorks ® 2018 is successfully employed to realize the modeling process.

Polypropylene (PP) fibers are employed commonly as the raw material of technical textiles (nonwovens), and the research focuses on fine-denier fibers and their functionalities. In this work, antibacterial PP masterbatches with different dosage (1–5 wt.%) of nano-ZnO particles as the antibacterial agent were prepared via a twin-screw extruder. The as-prepared PP masterbatches were electrospun on a home-made electrospinning device to afford ultra-fine PP fibers. The morphologies of as-spun ultrathin PP fibers with 16 μm of average diameter were observed by SEM. The structure and element distribution were characterized by means of energy-dispersive spectroscopy (EDS) and Fourier-transfer infrared spectroscopy (FTIR), respectively. There was some zinc obviously distributed on the surface when a dosage of ZnO more than 1 wt.% was used, which contributed to the antibacterial activity. The crystallinity of PP fibers was not affected strongly by the dosage of ZnO based on the differential scanning calorimetry (DSC) heating curves, while thermal decomposition improved with the increase in ZnO content, and the mechanical strength decreased predictably with the increase in inorganic ZnO content.

Nanofibers have been widely used for the construction of proton channels in proton exchange membranes (PEMs), and the optimization and control of proton channels have become a focus in this research area. In this work, we design and fabricate optimized and efficient proton transport channels in PEMs by introducing of sulfonated poly (ether sulfone) nanofiber with amino-modified SiO2 protuberance structures. The protuberance structures improve the strong interactions between the functional groups of nanofibers and matrix, resulting in an increased density of proton-conducting sites and improvement in membrane properties. Notably, Nafion/SPES/SiO2-3% possesses a low methanol permeability of 7.22 x 10(-7) CM2 S-1 and a high proton conductivity of 0.23 S cm(-1) at 80 degrees C in water. Consequently, the Nafion/SPES/SiO2 membrane demonstrates a maximum power density of 77.22 mW cm(-2) in a direct methanol fuel cell test system, which is 42.34% higher compared to the value of Nafion membrane (54.25 mW cm(-2)). This study successfully explores the preparation route of nanofiber with protuberance structures successfully, and highlights the potential benefits of this novel nanofiber structure in the PEM field.

Polyphenylene sulfide (PPS) is a semi-crystalline polymer with high performance, such as heat-resistance, chemicals resistance etc. The PPS fibers are widely applied in bag-filters to remove dust for end gas of industrial coal-fired plants. The deteriorated and broken PPS bag-filter was hard to detect in a device consisting of hundreds of bags. In this research, a conductive polymer, polyaniline (PANI) was in situ polymerized and deposited on the surface of PPS fibers. The loading content of PANI were affected by dropping speed of initiator, ammonium persulfate (APS) solution and slower dropping speed resulted in higher loading rate. The morphologies and properties of resulting PPS/PANI felt were characterized by means of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), tensile tester and Keithley 6487. The PPS fiber was coated on about 1.3 μm thickness of PANI, and the PPS/PANI felt has higher breaking force and elongation at break than those of pristine PPS one after ageing for 8 h at 200 °C, which the PPS/PANI composite fiber would show longer service life. PANI layer also offered the fiber conductivity, which would be used as a pressure sensor for PPS bag-filter when running.

Thermal damage is an important failure mechanism that affects the bending failure of fiber ropes. This is relevant because synthetic fibers often have a relatively low melting point and low thermal conductivity. In cyclic bending over sheave (CBOS), the heat generated by friction and deformation is not conducted rapidly to the external environment, and the temperature of the rope core increases quickly. This higher temperature greatly reduces the mechanical properties of the fiber, thus accelerating the final rope failure. In this paper, evidence of thermal damage in the bending process of a braided synthetic fiber rope is given. The test conditions inducing thermal damage are discussed, including stress level, bending frequency and diameter ratio. The reasons for the heat generation and the dynamic process of heat accumulation inside the rope during CBOS are also discussed. This study aims to provide theoretical and experimental guidance for the design and use of fiber rope.

Microfiber yarns (MY) have been widely employed to construct tendon tissue grafts. However, suboptimal ultrastructure and inappropriate environments for cell interactions limit their clinical application. Herein, we designed a modified electrospinning device to coat poly(lactic-co-glycolic acid) PLGA nanofibers onto polylactic acid (PLA) MY to generate PLGA/PLA hybrid yarns (HY), which had a well-aligned nanofibrous structure, resembling the ultrastructure of native tendon tissues and showed enhanced failure load compared to PLA MY. PLGA/PLA HY significantly improved the growth, proliferation, and tendon-specific gene expressions of human adipose derived mesenchymal stem cells (HADMSC) compared to PLA MY. Moreover, thymosin beta-4 (Tβ4) loaded PLGA/PLA HY presented a sustained drug release manner for 28 days and showed an additive effect on promoting HADMSC migration, proliferation, and tenogenic differentiation. Collectively, the combination of Tβ4 with the nano-topography of PLGA/PLA HY might be an efficient strategy to promote tenogenesis of adult stem cells for tendon tissue engineering.