ABSTRACT
The global outbreak of COVID-19 results in the surge of disposable sanitary supplies, especially personal protective face masks. However, the charge dissipation of the electret meltblown nonwovens, which predominate in the commercial face mask filters, confines the durability and safety of commercial face masks. Furthermore, most of the face masks are made from nondegradable materials (such as PP) or part of their degradation products are toxic and contaminative to the environment. Herein, a type of face mask with biodegradable and highly effective PLA bi-layer complex fibrous membrane as filter core is reported. The prepared PLA complex membrane possesses a high-filtration efficiency of 99.1% for PM0.3 while providing a favorable pressure drop of 93.2 Pa. With the PLA complex membrane as the filter core, our face mask exhibits comparable or even higher wearability to commercial face masks, which further manifests our designed PLA complex membrane a promising filter media for face masks. © 2023, The Author(s), under exclusive licence to the Korean Fiber Society.
ABSTRACT
With the emergence of the COVID-19, masks and protective clothing have been used in huge quantities. A large number of non-degradable materials have severely damaged the ecological environment. Now, people are increasingly pursuing the use of environmentally friendly materials to replace traditional chemical materials. Silk fibroin (SF) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) have received increasing attention because of their unique biodegradability and biocompatibility. In this paper, a series of biodegradable SF/PHBV nanofiber membranes with different PHBV content were fabricated by using electrospinning technology. The morphology of the electrospun SF/PHBV composite nanofiber was observed by scanning electron microscopy (SEM). The average diameters of the pure SF, SF/PHBV (4/1), SF/PHBV (3/1), and SF/PHBV (2/1) nanofibers were 55.16 ± 12.38 nm, 75.93 ± 21.83 nm, 69.35 ± 21.55 nm, and 61.40 ± 12.31 nm, respectively. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were used to explore the microstructure of the electrospun SF/PHBV composite nanofiber. The crystallization ability of the composite nanofiber was greatly improved with the addition of PHBV. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated that the thermal stability of SF was better than PHBV obviously, so SF could improve the thermal stability of the composite materials within a certain range. The mechanical properties of the electrospun nanofiber membranes were evaluated by using a universal testing machine. In general, the elongation of the composite nanofiber membranes decreased, and the breaking strength increased with the addition of PHBV. The small pore size of the nanofiber membranes ensured that they had good application prospects in the field of filtration and protection. When the spinning time was 1 h, the filtration efficiency of SF/PHBV/PLA composite materials remained above 95%. © 2021 The Textile Institute.
ABSTRACT
[Display omitted] • Nylon-6 micro-nanofiber composite membranes had uniform space gradient structure. • Composite membranes had good filtration performance against ultrafine particles. • The masks had stable protection performance and comfortable wearing experience. Compared of traditional melt-blown nonwoven materials, micro-nanofiber composite membranes with uniform spatial gradient structure will be the development trend of high efficiency and low resistance filtration materials, especially against ultrafine particles with kinetic diameter less than 0.25 (PM 0.25). Herein, Nylon-6 micro-nanofiber composite membranes (Nylon-6 FCMs) with three-dimensional (3D) uniform gradient structure were prepared by air jet spinning under the help of PEO. The fluffy 3D gradient structure possessed a uniform gradual pore gradient from large to small, ensuring the PM 0.25 were captured by exact grading under high gas flow due to the form of special "trumpet-like" gas passage inside the membranes. The structure of Nylon-6 FCMs could be controlled and exhibited high tensile strength, good moisture permeability, excellent filtration performance. Among them, the FCM-1 with a uniform gradual pore gradient could achieve the optimal filtering performance with filtration efficiency (99.99 %) and pressure drop (144 Pa). The mask prepared using this Nylon-6 FCMs also displayed good protective effect with comparable air permeability (221.84 mm·s−1) and moisture permeability (181.84 g·m−2·h−1) compared of commercial melt-blown masks. Most importantly, this mask prepared still could maintain good filtration performance even in high temperature and high humidity environment, providing users more comfortable wearing experience and stable protection performance, especially under the current COVID-19 outbreak. [ FROM AUTHOR]
ABSTRACT
Particulate matter and spread of viruses, including COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are two of the most serious problems because of their significant threat to human health. Here, we fabricate ultrafine and bimodal structured polyamide-6 nanofiber/nets (PA-6 NFN) membrane via one-step electrospinning/netting. The PA-6 NFN membranes include ultrafine (∼70 nm) nanofibers and two-dimensional (2D) ultrathin (∼20 nm) nanonets. These membranes are optimized by facilely regulating the solution concentration, incomplete phase separation by adding NaCl, and also applying a high voltage of 22 kV. With integrated properties of small pore size, high porosity, high specific surface area of 108.8 m2/g, and robust tensile strength of 13.70 MPa, the resultant PA-6 NFN membranes exhibit high filtration efficiency of 99.11%, low pressure drop of 81 Pa, and higher quality factor compared to the two standard commercial masks which consist of three-ply surgical mask and respirator face mask. It can include bacteria, fungi, and also viruses including SARS-CoV-2 (with a diameter of about 100 nm). Additionally, after 24 h of operation of the filtration process in a simulated living environment, the obtained air filter still displayed a high filtration efficiency and a less variation pressure drop that shows the long-term performance of PA-6 NFN membranes. In addition, the R2 value was 0.99, which indicates that the calculation results are in good agreement with the measured results. The fabrication of PA-6 NFN membrane makes it a promising candidate for PM0.3 governance at applications including face mask, protective clothing, clean room, and engine intake. © The Author(s) 2022.
ABSTRACT
Face masks act as air filters that collect droplets and aerosols, and they are widely used to prevent infectious diseases, such as COVID-19. Herein, we present a numerical simulation model to understand the collection behavior of aerosols containing submicron-sized droplets inside a realistic microstructure of commercially available face masks. Three-dimensional image analysis by x-ray computed tomography is used to obtain the microstructures of two types of commercial face masks, and the aerosol permeation behavior in the obtained microstructures is investigated with a numerical method coupled with computational fluid dynamics and a discrete phase model. To describe the complex geometry of the actual fibers, a wall boundary model is used, in which the immersed boundary method is used for the fluid phase, and the signed distance function is used to determine the contact between the droplet and fiber surface. Six different face-mask domains are prepared, and the pressure drop and droplet collection efficiency are calculated for two different droplet diameters. The face-mask microstructure with the relatively larger pore, penetrating the main flow direction, shows a high quality factor. A few droplets approach the pore accompanied by fluid flow and fibers collect them near the pore. To verify the effect of the pore on the collection behavior, six different model face-mask domains of variable pore sizes were created. Additionally, droplet collection near the pore is observed in the model face-mask domains. Specific pore-sized model masks performed better than those without, suggesting that the large pore may enhance performance.
ABSTRACT
Compared of traditional melt-blown nonwoven materials, micro-nanofiber composite membranes with uniform spatial gradient structure will be the development trend of high efficiency and low resistance filtration materials, especially against ultrafine particles with kinetic diameter less than 0.25 (PM0.25). Herein, Nylon-6 micro-nanofiber composite membranes (Nylon-6 FCMs) with three-dimensional (3D) uniform gradient structure were prepared by air jet spinning under the help of PEO. The fluffy 3D gradient structure possessed a uniform gradual pore gradient from large to small, ensuring the PM0.25 were captured by exact grading under high gas flow due to the form of special "trumpet-like” gas passage inside the membranes. The structure of Nylon-6 FCMs could be controlled and exhibited high tensile strength, good moisture permeability, excellent filtration performance. Among them, the FCM-1 with a uniform gradual pore gradient could achieve the optimal filtering performance with filtration efficiency (99.99%) and pressure drop (144 Pa). The mask prepared using this Nylon-6 FCMs also displayed good protective effect with comparable air permeability (221.84 mm·s-1) and moisture permeability (181.84 g·m-2·h-1) compared of commercial melt-blown masks. Most importantly, this mask prepared still could maintain good filtration performance even in high temperature and high humidity environment, providing users more comfortable wearing experience and stable protection performance, especially under the current COVID-19 outbreak.
ABSTRACT
SARS-CoV-2, the virus that caused the COVID-19 pandemic, can remain viable and infectious on surfaces for days, posing a potential risk for fomite transmission. Liquid-based disinfectants, such as chlorine-based ones, have played an indispensable role in decontaminating surfaces but they do not provide prolonged protection from recontamination. Here a safe, inexpensive, and scalable membrane with covalently immobilized chlorine, large surface area, and fast wetting that exhibits long-lasting, exceptional killing efficacy against a broad spectrum of bacteria and viruses is reported. The membrane achieves a more than 6 log reduction within several minutes against all five bacterial strains tested, including gram-positive, gram-negative, and drug-resistant ones as well as a clinical bacterial cocktail. The membrane also efficiently deactivated nonenveloped and enveloped viruses in minutes. In particular, a 5.17 log reduction is achieved against SARS-CoV-2 after only 10 min of contact with the membrane. This membrane may be used on high-touch surfaces in healthcare and other public facilities or in air filters and personal protective equipment to provide continuous protection and minimize transmission risks.