Preparation and Properties of an Efficient Purification Material for Personal Protection

At present, the filtration of virus and other small particles in the air by meltblown cloth produced by electret treatment mainly depends on its electrostatic adsorption mechanism. However, because the surface charge of melt blown fabric can not be maintained for a long time, it can not maintain high efficiency filtration for a long time. Therefore, there is no guarantee for the medical staffs to not be infected by COVID-19. Therefore, it is necessary to improve the mechanical filtration efficiency of melt blown fabric in the situation of an electric charge loss. In this paper, nylon 6 (PA6) nanofibers were electrospun on melt blown cloth by electrospinning technology, and a sandwich material with melt blown cloth as surface layer and PA6 nanofibers as middle layer was made by hot- pressing technology;the surface morphology, thermal and mechanical properties of the sandwich material were characterized, and its filtration performance was tested. The experimental results show that the surface integrity of the sandwich material is high, and the diameter of nanofibers can reach about 67 nm;without the electret treatment, the filtration efficiency of the sandwich material for particles in an size of 0.2 μm is more than 95%,while the filtration efficiency of non-woven fabric is zero;the filtration resistance of the material is about 284 Pa, which is suitable for personal protection. © 2023 Chengdu University of Science and Technology. All rights reserved.

Dual-Network Structured Nanofibrous Membranes with Superelevated Interception Probability for Extrafine Particles.

Airborne particulate matter (PM) pollution has caused a public health threat, including nanoscale particles, especially with emerging infectious diseases and indoor and vehicular environmental pollution. However, most existing indoor air filtration units are expensive, energy-intensive, and bulky, and there is an unavoidable trade-off between low-efficiency PM0.3/pathogen interception, PM removal, and air resistance. Herein, we designed and synthesized a two-dimensional continuous cellulose-sheath/net with a unique dual-network corrugated architecture to manufacture high-efficiency air filters and even N95 particulate face mask. Combined with its sheath/net structured pores (size 100-200 nm) consisting of a cellulose framework (1-100 nm diameter), the cellulose sheath/net filter offers high-efficiency air filtration (>99.5338%, Extrafine particles; >99.9999%, PM2.5), low-pressure drops, and a robustness quality factor of >0.14 Pa-1, utilizing their ultralight weight of 30 mg/m2 and physical adhesion and sieving behaviors. Simultaneously, masks prepared with cellulose-sheath/net filters are more likely to capture and block smaller particles than the N95 standard. The synthesis of such materials with their nanoscale features and designed macrostructures may suggest new design criteria for a novel generation of high-efficiency air filter media for different applications such as personal protection products and industrial dust removal.

Efficient, Breathable and Biodegradable Filter Media for Face Masks

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.

Preparation and property of electrospining nanocopper oxide antibacterial composite nonwovens

The spread and variation of COVID-19 in the world have seriously threatened human health. Therefore the current focus of research is to develop medical and antiepidemic textiles with high filtering efficiency and bacteriostasis and low filtering resistance. Polypropylene PP melt-blown nonwovens are commonly used as raw materials for medical antiepidemic textiles. PP melt-blown nonwovens as the core filter layer of medical textiles were difficult to buy during the outbreak of the epidemic. However the traditional PP melt-blown nonwovens have low antibacterial performance and medical staff are vulnerable to virus infection and microbial damage in the process of use for their single function and certain limitations in protective ability. Therefore in the post-pandemic era PP melt-blown nonwovens should not only be able to meet the rigid demand of the market but also evolve to be high-end and functional in the face of mutating COVID-19 and the possibility of a return at any time. The research combines the PP melt-blown nonwoven with the electrospinning nanofiber membrane to prepare compound nonwoven fabrics with high antibacterial activity. In order to improve the antibacterial property of PP melt-blown nonwovens composite nanofiber membranes were synthesized on PP melt-blown nonwovens by electrospinning technology. Firstly the PP melt-blown nonwoven was used as receiving substrate of electrospinning equipment and nano copper oxide CuO-NPS was used as anti-bacterial material to prepare the PP / PAN / CuO-NPS composite nonwovens with high antibacte-rial performance. On the basis of that effects of the CuO-NPS mass fraction and electrospinning time on the surface morphology fiber diameter distribution chemical constitution filtration performance hydrophobicity and antibacterial property of composite nonwovens were studied. The results show that the bacteriostasis rates of composite nonwovens to gram-negative E. coli and gram-positive S. aureus are both greater than 99. 99% in the range of CuO-NPS mass fraction of 0. 3% - 0. 9% and the spinning time is 1 h. When the spinning time is 1 h as the mass fraction of CuO-NPS increases the fiber diameter of the composite nonwoven increases and its distribution uniformity of diameter and hydrophobic property both decrease. Under the condition of constant mass fraction of CuO-NPS the filtration efficiency of composite nonwovens improves with the extension of the spinning time but the permeability decreases. With the same spinning time the filtration efficiency of composite nonwovens increases with the increase in CuO-NPS mass fraction. In addition in-corporating CuO-NPs into PAN nanofiber membrane does not change the chemical structure of the membrane. We select polyacrylonitrile PAN with good spinning performance as the raw material and CuO-NPs as the antibacterial material to prepare CuO-NPs powder with antibacterial properties to prepare electrostatic spinning solution. The composites of PP melt-blown nonwovens and electrospun PAN / CuO-NPs nanofibrous membrane have been obtained which not only improves the filtration performance of PP melt-blown nonwovens but also endows them with efficient antibacterial property. This paper provides a reference for further studies on the production and application of PP melt-blown nonwovens. (English) [ABSTRACT FROM AUTHOR] 针对聚丙烯( PP)熔喷非织造布抗菌性能不足的问题,本文以 PP 熔喷非织造布为静电纺丝装置的接受基布、 CuO-NPs 为抗菌材料,制备具有高效抗菌性能的聚丙烯 / 聚丙烯腈 / 纳米氧化铜( PP / PAN / CuO-NPs) 复合非织造布。 研究了 CuO-NPs 质量分数 与 静 电 纺 丝 时 间 对 复 合 非 织 造 布 抗 菌 等 性 能 的 影 响。 结 果 表 明:当 纺 丝 时 间 为 1 h、 CuO-NPs 质量分数在 0. 3% ~ 0. 9% 时,复合非织造布对 E. coli 和 S. aureus 的抑菌率均 > 99. 99% 。 纺丝时间为 1 h, 随着 CuO-NPs 质量分数增大,复合非织造布纤维直径增大、直径分布均匀性降低、疏水性能下降。 CuO-NPs 质量分 数不变,随着纺丝时间增加,复合非织造布的过滤效率提升,透气性却下降。 纺丝时间相同,复合非织造布的过滤效 率随着 CuO-NPs 质量分数增大而增大;CuO-NPs 质量分数增大时,复合非织造布的透气性在较短纺丝时间( 0. 5 ~ 1 h)内先下降后提升,在较长纺丝时间(1. 5 ~ 2. 5 h)内显著下降。 此外,CuO-NPs 的加入不会改变 PAN 纳米纤维膜 的化学结构。 静电纺纳米纤维膜与 PP 基布的复合可以制备高效过滤和抑菌的医用防疫纺织品。 (Chinese) [ABSTRACT FROM AUTHOR] Copyright of Journal of Silk is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Smart textiles for personal protection equipment (PPE)

Before Covid-19 and up to January 2020, the majority of facemasks, in addition to most other PPE items such as surgical gowns, medical scrubs, caps shoe covers, and disposable bedding were treated as commodity textiles and made in Asia, and most of them in China. All of them are single-use products based on synthetic fibres derived from petrochemicals, primarily polypropylene. This resulted in a 15,000-ton mountain of waste being created every 24h - most of which at present has to be incinerated. This does not even start to touch the huge amount of consumer facemasks which are now suddenly required, having been made compulsory for many activities and situations in many countries. This is the issue which now needs to be addressed at the fibre and fabric level - as well as with new end-of-life solutions - for items of PPE to become truly smart products. © 2023 Elsevier Ltd. All rights reserved.

A green strategy to recycle the waste PP melt-blown materials: From 2D to 3D construction.

The demand for polypropylene (PP) melt-blown materials has dramatically increased due to the COVID-19 pandemic. It has caused serious environmental problems because of the lack of effective treatment for the waste PP melt-blown materials. In this study, we propose a green and sustainable recycling method to create PP sponges from waste PP melt-blown material for oil spill cleaning by freeze-drying and thermal treatment techniques. The recycling method is simple and without secondary pollution to the environment. The developed recycling method successfully transforms 2D laminar dispersed PP microfibers into elastic sponges with a 3D porous structure, providing the material with good mechanical properties and promotes its potential application in the field of oil spill cleaning. The morphology structure, thermal properties, mechanical properties, and oil absorption properties are tested and characterized. The PP sponges with a three-dimensional porous network structure show an exceedingly low density of >0.014 g/cm3, a high porosity of <98.77 %, and a high water contact angle range of 130.4-139.9°. Moreover, the PP sponges own a good absorption capacity of <47.61 g/g for different oil and solvents. In particular, the compressive modulus of the PP sponges is 33.59-201.21 kPa, which is higher than that of most other fiber-based porous materials, indicating that the PP sponges have better durability under the same force. The excellent comprehensive performance of the PP sponges demonstrates the method developed in this study has large application potential in the field of the recycle of waste PP melt-blown materials.

A Short and Highly Efficient Method for Producing Meltblown Nano Yarn with a Helical Structure and High Conductivity

The COVID-19 outbreak has led to the overproduction of meltblown fabrics commonly used in personal protective equipment such as face mask. Moreover, the yield ofconventional fabrication methods for meltblown fabrics have poor mechanical properties and lack accessional value and functional applicability. In this study, a short and highly efficient process was employed to produce polypropylene/polypyrrole (PPy) meltblown nanoyarn (PPMNY). The mechanical properties were improved by utilizing a helical structure, and the conductivity was enabled using a combination of PPy nanoparticles. The breaking force of the proposed PPMNY was as high as 10.1cN/tex at 9T/10 cm, nearly 3.3 times more than PPMNY without the helical structure. The breaking force of the proposed PPMNY was unaffected by the washing process, and the frictional properties and snarling information were similarly maintained by the helical structure. Additionally, the optimal conductivity of the proposed PPMNY reached 0.044S·m-1. Therefore, the novel methods investigated in this study can improve the properties of meltblown fabrics to yield a highly efficient and low-cost technique to produce conductive PPMNY. This concept can be extended for solving the problems of the single two-dimensional structure with poor mechanical properties and application on Smart Wearable with preferable conductivity. © Textile Bioengineering and Informatics Symposium Proceedings 2022 - 15th Textile Bioengineering and Informatics Symposium, TBIS 2022.

Polyimide Surface Dielectric Barrier Discharge for Inactivation of SARS-CoV-2 Trapped in a Polypropylene Melt-Blown Filter

Surface dielectric barrier discharge (SDBD) was used to inactivate the infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) trapped in a polypropylene (PP) melt-blown filter. We used a dielectric barrier made of polyimide films with hexagonal holes through which air flowed. In a cylindrical wind tunnel, the SDBD device supplied reactive oxygen species such as ozone to the SARS-CoV-2 trapped in the PP filter. A plaque assay showed that SDBD at an ozone concentration of approximately 51.6 ppm and exposure time of 30 min induced more than 99.78% reduction for filter-adhered SARS-CoV-2. A carbon catalyst after SDBD effectively reduced ozone exhaust below 0.05 ppm. The combination of SDBD, PP filter, and catalyst could be a promising way to decrease the risk of secondary infection due to indoor air purifiers.

Mitigation of microfibers release from disposable masks - An analysis of structural properties.

The use of disposable face masks increased rapidly among the general public to control the COVID-19 spread. Eventually, it increased the disposal of masks and their associated impacts on environmental pollution. Hence, this study aims to analyze the impact of nonwoven fabric structural parameters and weathering on the microfiber release characteristics. Spunbond polypropylene nonwoven with four different weights and meltblown nonwoven with two different weights were used in this study to analyze microfiber release at dry, and wet conditions to simulate improper disposal in the environment. Exposure to sunlight significantly increases the microfiber release from 35 to 50% for spunbond fabric and 56-89% for meltblown fabric. Weathering in sunlight structurally affected the tensile properties of the polypropylene fibers due to photodegradation. The study showed that each mask can produce 1.5 × 102 and 3.45 × 101 mg of microfiber/mask respectively in dry and wet states. In the case of structural parameters, a higher GSM (grams per square meter), abrasion resistance, bursting strength, and thickness showed a positive correlation with microfiber release in both fabrics. Significantly a higher microfiber release was reported with meltblown fabric than the spunbond for a given GSM. The presence of finer fibers and more fibers per unit area in meltblown fabric was noted as the main cause. Nonwoven fabric GSM and the number of fibers in a specific area showed a higher influence on microfiber release. Based on the mask consumption reported in the literature, India alone can produce around 4.27 × 102 tons of microfibers/week as an average of dry and wet conditions. The study suggests that the proper selection of physical parameters can significantly reduce the microfiber fiber release at all stages.

Single-Side Superhydrophobicity in Si3N4-Doped and SiO2-Treated Polypropylene Nonwoven Webs with Antibacterial Activity.

Meltblown (MB) nonwovens as air filter materials have played an important role in protecting people from microbe infection in the COVID-19 pandemic. As the pandemic enters the third year in this current global event, it becomes more and more beneficial to develop more functional MB nonwovens with special surface selectivity as well as antibacterial activities. In this article, an antibacterial polypropylene MB nonwoven doped with nano silicon nitride (Si3N4), one of ceramic materials, was developed. With the introduction of Si3N4, both the average diameter of the fibers and the pore diameter and porosity of the nonwovens can be tailored. Moreover, the nonwovens having a single-side moisture transportation, which would be more comfortable in use for respirators or masks, was designed by imparting a hydrophobicity gradient through the single-side superhydrophobic finishing of reactive organic/inorganic silicon coprecipitation in situ. After a nano/micro structural SiO2 precipitation on one side of the fabric surfaces, the contact angles were up to 161.7° from 141.0° originally. The nonwovens were evaluated on antibacterial activity, the result of which indicated that they had a high antibacterial activity when the dosage of Si3N4 was 0.6 wt%. The bacteriostatic rate against E. coli and S. aureus was up to over 96%. Due to the nontoxicity and excellent antibacterial activity of Si3N4, this MB nonwovens are promising as a high-efficiency air filter material, particularly during the pandemic.

Correlation of antibacterial performance to electrostatic field in melt-blown polypropylene electret fabrics

Respirators have become popular personal protective equipment since the COVID-19 pandemic. The key material in respirators is the melt-blown polypropylene electret fabric (MBPPEF). In this article, the filtering and inactivating effects of electrostatic fields in the respirator materials on Staphylococcus aureus (S. aureus) are studied. As a typical airborne microorganism, S. aureus is often employed to evaluate the antibacterial performance of air filtration equipment. The results prove that the electrostatic field in MBPPEF plays the key role in filtrating S. aureus. All MBPPEF from different charging method can have a filtering efficiency of more than 99% against S. aureus. The inactivation rate of positive corona charged sample is the highest. The charging method will affect the formation of electrostatic fields in the MBPPEF, thereby affecting their antibacterial performance. © 2022

Polylactic acid face masks: Are these the sustainable solutions in times of COVID-19 pandemic?

The global massive consumption of disposable face masks driven by the ongoing COVID-19 pandemic has emerged as a blooming disaster to both the land and marine environment that might last for generations. Growing public concerns have been raised over the management and control of this new form of plastic pollution, and one of the proposed sustainable solution is to use renewable and/or biodegradable resources to develop mask materials in order to minimize their environmental impacts. As a representative biodegradable polymer, polylactic acid (PLA) has been proposed as a promising candidate to produce non-woven face masks instead of those fossil-based polymers. To further explore the feasibility of this alternative mask material, the present work aims to study both the hydrolytic and bio-degradation behaviors of pure PLA-derived 3-ply disposable face masks at ambient temperature. Hydrolytic degradability was investigated at different pH conditions of 2, 7 and 13 with the whole piece of face mask soaked for regular timed intervals up to 8 weeks. Weight loss study showed neutral and acidic conditions had minimal effect on PLA masks, but rapid degradation occurred under basic conditions in the first week with a sharp 25% decrease in weight that slowly tapered off, coupled with solution pH dropping from 13 to 9.6. This trend was supported by mechanical property, bacterial filtration efficiency (BFE) and particulate filtration efficiency (PFE) studies. Masks soaked in basic conditions had their modulus and tensile strength dropped by more than 50% after 8 weeks where the middle layer reached 68% and 90% respectively just after 48 h, and BFE and PFE decreased by 14% and 43% respectively after 4 weeks, which was much more significant than those in neutral and acidic conditions. Base degradation was also supported by nuclear magnetic resonance (NMR) and fourier transform infrared (FTIR), which disclosed that only the middle layer undergo major degradation with random chain scission and cleavage of enol or enolate chain ends, while outer and inner layers were much less affected. Scanning electron microscopy (SEM) attributed this observation to thinner PLA fibers for the middle layer of 3-7 µm diameter, which on average is 3 times smaller. This degradation was further supported by gel permeation chromatography (GPC) which saw an increase in lower molecular weight fragment Mw ~ 800 Da with soaking duration. The biodegradation behavior was studied under OECD 301F specification in sewage sludge environment. Similarly, degradation to the middle meltblown layer was more extensive, where the average weight loss and carbon loss was 25.8% and 25.7% respectively, double that of outer/inner spunbond layer. The results showed that the face masks did not completely disintegrate after 8 weeks, but small solubilized fragments of PLA formed in the biodegradation process can be completely mineralized into carbon dioxide without generation of secondary microplastic pollution in the environment. PLA masks are therefore a slightly greener option to consider in times of a pandemic that the world was caught unprepared; however future research on masks could be geared towards a higher degradability material that fully breaks down into non-harmful components while maintaining durability, filtration and protection properties for users.

Post COVID-19 pandemic: Biofragmentation and soil ecotoxicological effects of microplastics derived from face masks.

Because of the COVID-19 pandemic, used face masks have increasingly littered the environment and are causes for concern since they are commonly made of plastics such as polypropylene. Understanding production of microplastics from face masks is essential for predicting the post COVID-19 pandemic impact on the soil ecosystem. We investigated the generation of nanofibers from meltblown face mask filters (MB filters) and their adverse effects on soil species, particularly the earthworm and springtail. Results of MB filter soil bioassays at a high concentration (1000 mg/kg dry soil) suggest inhibited reproduction and stunted growth in springtails, decreased intracellular esterase activity in earthworm coelomocytes, and inhibited spermatogenesis in male earthworm reproductive tissues. Moreover, it was estimated that generation of nanofibers from microfibers and fragments of MB filters might occur in the soil ecosystem post COVID-19. This study does not oppose the use of face masks but aims to encourage appropriate disposal of the masks. Preservation of human health and the ecosystem should be prioritized even amidst the COVID-19 pandemic.

Air-Filtering Masks for Respiratory Protection from PM2.5 and Pandemic Pathogens.

Air-filtering masks, also known as respirators, protect wearers from inhaling fine particulate matter (PM2.5) in polluted air, as well as airborne pathogens during a pandemic, such as the ongoing COVID-19 pandemic. Fibrous medium, used as the filtration layer, is the most essential component of an air-filtering mask. This article presents an overview of the development of fibrous media for air filtration. We first synthesize the literature on several key factors that affect the filtration performance of fibrous media. We then concentrate on two major techniques for fabricating fibrous media, namely, meltblown and electrospinning. In addition, we underscore the importance of electret filters by reviewing various methods for imparting electrostatic charge on fibrous media. Finally, this article concludes with a perspective on the emerging research opportunities amid the COVID-19 crisis.

Meltblown fabric vs nanofiber membrane, which is better for fabricating personal protective equipments.

The coronavirus disease 2019 (COVID-19) pandemic has led to a great demand on the personal protection products such as reusable masks. As a key raw material for masks, meltblown fabrics play an important role in rejection of aerosols. However, the electrostatic dominated aerosol rejection mechanism of meltblown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation. Herein, novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane (nano cobweb-biomimetic membrane). The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water, 75% alcohol solution, and exposing under ultraviolet (UV) light. After the water immersion test, the filtration efficiency of meltblown mask was decreased to about 79%, while the nanofiber membrane was maintained at 99%. The same phenomenon could be observed after the 75% alcohol treatment, a high filtration efficiency of 99% was maintained in nanofiber membrane, but obvious negative effect was observed in meltblown mask, which decreased to about 50%. In addition, after long-term expose under UV light, no filtration efficiency decrease was observed in nanofiber membrane, which provide a suitable way to disinfect the potential carried virus. This work successfully achieved the daily disinfection and reuse of masks, which effectively alleviate the shortage of masks during this special period.

Enhancing the filtration efficiency and wearing time of disposable surgical masks using TENG technology.

The COVID-19 pandemic has caused an unprecedented human and health crisis. And the shortage of protective equipment, especially the personal protective disposable surgical masks, has been a great challenge. Here, we developed an effective and simple scheme to prolong the lifetime of disposable surgical masks without changing their current structure, which is beneficial to solve the shortage of personal masks. After electrifying the meltblown PP filter by the new-developed single-electrode-based sliding triboelectric nanogenerator (TENG) charge replenishment (NGCR) technology, the processed filter is bipolar charged and has a filtration efficiency beyond 95% for the particulate matter (PM) ranging from PM0.3 to PM10.0. Further, we demonstrate the 80 °C dry heating is an effective decontamination method. This method is compatible with single-electrode-based sliding TENG charge replenishment technology. The 80 °C dry heating and the NGCR technology can make up an effective regeneration procedure for the mask. Even after ten cycles of simulated 4 h wearing process and such regeneration procedure, the filtration efficiency of the disposable surgical masks PM0.3 is still higher than 95%.