超低阻呼吸防护用聚乳酸纳米纤维膜制备及长效过滤性能

Preparation and long-term filtration performance of PLA-based nanofibrous membrane filters for ultra low-resistance respiratory protection

  • 摘要: 长期暴露于大气环境中高浓度的细颗粒物(PM2.5)会对人类的长期健康效应产生消极影响,传统空气过滤材料难以兼顾高效、低阻的防护效果,且不可降解,不仅加剧全球塑料污染,还易产生更强的微塑料危害。为此,制备了一种具有空气滑移效应、自供能且可生物降解的纳米纤维膜,以保障长效、低阻呼吸防护。提出两步水热法制备平均粒径49.6 nm、易分散的BaTiO3电介质,同时利用“静电纺丝−静电喷雾”法将BTO纳米颗粒(BTO NPs)原位嵌入PLA纤维膜,利用BTO NPs的摩擦电效应和尺寸效应同步调控纤维膜的过滤效率和空气阻力。通过控制喷雾悬浮液中BTO NPs的浓度,探讨其与PLA/BTO纤维膜电活性、过滤性能和力学性能之间的关系。微观表征和性能测试结果表明:PLA/BTO纤维膜具有优异的电活性、过滤性能及力学性能。PLA/BTO纤维膜表面电势可高达5.9 kV,介电常数达1.20 F/m,平均输出电压高达12.4 V;得益于增强的空气分子滑移效应和电活性,PLA/BTO10纤维膜在显著降低空气阻力(低至20 Pa)的同时,对PM0.3过滤效率提升了7.78%~9.05%,对PM2.5过滤效率提升了2.90%~13.19%,即使在85 L/min高测试流量下仍能保证高达97.25%的PM2.5过滤效率;同时,PLA/BTO纤维膜拉伸强度增幅高达60%(拉伸强度22.5 MPa),断裂伸长率增幅高达68%(断裂伸长率25%),而断裂韧性最高可提升1.3倍(断裂韧性3.6 MJ/m3)。因此,提出的兼具长效、低阻过滤且可降解纤维膜在呼吸防护领域具有广阔的应用前景,也为缓解废弃口罩加剧的塑料污染现状提供了一种新思路。

     

    Abstract: Long-term exposure to high concentrations of fine particulate matter (PM2.5) in the atmosphere has negative impact on the long-term health effect of human beings. Traditional air filtration materials are difficult to take into account the high-efficiency and low-resistance protection, and are non-degradable, which not only aggravates global plastic pollution, but also tends to cause stronger microplastics hazards. To solve the problems above-mentioned, self-powered and biodegradable nanofibrous membranes with air slip effect are developed to achieve a long-term and low-resistance respiratory protection. A two-step hydrothermal method is proposed to prepare the easily dispersed BTO dielectric with an average particle size of 49.6 nm, then the BTO nanoparticles (BTO NPs) are embedded into the PLA nanofibrous membranes by a combined “electrospinning‒electrospray” strategy. The frictional electricity effect and size effect of BTO NPs are utilized to simultaneously regulate the filtration efficiency and resistance of nanofibrous membranes. By controlling the concentration of BTO NPs in spraying suspension, the relationship between it and electroactivity, filtration properties and mechanical properties of PLA/BTO nanofibrous membranes is investigated. Microstructure characterization and performance testing show that the PLA/BTO nanofibrous membranes have excellent electroactivity, filtration properties and mechanical properties. The surface potential of PLA/BTO nanofibrous membranes is up to 5.9 kV, the dielectric constant is up to 1.20 F/m, and the average output voltage is up to 12.4 V. Benefiting from the enhanced slip effect and increased electroactivity, the electrospun-electrosprayed PLA/BTO10 nanofibrous membrane could significantly reduce air resistance (as low as 20 Pa), while improving the filtration efficiency of PM0.3 by 7.78%−9.05% and the filtration efficiency of PM2.5 by 2.90%−13.19%. Even at the high airflow velocity of 85 L/min, the filtration efficiency of PM2.5 still achieves as high as 97.25%. At the same time, the increase of tensile strength of PLA/BTO nanofibrous membranes is up to 60% (22.5 MPa), the increase of elongation at break is up to 68% (25%), and the fracture toughness increases by 1.3 times (3.6 MJ/m3). Therefore, the proposed degradable PLA/BTO nanofibrous membrane filters with long-term and low-resistance filtration properties have some broad application prospects in the field of respiratory protection, and also provide a new approach to alleviate the plastic pollution exacerbated by discarded masks.

     

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