Preparation And Properties Investigation Of Electrospun Nanofiber Membranes In Medical Protection

Medical protective materials are one of the important epidemic prevention materials to overcome the COVID-19.Novel coronavirus infects humans through aerosols in the air.Medical protective masks can effectively capture particles and block the transmission of viruses.Polypropylene Melt-blown Nonwovens were used in the traditional medical protective masks deeply dependented on static electricity.The electret charge attenuates with the water vapor generated by breathing,resulting in the rapid decline of the filter efficiency of the mask,which seriously affects the service life.In addition,a large number of discarded masks not only increase the economic burden,but also bring huge environmental pressure.Therefore,electrospun nanofiber membranes were prepared in this paper to enhance the ability of the fibers to mechanically capture particulate matter.Furthermore,the filtration efficiency of the medical protective material was improved,the filtration resistance was reduced,and the service life was prolonged.The effects of spinning process parameters on the filtration performance of polyvinylidene fluoride(PVDF)electrospun nanofiber membranes were investigated.Filtration efficiency,filtration resistance,quality factor,and air permeability were taken as targets,and the analysis of variance method was applied to optimize the spinning process.The results show that the filtration efficiency of PVDF fiber membrane is higher than 95%,and the filtration resistance is between 86.67 and 160 Pa,which meets the protection requirements.The parameters of electrospun had no significant effect on the filtration efficiency,but significantly affected the filtration resistance.Quality factor and air permeability are negatively correlated with filtration resistance.The optimal process is obtained including 15% concentration,27 k V voltage,22 cm TCD,and2.5m L/h flow rate.Then,the PTFE/PVA-PVDF hybrid electrospun nanofiber membrane was prepared by mixing PTFE/PVA fibers and PVDF fibers online in the method of congugate electrospun in order to extend the service life of the mask.Scanning electron microscopy(SEM)and fourier transform infrared spectroscopy(FTIR)were used to characterize the morphology and material structure of the fiber membranes.The thermal stability,triboelectric properties,initial filtration efficiency,particulate filtration fatigue and air and moisture permeability comfort of the fiber membrane were tested and analyzed.The results show that under the condition of electrostatic elimination,the fiber membrane can convert the mechanical energy generated by respiration into electrical energy through triboelectric effect,and restore the electrostatic filtering effect.The fiber membrane maintains high efficiency and low resistance after filtering 24 times for 144 minutes and holding about 120 mg Na Cl aerosol.It will prolong the service life of masks and greatly reduce the economic expenditure and environmental pressure caused by mask replacement.Finally,the silver nanoparticle-doped PVDF nanofiber/nets was prepared in an inorganic/organic hybrid manner to endow the protective fiber membrane with antibacterial function.X-ray diffraction(XRD),fourier transform infrared spectroscopy(FTIR),energy dispersive spectroscopy(EDS)and X-ray photoelectron spectroscopy(XPS)were used to characterize the composition and structure of the fiber membrane.The thermal performance,filtration fatigue performance,antibacterial rate and bacterial filtration efficiency of the fiber membrane were measured.The results showed that silver nanoparticles(AgNPs)were uniformly decorated on the surface of PVDF nanofiber/nets.After 24 times of particle circulating filtration,the resistance exceeds343.2Pa,reaching the maximum value required for protection.The antibacterial rate of fiber membrane against Staphylococcus aureus and Escherichia coli exceeded 99%.The bacterial filtration efficiency(BFE)is higher than 96.16%,among which AgNPs/PVDF-2 has the excellent performance.The one-step preparation of AgNPs/PVDF fiber membrane not only greatly shortens the process,but also has broad application prospects in the medical field with its antibacterial functionality.