| With the improvement of industrialization,air pollution has gradually become the focus of public attention.Air pollution particles mainly include salt aerosol particles and oil aerosol particles.These particles are harmful to human health and the environment.Therefore,it is necessary to filter and intercept them with air filter materials.Oily particles are fluid and will be affected by the performance of the filter material during filtration.Electrospinning Micro-Nanofibers have the advantages of fine diameter and high porosity,which are very suitable for making high-performance air filter materials.Therefore,the hydrophobic and oil repellent micro nano fiber filter material was prepared,the gradient structure was designed to improve its filtration performance,and its mechanical properties were enhanced by compounding with nonwovens to prepare highperformance micro nano fiber air filter material.Firstly,in order to reduce the surface energy of materials,fluorinated polyurethane(FPU)was introduced into polyacrylonitrile(Pan)fiber membrane to prepare pan / FPU micro nano fiber membrane and characterize its properties.The results show that with the increase of FPU addition,the surface energy decreases,the diameter increases,the roughness increases,the pore size increases,the filtration efficiency and resistance decrease,and the fracture strength decreases.When the mass fraction of pan is 12% and the addition amount of FPU is 20%,the surface energy of fiber membrane is the lowest and the hydrophobic and oil repellent performance is the best.Secondly,because the introduction of FPU improves the hydrophobic and oil repellent performance of fiber membrane and reduces the filtration performance,in order to improve the filtration efficiency and reduce the filtration resistance as much as possible,a double-layer gradient structure is designed.The filtration performance of single-layer uniform and double-layer gradient micro nano fiber membrane is simulated by COMSOL software.It is found that the double-layer gradient structure can effectively reduce the filtration resistance while improving the filtration efficiency,and when the air flows from the coarse diameter side to the fine diameter side,its filtration efficiency is higher and the filtration resistance is lower.In order to explore the influence of the thickness ratio of coarse and fine fiber layers in the double-layer gradient micro nano fiber membrane on the filtration effect and the best thickness ratio,the gradient micro nano fiber membrane with the same total thickness and the thickness ratio of fine and coarse fiber layers of 1:1,1:2,1:3,1:4 and 1:5 was prepared.The results show that with the increase of the thickness of the coarse diameter layer,the breaking strength,pore size,permeability,filtration efficiency and filtration resistance of the gradient structure fiber membrane decrease.When the thickness ratio of fine and coarse fiber layer is 1:3,the comprehensive filtration effect of fiber membrane is the best.At this time,the filtration efficiency of salt particles is 99.84% and the filtration resistance is 163.7PA;The filtration efficiency of oily particles is 99.88% and the filtration resistance is 168 PA.Finally,in order to improve the strength of the prepared double-layer gradient micro-nanofiber membrane,the ES fiber non-woven fabric was composited with the double-layer gradient micronanofiber membrane by hot air bonding.The study found that with the prolongation of treatment time,the peel strength and breaking strength of the composite film gradually increased,and the elongation at break decreased gradually.Since the bonding point will cause a certain blockage to the fiber membrane,with the extension of the hot air treatment time,the air permeability of the fiber membrane decreases slightly,and the filtration resistance gradually increases.More than 99.8%.Considering the performance test results of the composite membrane,the optimal hot air treatment time is 4 min. |
PDF Full Text Request