Study On Preparation And Properties Of Composite Filter Material With Gradient Structure

With the rapid development of industry, the increasingly serious air pollution is a great threat to people’s health. Therefore, it is urgent to improve air quality and performance of air filter material. Electrospun nanofiber felt with fine fiber diameter, strong adsorption ability is widely used in the field of air filtration. When thickness of electrospun nanofiber felt increases, filtration efficiency and pressure drop of electrospun nanofiber felt increase. When it filters aerosol particles, electrospun nanofiber felt is easy to block. When it filters aerosol particles, filter material made of micron-sized fiber with low pressure drop, stable structure is not easy to block. Therefore, in the practical application, nanofibers are electrospun on the base cloth. In addition, filter material with gradient structure guarantees that filtration efficiency of filter material is high and its pressure drop is low. In this study, composite filter material with polyacrylonitrile as raw material, polypropylene melt-blown nonwoven fabric as base cloth, is prepared by introducing concept of gradient. In this way, it can not only make up for inadequacy of electrospun nanofiber felt, also improve filtration performance of filter material. The main contents include the following several aspects:(1) Research on process of electrospun PAN fibers. The morphology of electrospun PAN fibers and filtration efficiency of electrospun PAN nanofiber felt/PP melt-blown fabric composite filter material were tested to research the relationship of them with the concentration of spinning solution, applied voltage, received distance. The results show that concentration of spinning solution and applied voltage have more significant effect on them than received distance. With the increase of concentration of spinning solution, diameter of PAN fibers and filtration efficiency of composite filter material gradually increase. With the increase of applied voltage, diameter of PAN fibers gradually decreases, filtration efficiency of composite filter material gradually increases. In addition, filtering performance of PAN nanofiber felt/PP melt-blown fabric composite filter material was tested to research the relationship of it with the electrospinning time. The results show that under the spinning process of 12% concentration of spinning solution,15kV applied voltage,165mm received distance, electrospinning time 60min, composite filter material is prepared. Filtering efficiency of composite filter material measures up to standard at level 2. Pressure drop is up to standard.(2) The preparation of composite filter material with gradient structure and electrospun PAN nanofiber felt/PP melt-blown fabric composite filter material. At the same spinning process of applied voltage and received distance, composite filter material with pore size gradient was prepared by changing concentration of spinning solution of each layer. Accordingly, electrospun PAN nanofiber felt/PP melt-blown fabric composite filter materials were prepared by changing concentration of spinning solution in single factor method. At the same spinning process of concentration of spinning solution and received distance, composite filter material with pore size gradient was prepared by changing applied voltage of each layer. Accordingly, electrospun PAN nanofiber felt/PP melt-blown fabric composite filter materials were prepared by changing applied voltage in single factor method.(3) The properties of composite filter material with gradient structure and electrospun PAN nanofiber felt/PP melt-blown fabric composite filter material. The results show that when eletrospinning time is 22.5 min, composite filter material with pore size gradient have higher filtration efficiency and lower pressure drop than according composite filter material. Filtering efficiency of them measures up to standard at level 2. When eletrospinning time is 45 min and 60min, composite filter material with pore size gradient have higher filtration efficiency and pressure drop than according composite filter material.This paper carried out a study and analysis from process of electrospun PAN fibers to preparation and characterization of composite filter material with gradient structure, according PAN nanofiber felt/PP melt-blown fabric composite filter material, and relationship of their structure with filtering performance, which provide a theoretical foundation and basis for filter material to obtain high filtration efficiency and low pressure drop.