| The rapid development of industry has brought unavoidable pollution to the environment.The exhaust gas emitted by industrial production has the characteristics of high temperature and complex composition,and ordinary air filter materials cannot meet the requirements.Therefore,the research of high temperature resistant filter materials for filtering industrial exhaust gas is widely accepted.attention.There are stable benzene rings and amide rings in the polyimide(PI)macromolecular chain,which has very excellent thermodynamic properties and is often used to filter high-temperature exhaust gas.Electrostatic spinning nanofibers have great development prospects in the field of filtration due to their small diameter,high porosity and large specific surface area.Combining the advantages of the two,this subject uses a self-assembled needleless electrospinning device to adjust and configure different spinning liquid parameters to achieve the industrial preparation of PI high-temperature filter media for industrial waste gas treatment.And the performance of the nanofibers before and after the biamination treatment.In addition,in order to enhance the adhesion between the PI nano-filter material and the glass fiber substrate,improve the coating fastness of the high-temperature filter material,and design hightemperature filter materials with three different structures of A,B,and C,through electrostatic blending of low melting point Polyacrylonitrile(PAN)nanofibers are then hot-rolled and hot-melt bonded to enhance the film fastness of the composite filter.First of all,in order to solve the problem of low production efficiency of traditional electrospinning and the industrial batch preparation of polyimide nanofibers,the self-assembled disc-shaped nozzle needleless electrospinning device of this research group was used to try different spinning solution configuration methods.When the concentration of polyamic acid(PAA)is 25%,the spinning voltage is 54 kv,and the spinning receiving distance is 20 cm,the average diameter is 189 nm,the filtration efficiency is 99.908%,and the filtration resistance is only 130.72 Pa.Filter material for filtration.Secondly,the performance of PAA fiber membrane and PI nanofiber membrane are compared,and the effect of imidization treatment on the performance of fiber membrane is explored.After the imidization treatment,the average fiber diameter becomes thinner,the average pore size becomes larger,and the filtration efficiency drops by 0.5%.In addition,the fiber becomes more brittle after heat treatment,and the breaking strength and breaking elongation both decrease significantly.However,this experiment studied the filter material for high-temperature exhaust gas.The long-term use temperature is about 260 ?.The thermal loss of PAA before 260 ? is greater than 20%.The thermal loss of PI nanofibers obtained after heat treatment at 260 ? is less than 260 ?.1%,with good thermal stability.Finally,in order to enhance the adhesion between the filter material and the protective substrate,high-temperature filter materials with three different structures A,B,and C are designed,and the lowmelting polyacrylonitrile PAN nanofibers are electrostatically blended,and then hot-rolled In combination and hot-melt bonding,the low-melting PAN nanofibers are melted and used as an adhesive to bond the glass fiber machine base fabric and PI nanofibers to enhance the film fastness of the composite filter material.The filtration performance of the three composite filter materials A,B and C is very good.The filtration efficiency before heat treatment can reach 99.994%,99.986% and 99.842% respectively,and the filtration resistances are 425.32 Pa,882.98 Pa and 282.24 Pa respectively.After hot rolling,the film fastness of B and C filter materials increased from 0 to 2171.2Pa and 4621.2Pa,but the hot rolling process destroyed the structure of nanofiber membranes,and the filtration efficiency of the three filter materials of A,B,and C was from 99.994 respectively.%,99.986%,99.842% decreased to 77.8%,72.8%,84.8%.The filtration efficiency of the composite filter material is greatly reduced.After the hot-melt bonding treatment,the fastness of the coating materials of the two filter materials B and C was increased from 0 to 730 Pa and 962.5Pa,respectively.And while the fastness of the coating is improved,the filtration performance of B and C filter materials is guaranteed.The filtration efficiency of B-type filter material is changed from 99.986% and 882.98 Pa to 99.988% and 989.8Pa.The filtration of C-type filter material The effective filter resistance changed from 99.842% and 282.24 Pa to 99.968% and 503.72 Pa.Hot-melt bonding can improve the fastness of the filter material coating while ensuring the high-efficiency filtration performance of the filter material,which is a better way to enhance the film fastness. |
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