Preparation Of PMIA/PAN Blend Nanofiber Membrane For Air Filtration And Study On Its High Temperature Resistance

With the continuous acceleration of our country’s industrialization process,the problem of environmental pollution should not be underestimated.Some small and medium-sized power stations,paper mills,brick factories,etc.often produce a large amount of high-temperature dustcontaining waste gas in daily production,and improper treatment will pose a huge threat to the environment and human health.The existing high temperature gas dust removal technology and some high temperature resistant filter materials have some shortcomings in actual use,especially the filtration efficiency for extremely small particles needs to be improved.Electrospinning technology can effectively prepare continuous nanofibers.Combining high-temperature resistant materials with electrostatic spinning technology can give high-temperature resistant materials the small size effect of nanofibers.It is expected to prepare a new kind of air filter material which performs high-precision filtration,excellent mechanical properties and high temperature resistance.This project selects polyacrylonitrile(PAN)with high spinnability and high-performance fiber meta-aramid(PMIA),and prepares PMIA/PAN nanofiber membranes through solution blending modification to explore their value on high-temperature filtration.First,prepare PAN and PMIA nanofiber membranes with different mass fractions,determine the best mass fractions of each,and explore their high temperature resistance through heat treatment.The results showed that the optimal mass fraction of PAN solution is 10%,and the filtration efficiency of the nanofiber membrane after heat treatment had increased from 97.35% to 99.75%.As the heat treatment temperature rises,the filtration efficiency had been stable above 99%,which proved it has a relatively stable filtration efficiency under high temperature conditions.Heat treatment increased the breaking strength of PAN nanofiber membranes,while also reducing the breaking elongation.The best mass fraction of PMIA solution is 11%.After heat treatment,the filtration efficiency remained above 99.9%.The breaking strength gradually decreases.The breaking elongation first increases and then decreases.It is preliminarily proved that the two materials still maintain excellent filtration efficiency and has better high temperature resistance at200 ℃.Subsequently,the 11-x series PMIA/PAN nanofiber membranes were prepared by blending11wt% PMIA solution and PAN solutions of different mass fractions in equal proportions by mass.The results showed that: with the mass fraction of PAN solution in the blending part of the two solutions,the average diameter of the blended nanofiber membrane increases,the CV value gradually decreases,the breaking strength first decreases and then increases,while the breaking elongation gradually increases.After a comprehensive comparison,it is found that 11-12PMIA/PAN nanofiber membrane has the best mechanical properties.The filtration test results showed that the filtration efficiency first increases and then decreases,and the filtration resistance first decreases and then increases.Finally,the best combination of PMIA/PAN is selected as 11-12 to optimize its performance.The optimized preparation of PMIA/PAN nanofiber membranes was achieved by adjusting the mass ratio of 11wt% PMIA solution and 12wt% PAN solution.The test showed that the relationship curve between the viscosity of the blending system and the blending ratio is non-linear and non-"S",indicating that PMIA and PAN are partially compatible and have greater application value.The mechanical properties of PMIA/PAN nanofiber membranes with different mass ratios were tested,it is found that when PAN and PMIA blended with equal mass ratio,the nanofiber membranes had the lowest breaking strength and the largest elongation;when the blended mass ratio became nonequal,the breaking strength of it is increased,and the elongation is decreased.The mechanical properties of nanofiber membranes are the best when the blending mass ratio is 9:1.Testing the filtration performance found that with the gradual increase of the blending mass ratio,the filtration efficiency and filtration resistance of the nanofiber membrane showed a roughly similar trend.When the blending mass ratio was 9:1,its filtration efficiency and filtration resistance are both the highest,respectively 92.69% and 44.59 Pa,and finally considering the mechanical properties and filtration performance,the best blending mass ratio is considered to be 9:1.Finally,the PMIA/PAN nanofiber membrane with a blending mass ratio of 9:1 was heat-treated to explore its high temperature resistance.The results showed that the color and morphology of PMIA/PAN nanofiber membranes have not changed after heat treatment,and the PAN nanofiber membranes after heat treatment have turned yellow and become brittle under the same conditions,and tend to be carbonized.After testing the mechanical properties of PMIA/PAN nanofiber membranes after heat treatment,it was found that the breaking strength decreased slightly and the elongation at break increased significantly.Moreover,the filtration test found that the PMIA/PAN nanofiber membranes with a blend mass ratio of 9:1,the filtration performance is always maintained above 99%,which proves that the performance of PMIA/PAN blended nanofiber membrane exceeds that of single-component PAN nanofiber membrane,and it has relatively excellent mechanical properties,stable filtration performance,and durability at high temperatures,which provides a new research direction and reference method for the preparation of high-efficiency and clean hightemperature resistant filter materials.