| A series of human-related activities such as transportation,industrial production and thermal power generation continue to emit a large number of air pollutants,which has become a major environmental problem hindering the sustainable development of today’s society and affecting people’s healthy life.With the promulgation and implementation of a series of strict environmental protection laws and regulations,the application field of air filtration equipment and materials has had tremendous development in the past 10 years and continues to accelerate the development in technical performance and economic benefits.As the core of filtration equipment,the research and development of filtration material has also received unprecedented attention,among which fiber air filter has become the main filter material,while non-woven material with its superior performance has become the most important.Polyphenylene sulfide(PPS)non-woven fabrics are one of the most chemically resistant and cost-effective materials for removing pollutants from power plant exhaust gases.However,numerous studies have shown that when PPS is exposed to gaseous components,such as oxygen,NO and NO2 at high temperatures,the mechanical properties of PPS fibers are reduced,the service life is reduced,and the frequent replacement of filter bags increases enterprise costs.In addition,due to the inherent defects of traditional non-woven fabric,its filtering accuracy of ultrafine particles is not high due to the coarse fiber diameter,which seriously restricts its development in the field of air filtration.In the first part of this thesis,benzoxazine was selected as a heat-resistant and oxidationresistant cross-linked polymer precursor,and the surface modification of commercial conventional polyphenylene sulfide fibers was carried out by impregnation coating method.The coating material forms a protective film of polybenzoxazine after adhesion and crosslinking curing on the fiber surface.In this study,the heat resistance,chemical corrosion resistance and wettability of the modified fiber were studied,and it was found that the coating improved the heat resistance and oxidation resistance of the fiber substrate,and enhanced its structural stability in harsh environment.In addition,the polybenzoxazine coating system helps to construct the surface of hydrophobic fibers and fabrics,reducing the influence of water vapor and acid gas on PPS fibers.At the same time,the application of uniform nano-coating enhances the pore structure stability of PPS fiber non-woven fabric,and further improves the mechanical properties of filtration material and the ability to capture particles in the air.In addition,the continuous process of modification of high temperature resistant fiber surface coating proposed in this paper is suitable for the continuous production process of industrial non-woven fabrics.This technology is expected to achieve industrial application at controllable cost,giving PPS fiber and its fabric(nonfabric)service life at higher ambient temperatures.In the second part of this paper,PPS fiber composite filter material is prepared by electrostatic spinning technology to further improve the filtration efficiency of fine particles.Firstly,polyether-acrylamide(PEI)and poly(m-phthaloyl-m-phenylenediamine)fiber(PMIA),which have excellent thermal stability and chemical resistance,were selected to prepare a PEI/PMIA multiscale fiber membrane with self-supporting three-dimensional mesh nanofiber/spider structure by adjusting the polymer blending and spinning parameters.The forming mechanism,heat resistance and chemical corrosion resistance of the cobweb were studied.It was found that the fiber membrane had excellent heat stability,chemical corrosion resistance and self-cleaning performance.The relationship between the structure and air filtration performance was explored.The fiber membrane prepared in this project has multi-scale fiber structure(fiber with diameter of 600 nm + spider with diameter of 50 nm)and smaller pore structure,thus possessing excellent particle filtration efficiency and extremely low piezo resistibility.The filtration performance of fiber membrane can be further improved by adding metal organic framework material ZIF-8 into the fiber system.Finally,the surface modification of PPS fiber and the composite of PEI/PMIA@ZIF-8 fiber membrane were realized by combining the modification process of PBA coating and the hot pressing process,and the PEI/PMIA/PPS micro/nano composite filter material with multiscale structure was prepared,which can effectively improve the filtration capacity of PPS non-woven fabric for small particles.The bonding fastness between non-woven fabric and fiber film is good.The composite filter material prepared in this paper has a broad application prospect in the field of high-performance air filter material in complex environment in the future. |
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