A Study On Filtration Performance Of Nonwoven Air Filtering Material

Due to the aggravation of the environmental pollution in our country, more and more big cities occur the dust storm and haze weather, threatening people’s health tremendously. Whether in the aspect of industrial environmental protection or in the internal space of household and automobile, people are increasing their expectation of air quality and a series of strict environment protection laws and regulations are being issued and implemented, making the air filtering materials develop fastest in the market of filtering materials in the global world. With each country paying more and more emphasize on environmental protection and the developing requirement of high technology industry, the application fields of air filtering devices are enlarging. As the core part of air filtering devices, air filtering materials have gained unprecedented attention, in which the nonwoven materials have gained more than any other materials because of their superior performances.According to the situation mentioned above, this research, firstly, based on the former people’s research, is to further deepen the understanding of the filtration mechanisms by collecting and sorting out the existing theories. Meanwhile, to find the better way to apply the filtering theory, some theoretical calculation and qualitative and quantitative analysis have been made by using the Matlab program; the factors such as aerosol particle size, fiber diameter, filling rate, thickness, filtration rate and aerosol concentration, which influence the filtering performance investigate, are investigated; the ways they influence the filtering performance are revealed.Secondly, by using the electron scanning microscope and PMI pore diameter tester, the structures of various nonwoven materials are tested in order to explore the influence on filtration performance of each structure factor. According to the structure parameters tested, calculations are made to predict the nonwoven materials’ filtration performance. Lastly, the materials’filtration performance are tested in the TSI Model8130by adopting two kinds of aerosol particle, NaCl and Paraffin Oil.Through the theoretical analysis, we can know the relationship of various structure parameters with the filtration efficiency and filtration resistance. Through the experimental research, we can figure out the rules that filtration performance changes with each structure factor. By comparing the theoretical analysis and experimental researching result, we can find out the differences and similarities between them and verify the filtering theory’s instructive function to the practical application.Filtering process has two stages, which are stable filtrating period and unstable filtrating period. Under the assumption of stable filtrating, the theoretical analysis and experimental research have been made. By testing the dust holding capacity and testing the relationship of filtration efficiency and filtration resistance changing with the time, the change process of filtration performance during the unstable period is discussed.Because the general nonwoven material without any treatment doesn’t have a good filtration performance, say no more than40%. Increasing the thickness and improving the filling rate can improve the filtration efficiency, but they also increase the filtration resistance largely and thus bring in huge energy consumption. Electrets treatment is an effective method to improve the filtration efficiency and lower the resistance. This topic, through discussing the influence of electrets time, electrets distance, electrets voltage and heat treatment temperature on electrets effect, find out the optimum technological parameter. Under this optimum technological parameter, the nonwoven materials were electrets treated and then the filtration performance was tested. In consideration of the stability and usage occasion of the filtering material with electrets treatment, filtration efficiency, filtration rate, resistance, dust holding capacity and attenuating property are investigated, and the performance with or without the electrets treatment is compared, offering the reference to improve the performance and promote the application of electrets filtering materials.The research above lays a foundation for the development and application of nonwoven material in the air filtering field, and is of great importance to solve the air pollution and haze weather occurred frequently and control the inhalable particle concentration and protect the people’s health.