Characterization of Industrial Filter Materials for Improved Filter Medium Selection

Filter fabrics for solid/liquid separation have been analyzed and characterized in order to provide additional knowledge about said fabrics. Three different fabrics, AINO, MITO and ASKO have been studied in this thesis as well as used samples of the AINO and MITO fabrics. According to the manufacturer, AINO and MITO were virgin polypropylene while ASKO had an abrasion resistant coating. Further, a literature research has been conducted with the aim to find new developments within the filter media business and to present improvement ideas for the provided fabrics. The analyses showed that AINO does not consist of merely virgin PP. Further tests showed that the warp yarn likely contains an additive consisting of PP-grafted maleic acid. Whereas MITO only contains PP, as the manufacturer said, apart from trace amounts of for example calcium that could be part of an acid scavenger such as calcium stearate. ASKOs coating is likely a polyester, and the coating is present in very small quantities. Other analyses, including mechanical tests and TGA, showed that both AINO and MITO are suitable for high temperature applications (at least up to 60°C), but ASKO is not. The mechanical tests also showed that the used AINO fabric has a significantly higher tensile strength due to orientation and adhering of the fibers due to the filtration process. MITO did not show any significant change after utilization as a filter in neither mechanical strength nor thermal degradation. The literature research covers the market trends and the direction of inventions. Coatings, nanoparticles and materials like PVDF are of interest, and so are nonwovens. Much of the most recent research concerns nonwovens, as they are both easier to produce and to dispose of. So far, however, the nonwoven fabrics cannot compete with the woven fabrics in such harsh filtration environments as solid/liquid filtration