Processing-structure-property relationships of novel fibrous filters produced by a melt-process

Fibrous filters were produced using a novel melt-based co-extrusion and two-dimensional multiplication technology combined with a delamination technique using high-pressure water jets. The fibrous filters produced comprising continuous and rectangular polypropylene (PP)/polyamide 6 (PA6) micro/nano-fibers have structural integrity and uniform fiber distribution. The orientation procedure greatly improves the PP/PA6 crystal orientation, decreases the fiber sizes, and enhances their mechanical performance as filters. These filters have large surface area, micron-sized pores, and high porosity (similar to 90 %), which are desirable for microfiltration applications. Structural and property analysis was performed on the PP/PA6 fibrous filters produced from varying number of plies of the composite tapes with different draw ratios and fiber width-to-thickness ratios. It was found that increasing the tape draw ratio improves the surface area and porosity of the filters, and decreases its pore size. Using more plies generates decreased filter pore size and unaffected porosity. Filters comprising fibers with higher width-to-thickness ratio have higher surface area, smaller pore size, and unchanged porosity. This melt-based, versatile technology is applicable to any melt-processable polymers to produce fibrous filters having tunable properties for various filtration applications.