Production of Filter Material from Polypropylene/Copolyamide Blend by Material Extrusion-Based Additive...

The effect of technological conditions of the process and zirconia (ZrO₂) nanoparticles on the properties of fine-fibrous filter materials (FMs) obtained by matrix polymer extraction from a microfibrillar composite formed using the material extrusion-based additive manufacturing method from a polypropylene (PP)/copolyamide blend is studied. Different processing schemes were used for obtaining filaments for material extrusion: scheme I-the use of a single-screw extruder at the stage of compounding; scheme II-the use of a single-screw extruder at the stage of compounding and orientational stretching in the course of strand formation; scheme III-the use of a twin-screw extruder at the stage of compounding, scheme IV-the addition of ZrO₂ nanoparticles and use of a twin-screw extruder. It has been shown the possibility of reducing the diameters of the formed in situ PP microfibrils by using the twin-screw extruder, as well as additional orientation drawing. The introduction into the melt of ZrO₂ nanoparticles provides further improvement of the microstructure-the average diameter of the microfibrils is reduced by 1.4 times compared with the initial blend. Developed FMs are characterized by high efficiency of air purification from solid particles with a size of 0.3 μm. At the same time, the use of nanoadditives is the most effective-a two-layer FM with nanoparticles provides cleaning efficiency at the level of four- to six-layer materials without filler.