PRODUCTION OF POLYPROPYLENE MESHES USING ADDITIVE TECHNOLOGIES AND STUDY OF THEIR STRUCTURE AND PROPERTIES

In this work, polypropylene meshes were obtained by additive technology and their structure and properties were studied. The grids were printed on a Creality K1 MAX 3D printer with a 0.2 mm nozzle diameter and with OrcaSlicer software. It turned out that when printing small-thickness polypropylene meshes, certain difficulties arise (the printing process is more complicated, the level of adhesion to the printing table and interlayer adhesion is lower, resulting in various defects). As a result of optimizing the printing parameters, it was found that the printing speed in the range of 30-60 mm/s allows for high production speeds while maintaining excellent adhesion between the layers and minimizing the risk of deformation. Printing with a polymer layer height of 0.2 mm in one layer has become optimal. It is shown that the structural parameters of the obtained meshes differ from the specified ones - the average thickness of the meshes, determined using a micrometer, was 0.29 mm, the cell size was 1.2-1.4 mm, and the thickness of the filaments was heterogeneous and amounted to 0.22-0.27 mm. The mechanical properties of the mesh material were judged by the tangential stiffness calculated for the case of medium bending according to the classification of H.M. Mushtari and determined on a special device of the experimental installation using a substrate of thin polypropylene film 0.04 mm thick to ensure tightness in the loading system of the test samples. The tangential stiffness of the resulting polypropylene mesh was 4.18-5.91 kg/cm. Fragments of the test from the beginning to the rupture of the grid are presented - types of the dome formed at various loading pressures. It has been found that polypropylene meshes printed on a 3D printer are characterized by spontaneous polarizability, that is, they are characterized by the presence of a polarization charge in the filaments that persists for a long time. The values of the electret properties of polypropylene meshes on the 20th day of storage (during charge stabilization) were as follows: surface potential - 0.10 kV, effective surface charge density - 0.056 µl/m2, electric field strength - 6.7 kV/m. This allows them to be used, for example, as electret filters, which are known to have a high degree of purification.