BACTERIOSTATIC POLYPROPYLENE NONWOVENS FOR MEDICAL FACE MASKS
This paper investigates imparting a bacteriostatic effect to polypropylene nonwovens used in manufacturing disposable medical face masks, by translating them into the electret state. The study objects were polypropylene webs with a density of 20 g/m<sup>2</sup>, obtained by the spunbond method (SS20). The electret state was created in the field of corona discharge. It is shown that the level of electret potential difference (U<sub>epd </sub>= 0.95 kV), surface potential (V<sub>e</sub> = 0.12 kV), effective surface charge density (s<sub>ef</sub> = 0.07 mC/m<sup>2</sup>), and electric field strength (Е = 7.63 kV/m) of a polypropylene nonwoven allows it to be used as an electret material. Microorganisms that cause various diseases, such as Staphylococcus aureus and Staphylococcus epidermidis, were microbiologically tested for their stability against the materials developed, using the disk diffusion method on Muller-Hinton agar. It was found that the test materials did not provide any bactericidal effect on these cultures. When electret polypropylene non-woven webs were placed on a nutrient medium with a bacterial suspension, they showed clear edges of the zone of inhibition of the growth of microorganisms, growth of isolated single colonies inside the zone. This indicates the bacteriostatic effect of electret material on staphylococcus. Conventional (non-electret) polypropylene non-woven webs don’t have a similar effect on these bacteria. It turned out that if for standard webs the breathability is 3,840 dm<sup>3</sup>/m<sup>2</sup>×s, then for electret samples is 3,800 dm<sup>3</sup> / m<sup>2</sup>•s. A slight decrease in values is explained through the oxidative processes occurring during processing the polypropylene in a corona discharge, that is, through the appearance of carbonyl, carboxyl, hydroxyl, and other oxygen-containing groups in its macromolecules. The ability of the electret state of polypropylene nonwovens to affect adversely the development of bacteria Staphylococcus aureus and Staphylococcus epidermidis enabled using disposable bacteriostatic electret medical face masks to prevent the outbreak of some airborne transmitted diseases