Abstract:

Objective In recent years, the emergence of the COVID-19 epidemic and airborne particulate pollution has led to a surge in the consumption of face masks. Masks are usually made of non-biodegradable petroleum-derived non-woven materials, which increase global plastic pollution and put great pressure on the human environment, hygiene, and health promotion. Using biodegradable materials to prepare masks can effectively alleviate the pressure of discarded masks on the ecological environment. Therefore, the development of biodegradable masks is significant in reducing environmental pollution.

Method Biodegradable PLA, used as the material, was combined with melt-blown spinning and electrostatic spinning technologies to prepare a bilayer composite micro-and nano-structured fiber membrane as the filter core layer of the mask, and integrated the mask accessories to make a complete biodegradable PLA mask. The microscopic morphology of the bilayer structure and the filter core layer were analyzed, and the protective performance, thermal comfort management, adaptability, and degradation performance of PLA masks were comprehensively evaluated by comparing them with commercially available masks.

Results A double-layer composite structure of PLA melt-blown membrane with an average fiber diameter of 8 μm as a base fabric and a nanofiber membrane with an average diameter of 204 nm as a filter core layer was prepared by combining melt-blown spinning and electrostatic spinning techniques. The results showed that the fiber surface of the composite fiber membrane of the bilayer structure was smooth and continuous, and the fiber morphology was also good. The protective performance of the complete PLA mask designed and prepared according to the three-dimensional facial model was studied and analyzed, and the results showed that the expiratory and inspiratory resistance of the PLA mask was 83 Pa and 79 Pa, respectively, providing a more balanced breathing resistance performance. The filtration efficiency of the PLA mask was 95.8%, and the layered interception mechanism of the double-layer structure makes the PLA mask perform well in filtration performance. The thermal comfort management performance of the mask was analyzed by infrared thermography, and the results showed that the surface temperature of the PLA mask changed from green to yellow, which showed a higher temperature and good thermal comfort management performance. The fit performance of the PLA mask was examined by quantitative fit, and the total fit factor of the optimized PLA mask was 69.57, demonstrating good fit comfort. The degradability of the PLA masks was verified through accelerated degradation experiments. The PLA mask showed a mass loss of up to 50% in 40 days, especially the nanofiber membrane of the filtration layer which completely degraded in only 8 days, a characteristic that not only confirms the biodegradability of the PLA mask, but also shows its rapid degradation, an advantage that helps to alleviate the pressure on the environment caused by discarded masks. By comparing the PLA masks with commercially available disposable and N95 masks, the PLA masks are well balanced in terms of overall basic performance and have good biodegradability, indicating that the PLA masks are a promising product for medical protection.

Conclusion A PLA micro- and nano-filtration core layer with a bilayer composite structure was successfully prepared by combining melt-blown spinning and electrostatic spinning techniques. According to the three-dimensional facial model, the mask layout was prepared, and a complete biodegradable PLA mask was prepared through integrated accessories according to the layout drawing, which was simple to operate. By comparing with commercially available masks, this biodegradable PLA mask was found to have good filtration performance, respiratory resistance, thermal comfort management performance, fittness, and degradability, and the PLA mask prepared by this method also provides a new idea for the development of biodegradable masks.

Key words: biodegradable, mask, polylactic acid, melt-blown spinning, electrostatic spinning, filtration efficiency