The masks have always been mentioned as an effective tool against environmental threats. They are considered as protective equipment to preserve the respiratory system against the non-desirable air droplets and aerosols such as the viral or pollution particles. The aerosols can be pollution existence in the air, or the infectious airborne viruses initiated from the sneezing, coughing of the infected people. The filtration efficiency of the different masks against these aerosols are not the same, as the particles have different sizes, shapes, and properties. Therefore, the challenge is to fabricate the filtration masks with higher efficiency to decrease the penetration percentage at the nastiest conditions. To achieve this concept, knowledge about the mechanisms of the penetration of the aerosols through the masks at different effective environmental conditions is necessary. In this paper, the literature about the different kinds of face masks and respiratory masks, common cases of their application, and the advantages and disadvantages of them in this regard have been reviewed. Moreover, the related mechanisms of the penetration of the aerosols through the masks are discussed. The environmental conditions affecting the penetration as well as the quality of the fabrication are studied. Finally, special attention was given to the numerical simulation related to the different existing mechanisms.

It is clear that viruses, especially COVID-19, can cause infection and injure the human body. These viruses can transfer in different ways, such as in air transfer, which face masks can prevent and reduce. Face masks can protect humans through their filtration function. They include different types and mechanisms of filtration whose performance depends on the texture of the fabric, the latter of which is strongly related to the manufacturing method. Thus, scientists should enrich the information on mask production and quality control by applying a wide variety of tests, such as leakage, dynamic respiratory resistance (DBR), etc. In addition, the primary manufacturing methods (meltblown, spunlaid, drylaid, wetlaid and airlaid) and new additive manufacturing (AM) methods (such as FDM) should be considered. These methods are covered in this study.

The thermocompression molding process allows composites to be made with longer fibers compared to injection molding and extrusion. However, during thermo-compression molding fiber-reinforced composites are exposed to complex effects, which can lead to specific fiber orientation/distribution and therefore affect the mechanical properties. The aim of this work is to study the effect of fiber orientation on the mechanical properties of the long-glass-fiber-reinforced polypropylene (GF50-PP) composite produced by the thermocompression process. Moreover, due to the application of this composite in cold liquid gas storage, it is interesting to study this effect under cryogenic conditions. In this study, composite plates of GF50-PP were cut to analyze the effect of fiber orientations: 0°, 45°, and 90° with respect to the Mold Flow Direction (MFD). After microstructural observations by SEM microscopy and physico-chemical analysis, the mechanical behavior of GF50-PP samples was examined at monotonic tensile loading and tension-tension fatigue at two loading temperatures of 20°C and -70 °C. The results of the tensile tests revealed that the values of stress at break were almost similar at 20°C and -70°C for different fiber orientations of 0°, 45° and 90° and that the temperature effect for the two test conditions is almost insignificant. The tensile-tension fatigue tests at 20°C show the significant effect of the orientation of the fibers when the amplitude of deformation is important. On the other hand, when the amplitude is small, this effect is negligible. In this case, all samples exhibit almost the same behavior. However, during fatigue tests at -70 ° C (cryogenic temperature), the material shows almost uniform linear behavior, but still sensitive to the orientation of the fibers.