Universal masking during COVID-19 pandemic: Can textile engineering help public health? Narrative review of the evidence.

The Coronavirus Disease-2019 (COVID-19) pandemic caused by the virus SARS-CoV-2 is spreading very quickly around the world. In less than 7 months since it became known to the international community, the virus has infected 18 million in more than 180 countries and killing more than 700,000 people. Person-to-person transmission through infected respiratory droplets from patients with symptoms and asymptomatic carriers is the main mode of spread in the community. There is currently no standard agreed upon drug to treat the disease and the prospect of having a safe and efficacious vaccine might be years away. Thus, public health interventions such as social distancing and hand washing have been introduced and has, to some extent, slowed the progression of the pandemic. Universal masking as a public health intervention is currently mandatory in a vast majority of countries around the world. To avoid personal protective equipment (PPE) shortage crisis for medical staff and other frontline workers, health authorities are recommending the use cloth masks. Although in theory, cloth masks can be helpful to limit the spread of the COVID-19, serious consideration should be given to the choice of textile, the number of layers of cloth used, pre-treatment of the material with water repellent material and other compounds that can enhance the filtration efficiency of the masks without compromising their breathability. This review uses concepts of textile engineering and the theoretical principles of filtration to make suggestions and recommendations to improve the quality and safety of cloth masks for the general public.

Development of superhydrophilic and superhydrophobic polyester fabric by growing zinc oxide nanorods.

ZnO nanorods were grown on microfibers of Polyethylene terephthalate (PET) fabric by seeding method to develop hierarchical roughness structure. XRD and XPS analysis show the presence of crystalline ZnO and chemical Zn species at the fiber surface at each stage of the process. Five series of samples with different seed concentrations have been realized, and their surface morphology and topography were characterized by AFM and SEM. Increasing seed concentrations lead to samples with superhydrophilic properties. Not only the water contact angle at fabric surface tends to zero but also the water capillary diffusion inside fabric is faster. Nanostructuration affects the structure inside the fabric, and further experiments with decane liquid have been made to get a better understanding of this effect. To study the superhydrophobicity, nanorods treated samples were modified with octadecyltrimethoxysilane (ODS) by two method; solution deposition and vapor deposition. The superhydrophobicity was characterized by measuring the water contact angle and water sliding angle with 5 µl water droplet. The samples modified with ODS by vapor deposition showed higher water contact angles and low water sliding angle than the ones modified with solution method. The lotus effect has been well correlated with the surface morphology of the nanorods structured fibers. The application of the Cassie-Baxter equation is discussed.

Polypropylene film chemical and physical modifications by dielectric barrier discharge plasma treatment at atmospheric pressure.

Dielectric barrier discharge (DBD) technologies have been used to treat a polypropylene film. Various parameters such as treatment speed or electrical power were changed in order to determine the treatment power impact at the polypropylene surface. Indeed, all the treatments were performed using ambient air as gas to oxidize the polypropylene surface. This oxidation level and the surface modifications during the ageing were studied by a wetting method and by X-ray photoelectron spectroscopy (XPS). Moreover polypropylene film surface topography was analyzed by atomic force microscopy (AFM) in order to observe the surface roughness modifications. These topographic modifications were correlated to the surface oxidation by measuring with a lateral force microscope (LFM) the surface heterogeneity. The low ageing effects and the surface reorganization are discussed.