BEHAVIOUR ASSESSMENT OF TRIDIMENSIONAL MULTILAYER FIBROUS STRUCTURES AS RESPIRATORY PROTECTION SUBSTRATES

Abstract

Despite the growing appearance of new solutions for social masks, there are still few aimed for the use by professionals in frequent contact with the public, since depending on the of the functions they perform, still have special needs regarding thermophysiological comfort, high protection level and reusability, such as firefighters and police officers. Aiming at the development of a multilayer filtration system combining threedimensional and planar fibrous structures, the present study intends to verify the feasibility of applying warpknit spacers as diffuser filters for nano and micro particles. Therefore, three different spacer structures performance was studied, and then combined with planar knit structures to enhance the comfort characteristics and its bacterial filtration efficiency (BFE). The diffusion filtration performance of the samples, due to the particle size, it was found a direct relation between the outer layer density and porosity with its filtration capacity of microparticles. Moreover, the increase in the spacer thickness revealed more problems diffusing water vapor molecules. To achieve the standard requirements, the samples Techno_1 and 2 were developed and tested. The addition of a new fibrous structure increased substantially the filtration efficiency without damaging the comfort characteristics of the Spacers. Considering the BFE standard tests for facemask certification, despite it was possible to achieve filtration rates above 70% for the samples Techno_1 and 2. In addition, its washability and performance durability were tested and stated as viable to be applied as a social facemask with level III of protection for at least 25 washing cycles, despite having noticed a decrease in the filtration efficiency, in both samples, in the order of 10%, due to the unbalance of mechanical properties of the fibrous structures in the multilayer systems.