Composite electrospun membranes based on polyacrylonitrile and cellulose nanofibrils: Relevant properties for their use as active filter layers

Electrospun membranes comprising polyacrylonitrile (PAN) and 0.2 to 0.6 wt% cellulose nanofibrils (CNF) were prepared and characterized for their use as active layers of Filtering Facepiece Respirators (FFRs) and medical masks. Composite membranes with up to 0.4 wt% of CNF exhibited storage modulus values up to approximately 5 times higher and tensile strength and elastic modulus about 2 times and 6 times higher, respectively, compared to neat PAN. All membranes presented filtration efficiencies (FE) superior to 90% for aerosols with a median count diameter of 75 +/- 20 nm and geometric standard deviation less than 1.86. For most membranes produced from an equal volume of solution, the increase in CNF content decreased the pressure drop (Delta p, up to approx-imately five times) and increased the quality factor (QF, up to about 4 times) of the composite membranes, compared to neat PAN, due to the formation of more heterogeneous fibers, larger pores, a trend of increasing porosity and lower packing density. The presence of CNF also increased the air permeability (permeability co-efficients, k1 and k2) of the composite materials. Following a yet not explored approach, it was demonstrated that the presence of CNF in the composition of PAN composite electrospun membranes led to materials with better performance as active filter layers than neat PAN.

Automated summary

Electrospun membranes comprising PAN and 0.2 to 0.6 wt% CNF were prepared and characterized for use in FFRs and medical masks. The addition of CNF led to membranes with significantly improved mechanical properties and filtration efficiency. The presence of CNF also affected the pressure drop, quality factor, and air permeability of the composite materials.