Preparation and Characterization of PTFE/PI Nanofiber Composite Assembled Sponges

Abstract

Due to the ultralow density and high specific area, nanofibrous sponges show great potential in the field of filtration and separation. To prepare nanofibrous sponges for high temperature smoke filtration, polytetrafluoroethylene (PTFE) was chosen due to its corrosion resistance and high temperature resistance. PTFE nanofiber prepared via electrospinning shows irregular concave-convex pores in the fiber body, which can improve the specific surface area and further enhance filtration performance. However, sponges made of PTFE nanofiber suffered from severe shrinkage, which limited the development in sponge products. In this study, polyimide (PI) nanofiber converted from polyamic acids (PAAs) nanofiber was introduced into the PTFE sponges to reinforce the dimensional stability. The parameters that influenced the morphology, porosity, shrinkage ratio, and thermodynamic properties of the composite sponges were also investigated. Moreover, the filtration performance of the composite sponges was tested. Results indicated that PTFE/PI composite nanofiber sponges possessed high porosity (94.34–98.12 %), excellent thermal stability (above 550 °C), and decent filtration efficiency (the maximum filtration efficiency reached 99.97 % to PM 2.0) were prepared, which demonstrated the potential in the field of high-temperature filtration.