PTFE Emulsion Foam Coating Finishing of Needled Pre-oxidized PAN/PPS Composite Filters

In order to improve the filtration properties of needled pre-oxidized PAN/PPS composite filters, a series of composite filters were prepared through foam coating. The morphology, porosity, air permeability, pore size and filtration properties of filers were evaluated. The results showed that with increasing of PTFE emulsion containing in coating solution, the porosity, air permeability, pore size and pressure drop of filters decreased. When the ratio of PTFE emulsion above 10 %, the pressure drop increased more significantly with the increase of ratio of PTFE emulsion, compared with the ratio of PTFE emulsion below 10 %. The filtration efficiency of filters increased with the increase of ratio of PTFE emulsion. For particles with a diameter of >= 2.5 mu m, the filtration of filters finished by foam coating was as high as 99.72 %.