Page 604 - Polymer-based Nanocomposites for Energy and Environmental Applications

Nanofibrous composite air filters 557

20.3 Production methods of nanofibrous composite
air filters

20.3.1 Nanofibrous composite air filter production by
electrospinning

The typical lab-scale electrospinning setup consists of a syringe filled with a polymer
solution, a collector plate, and a power supply to provide the required electric force.
When the electric forces at the surface of a polymer solution overcome viscosity and
surface tension, an electrically charged jet is ejected through the nozzle. Assuming a
typical one-nozzle system (production rate 0.1–1 mL/min), the required potential is
about 20 kV at a current of 3 mA. Novel approaches that are concentrated on the basic
air filtration requirements will be summarized here.
Xu et al. [12] developed a new electrospinning mechanism (Fig. 20.3) to obtain
uniform fiber deposition on supported meshes. First of all, a plastic mesh was coated
with polymer solution. Secondly, nanofibers were coated on a rough copper foil.
Thirdly, plastic mesh and nanofibers were laminated to the copper foil under compres-
sion, resembling a sandwich structure. Finally, plastic mesh and nanofibers were
transferred from copper foil. According to the investigations with an optical micro-
scope, the transferred nanofiber membrane has more uniform distribution compared
with direct electrospun mesh [12].

Fig. 20.3 (A) and (B) Schematic illustration for the fabrication of transparent air filter by direct
spinning on a conductive mesh and OM image of corresponding filter. Scale bar in B is 200 μm.
(C) and (D) Schematic illustration of the fabrication of transparent air filter by transferring
electrospun nanofiber film onto a plastic mesh and OM image of corresponding filter. Scale bar
in B is 200 μm. (E) and (F) Schematic illustration of the transfer of freestanding electrospun
nanofiber film and photograph of corresponding film. Scale bars are for 5 cm [12].