Page 610 - Polymer-based Nanocomposites for Energy and Environmental Applications

Nanofibrous composite air filters 563

Fig. 20.10 (A) Schematic illustration of the production of N6-PAN NNB hybrid membranes on
nonwoven substrate, (B) showing of N6-PAN NNB onto substrate, (C) FE-SEM image of
membrane, and (D) filtration process of membrane [16].

had a concentration of 9 wt% in dimethylformamide. They applied two different
experimental mechanisms, which were different concentrations of N6 and varied
jet ratios of N6(15)-PAN (4:0, 3:1, 2:2, 1:3, and 0:4) as seen in Fig. 20.10 [16].
The research focused on several characteristics for filter medium, such as small
fiber diameter, little pore size, uniform membrane structure, high porosity, low pack-
ing density, and leashed turbulent airflow channel [16]. N6 nanofibers generally
included 1-D nanofibers and 2-D nanowebs. The average diameters of N6-10,
N6-12.5, N6-15, and N6-17.5 were 121, 138, 272, and 303 nm, respectively. It could
be seen that the fiber diameter increases with increasing concentration. The N6-15 had
highest filtration performance properties, which were 95.20% of filtration efficiency
2
(basis weight of 0.42 g/m ), 86.2 Pa of pressure drop, and 0.036 Pa 1 of QF. The
specific surface area (SSA) of N6 nanofibers decreased with an increase of concentra-
2
tion, which was from 29.918 to 16.936 m /g. The dispersion of nanofibers improved by
increasing jet ratio of N6-PAN between 3:1 and 0:4. The increasing content of PAN
from 0.2723 to 0.1306 causes decline in packing density of N6-PAN membrane. It was
found that the pore sizes of N6-PAN4/0, N6-PAN3/1, N6-PAN2/2, N6-PAN1/3, and
N6-PAN0/4 hybrid nanofibers were 188, 231, 276, 370, and 756 nm, respectively. In
addition, the porosities of N6-PAN4/0, N6-PAN3/1, N6-PAN2/2, N6-PAN1/3, and
N6-PAN0/4 were determined as 66.89%, 73.10%, 86.92%, 89.93%, and 91.87%,
respectively. As a result, N6-PAN2/2 exhibited better filtration performance
1
(99.99%) and higher QF (0.1163 Pa ) [16].

20.3.2 Nanofibrous composite air filters via nonelectro fiber
spinning techniques
There are also other methods to process polymeric materials into nanofibers. Those
include solution/melt blowing, drawing techniques, template synthesis, centrifugal
spinning, freeze/drying synthesis, interfacial polymerization, self-assembly, and