Piezoelectric Energy Harvesting Nanofibers - Hierarchical Nanostructures for Energy Devices - page 148

far-field electrospinning process have either measurements on the strong
contents of b-phase PVDF, 21,22,32-34,59-62 or electrical signals of piezoelectric
effects in applications such as sensors 37 or energy harvesters. 21,22

d n 3 r 4 n g | 2

7.2.4 Mechanical Forcespinning
Another process, mechanical forcespinning, can also construct fibers. 58,59 In
a recent study, the roles of mechanical stretching and electric poling for the
conversion from a-tob-phase PVDF has been investigated for fibers
fabricated by the electrospinning and mechanical forcespinning process
using FTIR and XRD spectroscopic techniques. Figure 7.2(a) and (c)
show the fabricated fibers from the 'baseline' polymer solution (16 wt%
and V NMP /V acetone ¼ 5/5) by electrospinning and forcespinning processes,
respectively, while Figure 7.2(b) illustrates the force spinning process. 60 The
electrospun fibers are constructed under an electrical bias of 7.5 kV with a
polymer solution flow of 60 mL per hour and electrode-to-collector distance

.

Figure 7.2 (a) SEM photos of PVDF fibers from prototype (7.5 kV, 60 mL per hour

0 cm) electrospinning; (b) schematic diagram of the forcespinning setup;
(c) SEM photos of PVDF fibers from high-speed (11 000 rpm) forcespin-
ning; (d) XRD patterns and (e) infrared spectra of the above electrospun
fiber mat and forcespun PVDF fiber mat. The same polymer solution
(16 wt%, V NMP /V acetone ¼ 5/5) is used for both spinning experiments.
Reproduced from ref. 60 with permission from the Royal Society of
Chemistry.