Abstract:
Polymer nanofibers have attracted a lot of industrial interest in the past decade. In general, these
fibers need to be thermally stable for many applications, such as in the aerospace industry.
However, most of these polymer nanofibers suffer from low temperature degradation, limiting
their use in many potential applications. Graphene, which is one sheet of graphite, has unique
properties such as high conductivity, and high thermal stability. This exceptional material can be
incorporated into the polymer nanofibers as nanofillers in order to enhance their thermal
properties.
The aim of this dissertation is to investigate the effect of adding graphene nanofillers into the
polymer fiber on the resulting fibers’ thermal properties. For that purpose, polyvinyl alcohol
(PVA), a non-conductive polymer and a different source of graphene, namely graphene foam,
expendable graphite and graphite powder were used. The growth technique was the
electrospinning technique which offers a variety of parameters that need to be optimized. For this
includes, the amount of PVA in the water solvent, the flow rate, the applied voltage, the growth
time, and the tip/collector distance. In summary, it has been optimized that the best conditions
for growth of fibers will be as follows: PVA concentration will be fixed at 10 wt%, flow rate will
be 3 ml/h, applied voltage will be 30 kV, growth time of 60 s and tip/collector distance will be
fixed at 12 cm. The resulted PVA fibers from these conditions were smooth continuous and
hollow with diameter ranging between 190-340 nm, while PVA/graphene nano-fibers are much
thinner with diameter ranging between 132 - 235 nm when the same parameters were used with
only graphene concentration varied.
The fiber obtained with PVA showed a hollow structure which is desirable for incorporation of
graphene nanofillers. The dispersion of the different source of graphene sheets in the starting
PVA solution showed enhanced thermal stability compared to the PVA fibers alone.
Furthermore, an increase in the thermal stability is observed with increasing concentration of
graphene nanofillers. This work shows the promising use of graphene as nanofillers for PVA fibers. This can be
expended to other non-conductive and conductive polymers in order to broaden the application
of these fibers in the industries, where thermal stability is a prerequisite.
