The tendency to enhance the dielectric properties
of insulating materials used in cables has become necessary in
order to design new insulation systems that can withstand higher
voltage levels. The current study is to investigate the
improvement in dielectric properties of Polyvinyl Chloride (PVC)
due to the insertion of chemically functionalized titanium oxide
(TiO2) nanoparticles. The functionalization of TiO2 nanoparticles
was performed using vinyl silane coupling agent. The PVC/TiO2
nanocomposites, with different weight fractions of nanoparticles
up to 5 %, were fabricated using solution casting of PVC with the
aid of nanoparticles dispersion within the molten polymeric
matrix. The surface morphology of synthesized PVC/TiO2
nanocomposites was characterized by field emission scanning
electron microscopy (FE-SEM). Then, their dielectric properties
were studied by measuring and simulating the AC dielectric
breakdown strength under quazi-uniform electric fields. The
relative permittivity (εr) and dielectric loss (tan δ) were also
measured in the frequency range 20 Hz to 1 MHz at room
temperature. It is found that the dielectric breakdown strength of
PVC was increased with incorporating functionalized TiO2 into
their matrix compared to that with un-functionalized TiO2 or
that of unfilled PVC. Furthermore, εr and tan δ were decreased
by about 43% and 41%, respectively, over the unfilled PVC at 50
Hz. 3 % was found the optimal loading fraction of functionalized
TiO2. This reveals that PVC/TiO2 nanocomposites with
functionalized TiO2 had better dielectric properties. This may be
attributed to the low surface energy of the functionalized TiO2
nanoparticles that prevented the agglomeration of nanoparticles
and restricted the mobility of polymeric chains, and in turn,
suppressed the free space charges resulting in a decrease in the
capacitance and losses inside the nanocomposites. |
