الفهرس 
Preparation, characterization and study of some physical properties of nanocomposites based on polyvinyl alcohol and barium titanate
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Abstract
High-k materials (high permittivity ε’) are of extraordinary demand for the
miniaturization of electronic devices. In particular high- k polymer / inorganic
composites which can be tailored to the electromagnetic applications. Polyvinyl
alcohol (PVA) as a host green biodegradable polymeric matrix was chosen to
fabricate novel polymer nanocomposites with different concentrations of magnetite
(Fe3O4) nanoparticles and different concentrations of barium titanate (BaTiO3)
nanoparticles before and after treatment or modification with ionic liquid (IL) as a
dopant using casting method. The particle size of magnetite (Fe3O4) nanoparticles
and barium titanate (BaTiO3) nanoparticles were determined using the transmission
electron microscope (TEM). The morphology and structural properties of those
nanocomposites were inspected by scanning electron microscopy (SEM) and X-ray
diffraction (XRD) respectively. SEM indicates good dispersion of Fe3O4
nanoparticles and ionic liquid treated BaTiO3 inside PVA matrix. Whereas, XRD
data revealed a notable increase in the degree of crystallinity by increasing IL
treated BaTiO3 loading. Fourier Transformation Infrared Spectroscopy (FTIR) of
PVA through its respective functional groups was noticed by addition of Fe3O4
nanoparticles and BaTiO3 nanoparticles before and after modification as well. A
considerable change in characteristic peaks in the FTIR spectra was detected. The
mechanical parameters; tensile strength (σR), elongation (εR) and hardness (Hv)were also investigated. Mechanical properties investigations revealed that 10
(Fe3O4 / IL treated BaTiO3) wt% is the optimum concentration. Moreover, microhardness increases with the increase of the Fe3O4 content, as well as after
modification of BaTiO3 with the ionic liquid. The magnetic properties were
investigated by vibrating sample magnetometer (VSM) and the obtained data
disclosed an enhancement in magnetic properties by the ionic liquid treatment and
clearly demonstrate ferromagnetic behavior. This finding widens the application
scope of PVA nanocomposites to include electromagnetic purposes. The dielectric
properties of the PVA nanocomposites were investigated over wide frequency
range (0.1Hz-1MHz). The presence of BaTiO3 and /or Fe3O4 significantly increased
permittivity ’ and dielectric loss ” and enhance the ionic conductivity of the
PVA. The role of treatment of BaTiO3 by ionic liquid on the later mentioned
parameters was interpreted. The values of conductivity were found to be in range of
10-5
–10-9 S/cm, suggests the use of such composites for electrostatic dissipation
applications.