الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
Preparation and characterization of green synthesized gold nanoparticles : The present thesis focuses on preparation the gold nano patricles (Au NPs) by green synthesis method. Eco-friendly synthesized gold nanoparticles (Au NPs) were successfully prepared via facile biosynthesis of plants leave extracts. Biosynthesized Au NPs were characterized by Ultraviolet/Visible spectroscopy (UV-vis.), Transmission electron microscopy (TEM), X-ray diffraction (XRD). UV/Vis. measurements of Au NPs prepared using Chenopodium murale shown broad absorption band in the visible region at 548 nm is assigned to the surface plasmon resonance (SPR) peak of Au NPs. The typical TEM images of the obtained Au NPs have many shapes such as hexagonal, sphere and irregular shapes. XRD analysis was used to investigate the crystalline structure of the synthesized Au NPs. The prepared gold nano particles have been added to polymer blend in two systems. Second System : Preparation and characterization of polyvinyl pyrrolidone/sodium alginate blend containing different concentration of Au nanoparticles : Casting technique was employed for preparation of polyvinyl pyrrolidone/sodium alginate films (50/50 wt. %) with and without different concentrations of gold nanoparticles (AuNPs) as nanofiller which was biosynthesized by Chenopodium murale leaf extract. In order to investigate the physical properties of the prepared samples, different techniques had been used such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy for structural properties, Ultraviolet and visible (UV/Vis.) spectroscopy for optical properties, Scanning electron microscopy (SEM) for surface morphology, AC electrical resistivity for electrical properties. XRD proved the amorphous nature of the pristine and filled polymer blend which showed well-defined broad peaks at about 13° and 23°. X ray diffraction results indicated that the amorphousity of PVP/SA was increased after embedding of gold nanoparticles due to the coordination interactions between the gold nanoparticles FT-IR spectra depicted the main characteristic peaks of these materials and implied that complexation occurred in the amorphous region which confirms XRD results. UV/Vis. spectroscopy was used to retrace the optical changes with increasing Au content. Also, the UV/Vis. spectra exhibited a shift for the sharp absorption edge towards longer wavelength with increase the nanofiller content in the polymeric matrix. The red shift of the absorption edge in the filled PVP/SA indicates the complexation between the nanofiller and the polymer blend as in XRD and FT-IR analysis. SEM were studied the morphological properties for the prepared samples. Scanning electron microscopy revealed the partial compatibility between the polymer blend (PVP/SA) and the Au NPs. Scanning electron microscopy exhibited some granules appeared on the surfaces of the filled samples as bright spots. These bright spots seem to be agglomerates of AuNPs. AC conductivity showed an enhancement for the conductivity, dielectric permittivity (ɛ’) and dielectric loss (ɛ””) of (PVP/SA. The value of the activation energy (Ea) of the dielectric relaxation is calculated and is found to be 0.18 eV TEM images confirmed the creation of gold nanoparticles in the nano size range 10–15 nm. In addition, the results of transmission electron microscopy behave in good agreement with previously recorded UV/Vis. analysis. Third system : Preparation and characterization of polyethylene oxide/sodium alginate blend containing different concentration of Au nanoparticles : Casting technique was employed for preparation of polyethylene oxide/sodium alginate films (50/50 wt. %) with and without different concentrations of gold nanoparticles (AuNPs) as nanofiller which was biosynthesized by Chenopodium murale leaf extract in the first system. The following techniques have been used to investigate the physical properties for blend/Au nanocomposite : XRD, FT-IR, UV/Vis, TEM, AC electrical conductivity. XRD proved the semi-crystalline nature of the pristine and filled polymer blend which showed well-defined broad peaks at about 19° and 23°. The intensities of the two intrinsic peaks are randomly decreased and the content of amorphous phases was improved. This reduction indicates that the degree of crystallinity of polyethylene oxide and sodium alginate is disturbed due to the coordination interactions between the gold nanoparticles. The FTIR spectra showed some limited changes in the IR absorption bands. This reveals an interaction between Au NPs and polymer blend. UV-Vis analysis shown that the values of the optical energy gap are decrease with increasing filler concentration this indicates that there is a charge transfer complexes arises between the polymer blend and Au NPs, which confirm that the addition of Au NPs can improve the electrical properties of the polymer blend. The AC conductivity was found to increase with the increase of the frequency. The correlated barrier hopping (CBH) model was found to be applying to the ac conductivity data. Fourth system : Effect of Gamma-irradiation on (PEO/SA)/ Au nanocomposite : Materials for electrochemical and optical applications The following techniques have been used to investigate the physical properties for blend/Au nanocomposite before and after Gamma-irradiation at different doses (2, 4 and 6 MR): XRD, FT-IR, UV/Vis, TEM, and AC electrical resistivity. XRD confirmed the semicrystalline nature of PEO/SA polymer blend which was largely decreased after embedding Au NPs and subsequently through high-irradiation doses of γ-rays. The FT-IR study confirmed that due to the addition of Au NPs and irradiation process, the main polar groups of blend, C-O-C of PEO and COO-of SA, were significantly influenced. UV/Vis. spectra showed that the shift in absorption edge and optical parameters (optical energy gap Eg) for irradiated nanocomposite films depends largely on the irradiation dose and the increase in intensity of SPR peak is related to the increase of the fraction of Au NPs at high irradiation doses (6 MR) and its location is moved to longer wavelength indicating formation of smaller particles due to its quantum size effect. TEM micrographs showed that the particle size distribution for PEO/SA/Au nanocomposite is enhanced due to high-irradiation doses. In addition, the results of TEM behave in good agreement with previously recorded UV/Vis. analysis. AC measurement : As a result of the irradiation process, an increase in the conductivity of PEO / SA-Au NPs is observed as well as in the dielectric permittivity (ɛ′) and dielectric losses (ε″) of PEO / SA-Au NPs. The relationship between M′′ and M′ reflects the creation of a semi-circular arc that demonstrates the presence of a wide variety of relaxation processes.