الفهرس 
GENERAL INTRODUCTION AND LITERATURE SURVEYOnly 14 pages are availabe for public view
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Abstract
The purpose of the work in this thesis is mainly directed to preparation and characterization of Polyaniline / Polyvinylalcohol (PANI)/PVA) nanocomposite at different irradiation times, (3, 6 ,9, 12 and 15 ) min., at room temperature by using (CW-Diode -807 nm at power 1500 mW). The vibrational structures are studied using FTIR spectrometer. The UV-Visible region is also investigated. The effect of irradiation time on the particle size and the crystallinity are studied using Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The DC electrical conductivities are studied (303 to 423) K ,and activation energies are calculated . The real part of dielectric constant (έ) and imaginary part (ε”) , and relaxation time are also studied .
The thesis includes five chapters:-
The first chapter : a general introduction is given which includes a general review of the important work concerning the determination of the molecular structure and electronic distribution, and electrical conductivity. The end of the first chapter presents the aim of the present work.
The second chapter of this thesis exhibits a complete review on the theoretical concepts of molecular structure, electronic spectra, Transmission Electron microscope (TEM), X-ray diffraction (XRD), and electrical properties.
The third chapter describes the preparation methodology, experimental setup and techniques . Fourier Transform Infrared (FTIR) Spectrometer, UV-Visible spectrophotometer, Transmission Electron microscope (TEM), X-ray diffraction (XRD), and study the electrical properties.
The fourth chapter includes the results and discussion in five main parts:-
1-Infrared spectra:
• By comparing PANI/PVA composite and PANI /PVA nanocomposite at different irradiation times (3, 6, 9, 12and 15 ) min., it is observed that the two absorption bands of N=Q=N and B-N-B, for the quinonoid and the benzenoid structures at 1651cm-1 and 1436 cm-1 shifted to higher wavenumber (1659, 1664,1668,1668,1669) cm-1 and (1439, 1442, 1442,1442,1443) cm-1 with increasing irradiation time to (3,6,9,12 and 15) min., respectively.
• The stretching vibration of hydrogen bond (O-H) of the absorbed water of PANI/PVA composite which appeared at wavenumber (3350 cm-1) are shifted to higher wavenumber (3365 ,3361 ,3354 ,3354 ,3357 ) cm-1 at irradiation times (3,6,9,12, and 15) min., respectively .
• New bands have appeared in the FTIR spectrum of PANI /PVA composite at (2360 , 2361 and 2363) cm-1 at irradiation times (9, 12 and 15) min., respectively, due to the stretching vibration of CH2 group for carboxylic acid in the PANI .
• The relative intensities of the absorption peaks at 1651 cm-1 to that at 1436 cm-1 (I1651/I1436) of PANI/PVA nanocomposite have increased with increasing irradiation times from (0.8184 to 1.1078). This indicates that the benzeniod unit has changed into quinoid structure in PANI/PVA nanocomposite and PANI in the emeraldine salt form.
2-Electronic spectra
• We have observed that, with increasing irradiation time for investigated samples, the π- π* absorption band at 230 nm and n-π* absorption band at 286 nm have slightly shifted towards higher wavelength (bathscromic shift) at (232 ,238 ,236 ,236 and 236 ) nm and (292 , 296 .296 , 294 and 296) nm respectively.
• The new bands which appeared at (556 ,564 ,564 ,562 and 564 ) nm for irradiation time at (3,6,9,12 and 15) min., respectively ,are corresponded to π- polaron transition, which are characteristic of the protonated PANI. This band is ascribed to cation radicals, and indicates the formation of polaron and PANI in emeraldine salt form .
• New band has appeared at (668 ,670 and 680 ) nm in the UV-Vis spectra of PANI/PVA nanocomposite which is assigned to n-π* transition .
3-from the Transmission Electron Microscopy (TEM) results:
• The TEM images show that the PANI/PVA nanocomposite have an external spherical morphologies shape with size ranges from 6 to 14 nm at the irradiation times (3,6,9,12 and 15) min., respectively.
4-X-Ray Diffraction Pattern Results:
• XRD data show that the degree of amorphous in PANI/PVA nanocomposite at irradiation times (6, 9, 12, and 15) min., is less than PANI/PVA composite. This is in consistent with the conformational changes of the PANI/PVA nanocomposite together with the increased sharpness in the amorphous scattering at 2θ of (19.59o,19.46o,19.49o,19.44o,19.27o) at irradiation times (3,6,9,12 and 15) min., the particle size decreases with increasing irradiation time (9.9 to 4.94) nm.
5- Electrical Conductivity:
• The DC electrical conductivity has been calculated at room temperature. The behavior of the electrical conductivity of the investigated samples shows that they are conductor.
• DC conductivity of PANI/PVA composite is1.85×10-8 Ω-1.cm-1 and increases with increasing irradiation times to (7.9×10-7, 4.6×10-6, 4.3.×10-5, 3.1×10-4 and 4.7×10-4) Ω-1.cm-1 at ( 3,6,9,12 and 15) min., respectively. This increase can be assigned to the increase in the mobility of charge carriers and the increase in the rate of charge carrier generation.
• The increase in conductivity indicates that there is a transition from PVA/AniHCl dielectric polymer blend to PVA/PANI conducting nanocomposites following irradiation.
• The activation energies of PANI/PVA nanocomposite decrease, with increasing irradiation time from (3,6,9,12 and 15) min., at (0.18, 0.17, 0.15, 0.14 and 0.13) eV, respectively, and the conduction mechanism follows the tunneling model.
• By comparing the variation of the real part of dielectric constant of PANI/PVA composite with PANI/PVA nanocomposite films at different irradiation times, at (3,6,9,12 and 15 ) min., as a function of frequency ranging from 500 kHz to 5 MHz and measured at different temperatures (303,333,363 and 393 K) it is clear that the dielectric constant increases with increasing of temperature. This increase may be attributed to the orientation of the dipoles which formed from the charge carriers.
• By comparing the variation of dielectric loss ε” for PANI/PVA composite and PANI/PVA nanocomposite with increasing the irradiation times, at (3,6,9,12 and 15 ) min., as a function of frequency at different temperatures, we have two types of losses. One is a conduction loss, representing the flow of actual charge through the dielectric. The other is a dielectric loss due to movement or rotation of the atoms or molecules in an alternating electric field.
• It is observed that the relaxation time of PANI/PVA composite is higher than that of PANI/PVA nanocomposite due to stronger bonds in pure polyaniline chain than nanocomposite.
Finally, fifth chapter: includes the general conclusion and provides details of the concluded experimental results .