الفهرس 
General Background and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
Rapid population expansion, industrial activity, and automobiles are the principal sources of emissions discharged into the atmosphere, which typically exacerbate natural environmental conditions on a local to global scale. Nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), hydrogen sulphide (H2S), and methane (CH4) are the most dangerous of these pollutants. Toxic gases and fumes originate in the combustion of specific fuels or in direct manufacturing. Carbon monoxide and hydrogen cyanide, the two most frequent hazardous gases responsible for inhalation injury, play important roles in smoke inhalation injury. Carbon dioxide, nitrogen, aliphatic hydrocarbon gases (butane, ethane, methane, and propane), and noble gases (argon, helium, neon, radon, and xenon) are among examples of simple asphyxiants kill by preventing oxygen from entering the lungs. Numerous devices are available for detecting pollutants and hazardous gases. The current study intends to develop a novel polymer nanocomposite that can detect harmful gases.
In this concern, the present thesis consists of five main chapters as the following:
Chapter 1: Describe a basic overview of the subject as well as a quick review of previously published scientific publications in the field of interest.
Chapter 2: Introduces the theoretical background of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible-near-IR (UV-Vis-
NIR) spectroscopy measurements.
Chapter 3: The first part of this chapter explained how to synthies nano particles GO and nanocomposite GO/ZnO using the precipitation method and how to prepare polymer nanocomposite samples PVDF/GO/ZnO using the casting method. After that, the laser assisted method to exposed the prepered films to laser beam at different times. The second section was devoted with describing and a brief description the analytical methodologies employed during the thesis preparation, which are XRD, FTIR and UV-Vis-NIR spectrophotometer. Additional theoretical computation details were introduced.
Chapter 4: This chapter presents the results of experimental and theoretical work for the characteristic curves of the prepared nano particles GO, nano composite GO/ZnO and PVDF polymer nanocomposites under study, from which it was possible to derive their different optical coefficients. The research was expanded to include the use of polymeric nanocomposite films as gas sensor.
Chapter 5: Conclusion and future work.
In this thesis, polymer nanocomposite films were prepared based on nanocomposite GO/ZnO and polyvinylidene fluoride (PVDF), finally polymer nanocomposite films prepared and studying the possibility of applying them in sensor application as gas sensor.
Accordingly, the precipitation method was utilized to synthesis nanocomposite GO/ZnO. Meanwhile, the solution casting method was utilized to synthesis hybrid polymer nanocomposite films. With laser assisted method, the films exposed to laser beam at different times.
For polymer nanocomposite films the following results was observed:
The parameters of micro-structural of the synthesized nanoparticles GO is affected by the incorporation of ZnO-NPs. XRD results supported the creation of the nanocomposite due to the appearance of a number of diffraction peaks belongs to GO and ZnO-NPs. Additionally, the results showed that the crystallite size of the PVDF nanocomposite samples decreased with increasing nanocomposite concentration become amorphous crystal. FTIR results revealed that the protons of the PVDF were turned into free ions forming a hydrogen bond with nanocomposite.
UV-Vis-NIR optical spectroscopy investigates the effect of nanocomposite GO/ZnO concentration on PVDF’s optical properties. With increasing nanocomposite concentration, the gap energy decreased, corresponding to the crystallite size reduction. The absorption analysis has been performed to determine the type of transitions and the optical energy gaps of PVDF and PVDF nanocomposite films. The type of transition was found to be a direct allowed transition. The value of the optical band gap energy of PVDF was decreased due to nanocomposite GO/ZnO addition and decreased with increasing nanocomposite GO/ZnO concentration. And also, the transmittance of all samples is decreased with increasing the GO/ZnO nanocomposite.
Urbach energy is determined and increase with increasing concentration of GO-ZnO nanocomposite. This is indicates to the creation of localized states at the band gap as a result of the addition of GO-ZnO nanocomposite, as increase the disorder of material.
Finally, molecular modeling was employed to validate the analytical data for the films. Density functional theory (DFT) at B3LYB/ Lanl2DZ level of theory was used to study the effect of addition of ZnO and PVDF on the electronic properties of GO sheet. Total dipole moment
(TDM), HOMO/LUMO energy gap, and molecular electrostatic potential (MESP) are used to investigate changes in the electronic characteristics of the investigated structures. The results reveal that the interaction with ZnO and PVDF increased TDM, decreased the HOMO/LUMO energy gap, and increased reactivity (electro-negativity) for the structures under consideration. Moreover, TDM results confirmed the formation of hydrogen bonding between PVDF and the nanocomposite under study which confirms the FTIR results. Additionally, molecular modeling results are in good agreement with that of UV-Vis-NIR optical spectroscopy as the HOMO/LUMO energy gap decreased and changed with changing the active side of interaction. Accordingly, the application of the prepared polymer nanocomposite was studied by using a gas chamber to expose the polymer nanocomposite film to the toxic gas and measuring the resistance as gas sensor and also studied theoretically.
The application of the prepared polymer nanocomposite films as gas sensor:
According to the experimental and theoretical result, the forth film with the higher concentration of nanocomposite GO/ZnO has the perfect properties to use as gas sensor material. The gas chamber contains the toxic gas, drop-sense to carry out the sensing material and the digital multi-meter to measuring the resistance. The sensing material exposed to gas at different time, the resistance decrease with increasing time.