الفهرس 
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Abstract
Preparation and characterization of Polymer-Nanoclay Composite Materials”
Thesis submitted to the Faculty of Science, Alexandria University, Chemistry Department, In partial fulfilment of the requirementsFor the degree of M.Sc in (Chemistry)
Submitted By: MoustafaMohamed Salah El Dine ZakiZagho
The present thesis is divided into six chapters. Chapter I: Introduction This chapter presents a general view of polymers. It alsoprovides a brief account of nanomaterials including their definitions, importance andclassifications. The chapterincludes a study of polymer nanocompositeswhich are critically important from both the academic and industrial point of views Polymers are hardly used in their pure form in industrial applications; so they are vastly modified with additives like nanometric inorganic compounds. By inserting the nanometric inorganic compounds, the properties of the polymers will be improved resulting in a wide scope of industrial applications depending upon the inorganic material present in the polymers. One of the used inorganic materials is smectite clay which consists of layers of silicates. Polymer nanoclay composites have novel characteristics like thermal, mechanical, flame retardant and corrosion protection properties of polymers at low clay loading. This chapter also summarizes the proposedaim of the research in this thesis Chapter II: Review of Literature This includes the historical view of polymer nanocomposites. Moreover the chapter presents the structure of montmorillonite (MMT), poly(vinyl alcohol) (PVA),nanocomposites and PVA/MMT nanocomposites. There are three main types of composites which are: non mixing composites, intercalated structures and exfoliated or delaminated structures. Thenanocomposites can be characterized by a variety of techniques including X-ray diffraction (XRD), Nano Scanning Electron Microscopy (NSEM), Fourier-Transformation infrared (FTIR), X-ray Fluorescence Spectrometer (XRF), Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DCS) and mechanical strength. XRD is most commonly used technique to study the nanocomposite structure easily.
Chapter III: Experimental
It discloses the details of the experimental techniques implemented in this study; such as chemicals, materials and procedures for synthesis of powders and films of different polymer nanoclay composites namely PVA/ Na-rich MMT, PVA/ Cloisite® 20A, PVA/ Cloisite® 10A and PVA/ Cloisite® 93A nanocomposites. The analytical tools used in this study include XRD, NSEM, FTIR, XRF, TGA, DCS and mechanical strength. The XRD analysis and SEM observations were used to study the dispersion and exfoliation of nanoparticles. The FTIR and XRF analyses are used to identify the composition of the nanocomposites. TGA and DCS analyses were used to study the thermal stability of the nanocomposites. The mechanical properties of nanocomposites were measured using Tensile Tester Chapter IV: Results and Discussion In this research, the study on different PVA silicate nanocomposites(such as PVA/ Na-rich MMT, PVA/ Cloisite® 20A, PVA/ Cloisite® 10A, PVA/ Cloisite® 93A nanocomposites) has been presented. The intercalation with Na-rich MMT, Cloisite® 20A and Cloisite® 93A was evidenced fromXRD which showed enlargement of the basal spacing. For instance, in case of 5wt% clay loading, the observed enlargement was from 12 Å to 16 Å , 23 Å to 35 Å and 26 Å to 39 Å for (pure Na-rich MMT and PVA/ Na-rich MMT),(pure Cloisite® 20A and PVA/ Cloisite® 20A) and (pure Cloisite® 93A and PVA/ Cloisite® 93A nanocomposites) pairs respectively.NSEM also showed that the Na-rich MMT, Cloisite® 20A and Cloisite® 39A palettes were homogeneously dispersed within the PVA gallery, presumably, due to intercalation from FTIR spectra, we concluded that whenever the clay loading increases, the intensities of the organophilic clay bands become stronger for PCN materials. XRF spectrum of pure montmorillonite shows that Siatoms have the highest element ratio in the MMT components. There are other elements with significant ratios such as Al, Mg, O, Ca and Fe.
Furthermore, the TGA results showed shift in melting point, Tm towards higher temperatures upon blending PVA with Na-rich MMT, Cloisite® 20A and Cloisite® 39A. Moreover, the DSC results showed shift in the glass transition temperature, Tg, towards higher degrees upon blending PVA with these types of clays.These shifts confirm the thermal stability of theproduced nanocomposites. Intercalation markedly affected both Young’s modulus and the extent of elongation of PVA/ Na-rich MMT, PVA/ Cloisite® 20A, PVA/ Cloisite® 93A nanocomposites. Regarding the mechanical properties, the following conclusions could be stated: Young’s modulus and tensile stress increase with the loading of the clays. The opposite results that are seen for clay loading above 2wt% in case of Cloisite® 20A and 3wt% in case of Cloisite® 93A are due to the agglomeration of nanoparticles at higher particle loading and then formation of micro voids. The fracture toughness increases with the increasing of the clay loading to reach finally a steady state.
On the other hand,the XRD of PVA/ Cloisite® 10A nanocomposite did not show significant shift of any of the clay peaks and the NSEM image has shown aggregation of the clay platelets and poor distribution within the polymer matrix which confirm that no intercalation occurs for this nanocomposite.Chapter V: Conclusions This chapter outlines our findings, conclusions and recommendations based on the collected results from this study. Chapter VI: References A list of 130 references was cited at the end of this thesis.