الفهرس 
INTRODUCTION
EXPERIMENTAL WORKOnly 14 pages are availabe for public view
Abstract
This thesis involves preparation of poly (vinyl chloride) nanocomposites with different contents and types of nanofillers via solution casting technique. Modified Egyptian bentonite with octadecylamine chloride (ODACl), sodium salts of adipic and sebacic dicarboxylic acid were used as filler materials for PVC. Metal oxides nanoparticles (i.e. Fe2O3, ZnO and TiO2) and multiwall carbon nanotubes (MWCNTs) as well as its decorated form (MWCNTs-Ag) were also used and evaluated, based on the obtained results, for using as an effective antibacterial agents in protection and packing of food as well as in medical and healthy applications.
The thesis includes three main sections:
The first section concerned with the introduction, which deals with
1.1. Polymer nanocomposites
1.1.1. Nanocomposites classification
1.1.2. Synthesis of polymer nanocomposites
1.1.3. characterizations of polymer nanocomposites
1.1.4. Properties of polymer nanocomposites
1.2. Layered silicate
1.2.1. Structure and characterization of layered silicates
1.2.2. Organic modification of layered silicates
1.2.3. Polymer layered silicate nanocomposite types
1.3. Inorganic nanofillers
1.3.1. Metal oxide nanoparticles NPs
1.3.1.1. Fe2O3 NPs
1.3.1.2. ZnO NPs
1.3.1.3. TiO2 NPs
1.4. Tube like filler
1.4.1. Carbon nanotubes
1.4.2. Decorated Carbon nanotubes
1.5. Literature survey on poly (vinyl chloride) nanocomposites
1.5.1. Poly (vinyl chloride) nanocomposites based on layered …………silicate
1.5.2. Poly (vinyl chloride) nanocomposites based on metal oxides ………...nanoparticles NPs
1.5.3. Poly (vinyl chloride) nanocomposites based on carbon ………...nanotubes
1.6. Poly (vinyl chloride) nanocomposites applications
The second section includes the experimental part which deals with the used chemicals and their specifications as well as solution casting method for preparation PVC nanocomposites. This section also deals with the analyses and test methods for characterization of the prepared nanocomposites as indicated below:
1- X-ray diffraction (XRD)
2- Energy dispersed X-ray (EDX)
3- Transmission electron microscope(TEM)
4- Fourier transform infrared measurements.
5- Scanning electron microscope(SEM)
6- Raman spectroscopy
7- Dynamic mechanical analysis(i.e. storage modulus, loss modulus and loss factor tan δ)
8- Mechanical properties (i.e. tensile strength, Young’s modulus and elongation at break).
9- Thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA).
10- Dielectric properties (i.e. dielectric constant, dielectric loss and conductivity term)
11- Antimicrobial activity against Gram-positive bacteria(i.e. (Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 35556) and Gram -negative bacteria ( i.e. Escherichia coli ATCC 23282 and Pseudomonas aeruginosa ATCC 10145)
The third section concerned with the obtained results and their discussion based on the effect of filler type and content in comparison to unfilled PVC.
First, for PVC /clay nanocomposites with different modifier clay contents (i.e 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0wt %).
XRD results indicated that: For PVC nanocomposites with ODA and Na- sebacate organoclay at 3wt%, no diffraction peak appears at the testing scale that is from 0o to 10o which indicates complete exfoliation as compared with Na-adipate organoclay. This result is expected because the basal spacing of clay modified with Na sebacate was greater than that treated by Na-adipate.
The nanostructure of the silicate layer in the ODA-clay and sebacate - clay (3wt%) in PVC matrix was observed by using (TEM) as compared with sebacate organoclay (6wt%)where large agglomerations of the sebacate layers were formed leading to heterogeneous dispersion at 6wt%.
FTIR data of the prepared PVC /nanocomposites were similar to unfilled PVC.
The mechanical properties (i.e tensile strength, Young’s modulus and elongation at break ) of the prepared PVC/ nanocomposites, showed
an enhancement on increasing the modified clay content up to 3wt% with a slight increase in elongation at break. Increasing the modified clay content more than 3wt% and up to 6wt%, the tensile strength and Young’s modulus as well as elongation at break decreased. The carboxylated acid salts possess stronger polarity than octadecyl amine which could enhance the interfacial interaction between the layered silicate and PVC matrix. This may be the reason for the difference in the mechanical properties of these two types of PVC/bentonite nanocomposite.
The thermal decomposition was studied by using TGA and DTGA techniques for the prepared PVC nanocomposites at 3wt% and 6wt% organoclay content in comparison with unfilled PVC. The test results showed that carboxylated pretreated clay at 3wt% maximize the dehydrochlorinated temperature of PVC matrix and char residue at 800oC in comparison to ODA pretreated clay at the same weight percentages. While the opposite behavior (i.e. a degradation at a lower temperature with a lower residue) was observed at 6wt%.
Second for PVC/ metal oxide nanoparticles NPs composites
For metal oxide (i.e. Fe2O3, ZnO and TiO2) NPs:
EDX showed the presence of Fe, Zn and Ti beside the presence of oxygen.
XRD pattern showed that Fe2O3 is crystalline and all peaks can be assigned to pure hematite α - Fe2O3 .For ZnO and TiO2NPs, the XRD pattern showed wurtzite hexagonal and anatase crystalline structures for ZnO and TiO2.
The nanostructure of the metal oxide NPs was studied using TEM. For Fe2O3 NPs, the average particle size was about 20-85 nm, in
comparison to ZnO and TiO2 with average sizes of 11-28 nm and 12-30nm, respectively. It is clear that ZnO NPs are smaller in size in comparison to TiO2 and Fe2O3.
The Raman results demonstrated that Fe2O3 NPs belong to the hematite α- Fe2O3. While ZnO and TiO2 NPs belong to wurtzite hexagonal an anatase phase respectively.
For PVC/ metal oxide NPs composites with different contents (i.e. 2.0, 5.0. 10.0 and 15.0 wt%) the obtained results reveal that: For PVC nanocomposites with metal oxide NPs at 15 wt%, XRD analysis indicated that PVC has no effect on the crystal structure of these metal oxide NPs. In other words, with PVC, there is no any changes in the hematite, wurtzite and anatase crystal like structure of Fe2O3, ZnO and TiO2 NPs, respectively.
Raman spectra of the prepared composite films, indicated that there is no new band or shift in the Raman spectra of metal oxide NPs in PVC, suggesting no chemical bonding between metal oxide NPs and pure PVC, just a physical interaction forming admixture of both PVC and metal oxides NPs.
By using the scanning electron microscope (SEM), the surface morphology of PVC/ metal oxide NPs at 10wt% indicated fine dispersion of these metal oxides NPs in PVC matrix, in comparison to agglomeration formation of these NPs at 15wt%.
Dynamic mechanical analysis (i.e. storage modulus, loss modulus and loss factor tan δ). It was found that storage modulus and loss modulus of film samples increased with increasing NPs content up to 10wt%, while loss factor tan decreased shifting to higher Tg values in comparison to film samples with 15wt% metal oxides NPs and Pure PVC.
Thermogravimetric analysis indicated that with increasing Fe2O3, TiO2 NPs contents up to 10wt% into PVC matrix, the thermal stability of PVC nanocomposites was increased with increasing the char yield and consequently limiting oxygen index. On the other hand, film samples with ZnO NPs exhibited the opposite behavior.
The dielectrical properties (Ɛ` and Ɛ``) of the prepared PVC/metal oxides NPs composites, at various frequencies and at room temperature 25 °C exhibited conductive properties as they have the highest (Ɛ` and Ɛ``) with increasing the metal oxides NPs content up to 15 wt %. The increase in Ɛ` and Ɛ`` was pronounced at lower frequency when compared to unfilled PVC. At fixed frequency, (i.e.100 HZ), the increase in Ɛ` and Ɛ`` with filler loading follow the order: TiO2>Fe2O3>ZnO in PVC matrix.
The electrical conductivity (σ) were found to be in order of 10-13 for ZnO while it is in the order of 10-11 for Fe2O3 and TiO2, suggesting such composites to be used in antistatic applications. Since the required range for such application is 10-9-10-14Ω-1cm-1.
Antibacterial activity of the prepared film samples with different loadings of metal oxides NPs have been performed and compared with unfilled PVC. It was found that the prepared samples have an inhibition efficiency on both bacteria types (i.e. Gram- positive and Gram- negative) at low concentrations which was increased with increasing metal oxide NPs content up to 10wt%. Thus, the increase in antibacterial activity follow the order: ZnO>TiO2>Fe2O3 as an inhibitor on Gram- positive bacteria and TiO2>ZnO>Fe2O3 as an inhibitor on Gram- negative bacteria. Thus, TiO2 had better antibacterial activity against Gram- negative bacteria, in comparison to ZnO and Fe2O3.
Finally, the results suggested that metal oxides composites improved the antibacterial activity of PVC and can be used as an effective antibacterial agents to protect agriculture and food also in medicalas well as healthy applications.
Third, for PVC/ multiwall carbon nanotubes MWCNTs composites
First carboxylation of CNTs with HNO3 acid and consequently decoration of CNTs surface with Ag NPs by reduction of aqueous silver nitrate with N,N dimethyl formamide. Then, PVC composites with pure CNTs and CNTs-Ag were prepared by solvent casting technique for the purpose of comparison. For PVC/ CNTs and CNTs –Ag composites with different contents (I.e. 0.5, 1.0, 3.0, 5.0 wt%) the obtained results reflected that:
XRD analysis of CNTs-Ag confirmed the decoration of CNTs surface by the appearance of the distinct diffraction peaks of the crystalline phase of silver. For PVC/CNTs-Ag, the XRD pattern showed the PVC transmutation from semi crystalline to crystalline because of the presence Ag NPs on CNTs surface.
The nanostructure of pristine CNTs and CNTs-Ag was observed by TEM, to be ~25-30 nm and 7-16 nm, respectively. Moreover, a large number of Ag NPs were anchored to CNTs surface with quasi- spherical morphology after the decoration process.
Raman spectrum of the prepared CNTs-Ag, suggested the presence of chemical interaction between AgNPs and acid carboxylate groups on CNTs surface, confirming TEM image of CNTs-Ag sample. For PVC/CNTs-Ag, all the Raman spectra of CNTs-Ag overlapped the region of PVC, confirmed the formation of these composites.
Dynamic mechanical analysis (i.e. storage modulus, loss modulus and loss factor tan δ). The results indicate that, storage modulus and loss modulus increased with increasing CNTs or CNTS-Ag content up to 5.0 wt %. Higher storage modulus and loss modulus values and smaller tan δ with shifting to higher Tg values were obtained for composites containing CNTs-Ag in comparison to those with CNTs.
Thermogravimetric analysis indicated that increasing CNTs and CNTS-Ag contents in PVC matrix up to 5.0 wt% increased PVC thermal stability up to 450 and 457 OC, respectively. Thus, the data reflected lower flammability of composites containing CNTs-Ag in comparison to those with CNTs based on their greater char yield and calculated limiting oxygen index.
The dialectical properties (Ɛ` and Ɛ``) of the prepared PVC/CNTs composites before and after CNTs decoration with AgNPs, at various frequencies and room temperature 25 °C, indicated that Ɛ` and Ɛ`` increase with increasing filler loading up to 15 wt %. Also, Ɛ` and Ɛ ``raised sharply at lower frequency in comparison to unfilled PVC. At fixed frequency (i.e. 100 HZ), the increase in Ɛ` and Ɛ`` with filler loading follow the order: PVC/CNTs-Ag>PVC/CNTs
This is because the electrical conductivity of Ag is much higher than that of CNTs. Addition of CNTs or CNTs-Ag increased the electrical conductivity of PVC from 10-13Ω-1 cm-1 to 10-9Ω-1 cm-1. By increasing CNTs content up to 5.0 wt %, σ increased to be 10-8. Beyond 5 wt %, a monotonously increase in σ was detected. Decoration of CNTs surface with Ag increased the electrical conductivity of PVC but with the same order of magnitude (i.e. 10-8Ω-1 cm-1). This value is enough to achieve the electrostatic dissipation behavior, (10-5 - 10-9Ω-1 cm-1).
Antibacterial activity results for PVC/CNTs and PVC/CNTs-Ag film samples suggested that Ag NPs deposition significantly improved the antimicrobial efficiency of CNTs in PVC against both types of bacteria. This attributed to the release of Ag ions from the nanocomposites. Thus, these composites monohybrids may be applicable for disinfecting coating (i.e. antimicrobial coating) during water treatment, filtration and purification process.