الفهرس 
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Abstract
The work of the present Ph. D. Thesis aimed to improve and enhance the properties of polypropylene such as antibacterial activity, UV protection, antistatic property and electrical conductivity. Polypropylene have been loaded with different nanomaterials namely, cuprous oxide (Cu2O), silver (Ag) and aluminum oxide (Al2O3) and their mixtures to produce multifunctional properties using different methods.
Polypropylene has many disadvantages such as very low electrical conductivity and poor UV protection. In addition to its hydrophobicity and the tendency to accumulate electrostatic charges.
In this study, PP was modified with various nanomaterials to enhance its properties and upgrade its performance and added value as follows:
1. In situ preparation of cuprous oxide microparticles onto nonwoven polypropylene fabric (PP/Cu2O) by pad-dry-cure method.
2. In situ preparation of mixtures of (cuprous oxide/silver) nanoparticles onto nonwoven polypropylene fabric (PP/Cu2O/Ag) by pad-dry-cure method.
3. Preparation of polypropylene/silver/aluminum oxide nanocomposite films (PP/Ag/ Al2O3) by compression molding technique.
The analysis and evaluation for the modification of PP were performed using the following:
Scanning electron microscope (SEM) and Energy dispersive X-ray spectroscopy (EDX)
X-ray diffraction (XRD)
Fourier transform infrared spectroscopy (FTIR)
Thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG)
Antimicrobial activity
Ultraviolet protection factor (UPF)
Electrical conductivity measurement
Electrostatic charge measurement
Color measurements
Contact angle measurement
Conclusion
1. In situ preparation of cuprous oxide microparticles onto nonwoven polypropylene fabric (PP/Cu2O)
Nonwoven PP fabrics were modified by pad-dry-cure method using cuprous oxide microparticles. They were in situ synthesized onto PP fabric as a result of the reduction of CuSO4.5H2O in alkaline medium using glucose as a reducing agent. The reduction reaction of CuSO4.5H2O is illustrated in Scheme 3.
Scheme 3. Synthesis of Cu2O by chemical reduction of CuSO4
The morphology of PP fabric was studied by SEM and EDX. Cu2O microparticles were observed onto treated PP surface. The deposited microparticles have uniformly cubic shape with average particle size 0.6-0.8 μm. EDX spectrum of PP/Cu2O clearly confirmed the presence of copper and oxygen elements in the sample.
The treated fabric was characterized by XRD to detect and confirm the formation of Cu2O microparticles onto PP. The characteristic peaks corresponding to Cu2O were noticed at 2θ [36.5°, 42.4°, 61.5° and 73.7°].
After the deposition of Cu2O microparticles, PP fabric showed antimicrobial effect towards gram positive bacteria (S. aureus), gram negative bacteria (E. coli) and fungi Candida albicans (C. albicans). The maximum bacterial reduction obtained was 88 % against S. aureus. Also, the presence of Cu2O microparticles enhanced the UV blocking property of PP fabric and UPF value has raised from 1.3 to 39.3 (classified as very good protection). PP fabric has acquired a brown brick color due to the deposition of Cu2O microparticles.
2. In situ preparation of mixtures of (cuprous oxide/silver) nanoparticles onto nonwoven polypropylene fabric (PP/Cu2O/Ag)
In situ synthesis of mixtures of Cu2O/Ag NPs onto nonwoven PP fabrics was carried out using pad-dry-cure method. Mixtures of CuSO4.5H2O and AgNO3 with three different mixing ratios [75:25, 50:50 and 25:75] were reduced by glucose in basic medium. Furthermore, PP fabric was separately treated with CuSO4.5H2O and AgNO3. The reduction reaction of CuSO4.5H2O and AgNO3 is depicted in Scheme 4.
Scheme 4. Synthesis of Cu2O and Ag by chemical reduction of CuSO4 and AgNO3
Surface morphology of untreated and treated PP fabrics was observed by SEM. The synthesis and deposition of Cu2O, Ag and Cu2O/Ag NPs onto treated PP was confirmed. The formed Cu2O and Ag NPs have cubic and spherical shapes, respectively. EDX spectrum has revealed the presence of copper, silver and oxygen elements onto PP fabrics after treatment. The formed particles have average particle size of approximately 250 nm for Cu2O and < 100 nm for Ag.
XRD demonstrated the presence of diffraction peaks at 2θ [36.5°, 42.4°, 61.5° and 73.6°] and 2θ [38.6°, 44.5°, 64°, 77.8°] which could be attributed to the presence of Cu2O and Ag NPs onto the modified fabrics, respectively.
The thermal stability of untreated and treated PP fabrics was investigated using TGA and DTG analysis. The thermal decomposition of untreated and treated PP occurred in a single one step. Sample (PP/Ag) showed decrease in thermal stability unlike the other treated fabrics.
The performance of PP fabric was assessed before and after treatment. It was found that all treated samples showed remarkable bacteriostatic activity against both S. aureus and E. coli. The treated samples achieved percentage bacterial inhibition ranged from 82-100 %. Interestingly, the incorporation of mixtures of Cu2O and Ag nanoparticles has synergistically promote the UV protection of PP. UPF value has increased from 42.7 for sample [PP/ Cu2O/Ag (25:75)] to 50+ for sample [PP/ Cu2O/Ag (75:25)].
3. Preparation of polypropylene/silver/aluminum oxide nanocomposite films (PP/Ag/Al2O3)
Polypropylene was modified with Ag and Al2O3 nanoparticles and they have been added individually or as a mixture. PP nanocomposites films were prepared using compression molding technique. Firstly, PP pellets were dissolved in xylene followed by the addition of Ag, Al2O3 and mixtures of Ag/Al2O3 nanoparticles by the ratio of 5, 10 and 20 % of weight. After evaporation of the solvent, the desired PP nanocomposite in the powder form was obtained. Finally, PP nanocomposites were hot pressed at 195 °C under pressure to obtain thin films of 0.21 mm. The properties of the prepared PP nanocomposites were investigated to evaluate their performance compared with the pristine PP.
The surface of the pristine PP was studied by SEM and it appeared smooth. The nanoparticles of Ag, Al2O3 and Ag/Al2O3 were observed on the surface of PP and embedded into the PP film. Nanoparticles were uniformly distributed in case of using low concentration of nanoparticles (5 %). Ag and Al2O3 NPs have spherical shapes with very small particle size of approximately < 50 nm. By increasing the concentration of the nanofiller into PP matrix, agglomerated clusters were noticed.
EDX and XRD analysis confirmed the presence of Ag and Al2O3 in the prepared PP nanocomposites. EDX spectrum indicated the presence of silver, Aluminum and oxygen elements. The distinguished peaks of Ag and Al2O3 were detected in XRD at 2θ [38°, 44°, 64°, 77°] and 2θ [37°, 43°, 66°], respectively.
The antimicrobial tests clearly proved that the fabricated PP nanocomposites exhibited better antimicrobial activity (70-90 %) compared to the pristine PP. Also, the inhibitory effect improved with increasing the concentration of Ag, Al2O3 and Ag/Al2O3 nanoparticles in PP matrix. A distinct reduction in viability of all tested microorganisms (>90 %) was observed for sample Ag3 [PP/Ag (20 %)].
PP/Ag/Al2O3 and PP/Ag nanocomposites showed excellent UV protection compared with pristine PP and PP/Al2O3. The results of electrical conductivity measurement showed improvement in the electrical property of PP nanocomposites. Also, it was noticed that the electrostatic charges accumulated onto pristine PP decreased after incorporation of Ag, Al2O3 and Ag/Al2O3 nanoparticles.
from the above results, the treated nonwoven PP fabrics and the prepared PP nanocomposite films could be used in applications such as, health care products, filters, linings, carpets, packaging and geotextiles.