Ibtisam Yahya Abdullah

Polymer-ZnO nanocomposites foils and thin films for UV protection

The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.

Investigation of energy band gap in polymer/ZnO nanocomposites

Polymers/ZnO nanocomposites have been receiving great interest due to their wide range of applications in optical devices. So, there is an essential need to enhance their optical properties. In this work, nanocomposites of four types of polymer and ZnO nanoparticles have been prepared as flexiable foil by using the casting method. Poly (methyl methacrylate) (PMMA), poly (vinylidene fluoride) (PVDF), polyvinyl alcohol (PVA), and polystyrene (PS) are used as polymer matrix while different concentrations of ZnO nanoparticles are used as filler. The analysis of energy dispersive X-ray (EDX) is satisfied of the high purity of as-prepared samples. UV-visible transmittance spectra have shown low transmittance in UV region which is inversely proportional with the concentration of ZnO nanoparticles. Linear absorption coefficient (α) has shown the presence of absorption edges. The energy gap is calculated, it is noticed that the optical band gap of all nanocomposites are red shifted. The values of the energy gap for all samples decreased with the increase of the weight percentage of ZnO nanoparticles in nanocomposites. However, the decrement in nanocomposites samples is different.

Effect of annealing process on the phase formation in poly(vinylidene fluoride) thin films

This work reports the initial study on the effect of annealing process on the crystalline phase of poly(vinylidene fluoride) (PVDF) thin film. PVDF powder was dissolved in N,N-dimethylformamide before spin-coated onto a glass substrate to form a film. The films were annealed at 30°C, 90°C and 110°C for 5 hrs. The crystalline phase of the powder PVDF as received was investigated by using XRD and FTIR techniques. Moreover, the crystalline phases of thin films after annealing were investigated by using the same techniques. XRD analysis showed that in powder form PVDF exists in α-phase. Each annealed PVDF thin films exhibited identical formation of three-phases material namely γ (as major phase) while α and β phases as the minor phases. The FTIR analysis showed that the powder form of PVDF exists in α and β phases. FTIR measurement further confirmed the XRD results implying that the annealing process has no significant effect on the phase formation in PVDF films.

Influence of the spinning rate on the β-phase formation in poly(vinylidene fluoride) (PVDF) films

In this work, the effect of rotational speed on the β-phase formation in PVDF films is investigated. The rotational speeds use in this work are 500, 1000, 2000 and 4000 rpm. All films are left to dry at room temperature. FTIR and XRD technique are employed to determine the phase formation while SEM is used to investigate the morphology of the films. The FTIR and XRD measurements confirm that the main phase formed in all PVDF films is β-phase. However, the β-phase contents vary with the spinning rate and the highest content is observed approximately 83% for 500 rpm film. SEM micrographs show the surface of all samples is porous structure and rough.In this work, the effect of rotational speed on the β-phase formation in PVDF films is investigated. The rotational speeds use in this work are 500, 1000, 2000 and 4000 rpm. All films are left to dry at room temperature. FTIR and XRD technique are employed to determine the phase formation while SEM is used to investigate the morphology of the films. The FTIR and XRD measurements confirm that the main phase formed in all PVDF films is β-phase. However, the β-phase contents vary with the spinning rate and the highest content is observed approximately 83% for 500 rpm film. SEM micrographs show the surface of all samples is porous structure and rough.