Preparation of Polycarbonate-ZnO Nanocomposite Films: Surface Investigation after UV Irradiation

Polycarbonate (PC)-ZnO films with different percentages of ZnO were prepared by a solution stirring technique and subjected to ultraviolet (UV; λ = 254 nm) irradiation. Structural parameters of the samples and the effects of UV irradiation on the surface properties of the PC and PC-ZnO nanocomposites were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), water contact angle (WCA) measurements, and a Vickers microhardness (HV) tester. The XRD patterns of the nanocomposite films were found to show an increase in crystallinity with the increasing ZnO nanoparticles percentage. The WCA was found to be reduced from 90° to 17° after 15 h of UV irradiation, which could be ascribed to the oxidation of the surface of the samples during the irradiation and exposure of the ZnO nanoparticles, a result that is also supported by the obtained XPS data. The microhardness value of the PC-ZnO films including 30 wt.% ZnO enhanced considerably after UV radiation, which can also be attributed to the exposition of the ZnO nanoparticles after photodegradation of the PC superficial layer of the nanocomposite films

<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA" lang="EN-US">Mechanical properties of polycarbonate-TiO₂ nanocomposite film</span>

241-250<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:fa"="" lang="EN-US">The mechanical properties of polycarbonate-TiO2 nanocomposite films have been investigated by conducting tensile tests and hardness measurements. The elastic modulus of the composite increased with increasing the weight fraction of particle, especially over 0.8 wt%. The X-ray diffraction results (XRD) show that the increase of strength is accompanied by decrease in intensity of amorphous polycarbonate and appearance of the peak of anatase. The theoretical models proposed by Guths-Smallwood, Einstein, Kerner and Cohen-Ishai are used but only the first model provided better results and is modified for the studied composite. The law of mixture is used to calculate the contribution coefficients of the constituents and the results of this modeling provided the acceptable precision. Peak stress and strain has been increased with increasing TiO2 nanoparticles content while the stress and strain corresponding to the fracture point did in opposite. It is attributed to the influence of particles on the plastic weakening of the composite.</span

Mechanical properties of polycarbonate-TiO2 nanocomposite film

The mechanical properties of polycarbonate-TiO2 nanocomposite films have been investigated by conducting tensile tests and hardness measurements. The elastic modulus of the composite increased with increasing the weight fraction of particle, especially over 0.8 wt%. The X-ray diffraction results (XRD) show that the increase of strength is accompanied by decrease in intensity of amorphous polycarbonate and appearance of the peak of anatase. The theoretical models proposed by Guths-Smallwood, Einstein, Kerner and Cohen-Ishai are used but only the first model provided better results and is modified for the studied composite. The law of mixture is used to calculate the contribution coefficients of the constituents and the results of this modeling provided the acceptable precision. Peak stress and strain has been increased with increasing TiO2 nanoparticles content while the stress and strain corresponding to the fracture point did in opposite. It is attributed to the influence of particles on the plastic weakening of the composite

Efficient degradation of environmental contaminants using Pd-RGO nanocomposite as a retrievable catalyst

Baran, Talat ( Aksaray, Yazar )Abstract: Pd nanoparticles (NPs)/reduced graphene oxide (RGO) nanocomposite was prepared in a one-pot process by using Euphorbia stenoclada extract as antioxidant media in the absence of any surfactant, dangerous reactants or using external energy input. Catalytic potential of the fabricated Pd-RGO nanocomposite was examined for the degradation of environmental contaminants including Cr(VI), 4-nitrophenol (4-NP), Congo red (CR), methylene blue (MB) and methyl orange (MO). The Pd-RGO nanocomposite has been thoroughly characterized by employing X-ray diffraction, UV–Vis and TEM studies. Furthermore, recyclability and reusability aspects of the nanocomposite were monitored for multiple uses without much change in catalytic activity. Graphic abstract: [Figure not available: see fulltext.]

Characteristics of PVDF Membranes Irradiated by Electron Beam

Polyvinylidene fluoride (PVDF) membranes were exposed vertically to a high energy electron beam (EB) in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphologies were studied by Scanning Electron Microscopy (SEM) and showed some changes in the pore size. Thermogravimetric (TGA) analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR) showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane

Sandwich-type double-layer piezoelectric nanogenerators based on one- and two-dimensional ZnO nanostructures with improved output performance

Abstract Piezoelectric nanogenerators (PENGs) have attracted great interest owing to their broad range application in environmental mechanical energy harvesting to power small electronic devices. In this study, novel flexible and high-performance double-layer sandwich-type PENGs based on one-dimensional (1-D) and two-dimensional (2-D) zinc oxide (ZnO) nanostructures and Ni foam as the middle layer have been developed. The morphology and structure of 1- and 2-D ZnO nanostructures have been studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). To investigate the effect of structural design on the piezoelectric performance, single-layer PENGs were also fabricated. The piezoelectric output of all prepared PENGs were evaluated under different human impacts at various forces and frequencies. The double-layer designed PENGs showed a two times larger voltage output compared to the single-layer PENGs, and the use of Ni foam as middle-layer and of 2-D ZnO nanosheets (compared to 1-D nanorods) was also found to increase the performance of the designed PENGs. The working mechanism of the prepared PENGs is also discussed. The design of nanogenerators as double-layer sandwich structures instead of two integrated single-layer devices reduces the overall preparation time and processing steps and enhances their output performance, thus opening the gate for widening their practical applications

Photocatalytic degradation of volatile chlorinated organic compounds with ozone addition

The decomposition of hydrocarbons using combined advanced oxidation methods is largely considered owing to abundant production of OH radicals and the potential economic advantages. In this study, the synergetic effect of ozonation on photocatalytic oxidation of chloroform and chlorobenzene over expanded graphite-TiO2&ZnO Nano composite was investigated. The effect of introduced ozone concentration and residence time was also examined on removal efficiency. The results showed that the removal efficiency was significantly enhanced by the combined system resulting from the additional oxidation process causing active species to be increased. Increasing the introduced ozone concentration which generates more reactive compounds had a greater effect on the removal efficiency than that of residence time. However, from the mineralization point of view, the residence time had a dominant effect, and the selectivity towards CO2 was dramatically declined when the flow rate increased. Based on these results, the combined system is preferred due to higher removal efficiency and complete mineralization