Photodegradation of low-density polyethylene with prooxidant and photocatalyst

Low-density polyethylene (LDPE) composite films with trisilver phosphate (Ag₃PO₄) and cadmium selenide (CdSe) particles as photocatalysts and manganese stearate as prooxidant were prepared. The film samples were irradiated under UV and visible light and their photodegradation were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The carbonyl index of the photocatalyst containing samples was very higher than the pure irradiated LDPE and even prooxidant containing film. The morphologies of the irradiated composite films were completely changed and had many cavities and cracks. The thermal stability of the composites was very lower than the pure polyethylene. However the crystallinity of the LDPE films with photocatalysts was enhanced contrarily the LDPE film with manganese stearate. Generally the results showed that the combination of the prooxidant with photocatalyst have synergistic effect on the photodegradation of the LDPE and can be used to accelerate the degradation of the polyethylene films.     

Silane Modification of Carbon Nanotubes and Preparation of Silane Cross‐Linked LLDPE/MWCNT Nanocomposites

The objective of this study is to investigate the effects of carbon nanotube (CNT) content, surface modification, and silane cross‐linking on mechanical and electrical properties of linear low‐density polyethylene/multiwall CNT nanocomposites. CNTs were functionalized by vinyltriethoxysilane to incorporate the ─O─C2H5 functional groups and were melt‐blended with polyethylene. Silane‐grafted polyethylene was then moisture cross‐linked. Silanization of CNT was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and EDX analysis. Hot‐set test results showed that silane cross‐linking of polyethylene and incorporation of modified CNTs into polyethylene led to an increase in cross‐linking density and the number of entanglements resulting in a decrease in elongation. It was found that the addition of pristine multiwall carbon nanotubes (MWCNTs) and functionalized MWCNTs does not affect silane cross‐linking density. Silane modification resulted in a stronger adhesion of the silane cross‐linked LLDPE to silanized MWCNTs according to scanning electron microscopy micrographs. Additionally, the electrical tests revealed that the silane modification of CNTs results in an improvement in electrical properties of nanocomposites, while silane cross‐linking will not have an effect on electrical properties. Rheological properties of MWCNT/LLDPE nanocomposites have been studied thoroughly and have been discussed in this study. Moreover, according to TGA test results, modification of the MWCNTs led to a better dispersion of them in the LLDPE matrix and consequently resulted in an improvement in thermal properties of the nanocomposites. Crystallinity and melting properties of the nanocomposites have been evaluated in detail using DSC analysis. J. VINYL ADDIT. TECHNOL., 26:113–126, 2020. © 2019 Society of Plastics Engineers     

Features of the Structure and Properties of Radiation Vulcanizates Based on Blends of Polybutadiene and Ethylene‐Propylene Diene Rubber

Polybutadiene rubber (BR) was blended with ethylene‐propylene diene (EPDM) rubber on rubber mill with different weight ratios (100/0‐70/30‐50/50‐30/70‐0‐100), then application of gamma rays at different irradiation doses from 25 up to 150 kGy to induce crosslinking. Mechanical, physio‐chemical, and characterization of prepared blends are to be followed up as functions of the blend composition and the radiation absorbed dose. Mechanical properties like tensile strength (TS), elongation at break (E_b), and tensile modulus (M₁₀₀) were increased with increasing content of EPDM in blend composition. On the other hand, TS and M₁₀₀ increased with radiation dose, whereas the value of E_b decreased with radiation dose. Physico‐chemical properties like gel fraction and volume fraction of rubber in swollen gel (V_r) increased with increasing the content of EPDM rubber in blend formulation while the swelling ratio and soluble fraction decreased with increasing content of EPDM. On the other hand, the V_r increased with radiation dose, whereas the values of soluble fraction and selling ratio (Q) decreased with radiation dose. Fourier transforms‐infrared measurements confirmed the compatibility between BR and EPDM rubber moieties in the blend matrix. J. VINYL ADDIT. TECHNOL., 25:E64–E72, 2019. © 2018 Society of Plastics Engineers     

Effect of Microfluidization Condition on Physicochemical Properties and Inhibitory Activity of Nanoemulsion Loaded with Natural Antibacterial Mixture

The main objective of this study was to investigate the effects of the microfluidic pressure (600–1200 bar) and cycles (2–4) on the inhibitory activity and physicochemical properties of the nanoemulsion loaded with a natural antibacterial mixture (i.e., citral, trans-2-hexen-1-ol, and linalool, 1:1:1 w/w). The current study showed that the microfluidization at 1000 bar for 4 cycles resulted in the most stable antibacterial nanoemulsion with the smallest droplets. In most cases, the cycle had the more significant effect than the pressure on the physicochemical properties of the antibacterial nanoemulsion. The minimal inhibitory concentrations (MICs) for Salmonella Typhi, Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes were 2500, 5000, 1250, and 5000 μg/ml, respectively. In general, the microfluidization condition did not significantly affect the ξ-potential and inhibitory activity of the antibacterial nanoemulsion. The microfluidization at 1350 bar and 3 cycles was the overall optimum preparation condition. There was an insignificant (p?>?0.05) difference between the experimental and predicted optimum point. This verified the adequacy of the response surface models fitted for explaining the properties of antibacterial nanoemulsion as a function of microfluidization condition.     

Study of performance and stability of hole transport layer-free perovskite solar cells with modified electron transport layer

Journal of Materials Science: Materials in Electronics - The electron transport layer (ETL) performs a functional role in the structure of perovskite solar cells (PSCs). Here in this study, various...     

Circularly/Linearly Polarized Low-Profile Plasma Microstrip Antenna for MIMO Applications

Wireless Personal Communications - A polarization reconfigurable square microstrip patch antenna (SMSPA) based on plasma is introduced in this paper. The antenna is designed for mobile...     

In situ synthesis of leucite-based feldspathic dental porcelain with minor kalsilite and Fe2O3 impurities

K-Feldspar was used as a raw material for in situ synthesis of leucite particles by solid-state reaction method. Prior to synthesis of leucite, K-Feldspar was treated by oxalic acid (C₂H₂O₄) to eliminate Fe content. The parameters affecting the structure and amount of Fe in K-Feldspar was investigated to reach an optimal leaching condition. Next, kasilite removal was studied by introducing CaF₂ to the composition of dental porcelain. To synthesis leucite, the prepared materials were heated up to 1450°C for 3 hours until fusion phenomena occurred, then cooled down to 865°C to permit the leucite crystals nucleate and grow. To find out the chemical composition of powder, XRF, EDX, and Atomic absorption spectroscopy were used. Fourier Transform Infrared Spectroscopy and X-Ray Diffractometer and Scanning Electron Microscopy were employed to study the structure of mineral. Spectrophotometry was chosen to analyze whiteness index of powder after acid treatment. Differential Thermal Analysis was employed to determine the crystallization temperature. Results indicated a dramatic decrease in Fe content (0.018%wt) by employing C₂H₂O₄ as a leachant at 50°C. In addition, whiteness index of 91% was achieved through this procedure for raw feldspar. Finally, 1%wt of CaF₂ prevented formation of kalsilite.     

Latent Dirichlet allocation (LDA) and topic modeling: models,applications, a survey

Multimedia Tools and Applications - Topic modeling is one of the most powerful techniques in text mining for data mining, latent data discovery, and finding relationships among data and text...     

Modeling the micro-scale static friction coefficient of the MEMS silicon surfaces affected by Ag and Au deposition using the thermal evaporation method

In different macro-scale applications, regarding what should be done, many of the prepared surfaces are immediately used after machining with no limitation. Since the micro-electromechanical applications have different conditions, their different properties, such as friction and adherence, must be checked. In the present study, using the thermal evaporation method, the silver and gold layers with different thicknesses were deposited on the silicon surfaces widely used in micromechanical systems (e.g. micro-assembly). Thereafter, the effects of the deposition on the geometrical properties of the surfaces were studied. Also, the effects of the deposition on the adherence and friction properties of the surfaces were examined by modeling the geometrical condition. To this end, the height function distribution was used to exploit the surface friction model in conjunction with the DMT surface adhesion model. The results show the extent to which gold affects the adhesion and friction properties of the coated surfaces.     

Toward a general framework for jointly processor-workload empirical modeling

The Journal of Supercomputing - The complexity of state-of-the-art processor architectures and their consequent vast design spaces have made it difficult and time-consuming to explore the best...