Effect of HNTs addition in the injection moulded thermoplastic polyurethane matrix on the mechanical and thermal properties

The additions of nanofillers are able to enhance the mechanical properties of neat polymer matrix. There were few researchers reported on the mechanical properties of halloysite nanotubes reinforced thermoplastic polyurethane (HNTs-TPU) nanocomposites formed through casting and compression moulding. However, fewer researchers also reported study on HNTs-TPU formed through injection molding. The main objective of this paper was to study the effect of HNTs addition of TPU matrix on mechanical and physical properties. HNTs were mixed in TPU matrix using a brabender mixer with concentration ranging from 0.5 to 7 wt. % HNT loading (at specific mixing speed, mixing time and mixing temperature). Injection moulding was carried out to form tensile bar shaped specimens with specific moulding parameters (injection temperature, injection time and injection pressure). Increment around 35% of tensile strength of the specimen was found at 1 wt. % HNT loading concentration which exhibited the value of 24.3 MPa, compared to neat TPU; the best mixing. The Young’s modulus was increased with increasing HNTs loading. The elongation decreased with increasing HNTs loading. The FESEM results showed that HNTs were dispersed in TPU matrix. The TGA results showed that the addition of 1 wt. % HNTs enhanced the thermal properties. It can be concluded that HNTs-TPU has improved tensile and physical properties compared with neat TPU due to the addition of nanofiller

Antifungal and Antioxidant Activities of Pyrrolidone Thiosemicarbazone Complexes

Metal complexes of (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide (L) with Cu(II), Co(II), and Ni(II) chlorides were tested against selected types of fungi and were found to have significant antifungal activities. The free-radical-scavenging ability of the metal complexes was determined by their interaction with the stable free radical 2,2′′-diphenyl-1-picrylhydrazyl, and all the compounds showed encouraging antioxidant activities. DFT calculations of the Cu complex were performed using molecular structures with optimized geometries. Molecular orbital calculations provide a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms

Experimental and Numerical Investigations of Heat Transfer Characteristics for Impinging Swirl Flow

This paper reports experimental and computational fluid dynamics (CFD) modelling studies to investigate the effect of the swirl intensity on the heat transfer characteristics of conventional and swirl impingement air jets at a constant nozzle-to-plate distance (L = 2D). The experiments were performed using classical twisted tape inserts in a nozzle jet with three twist ratios (y = 2.93, 3.91, and 4.89) and Reynolds numbers that varied from 4000 to 16000. The results indicate that the radial uniformity of Nusselt number (Nu) of swirl impingement air jets (SIJ) depended on the values of the swirl intensity and the air Reynolds number. The results also revealed that the SIJ that was fitted with an insert of y = 4.89, which corresponds to the swirl number Sw = 0.671, provided much more uniform local heat transfer distribution on the surface. The CFD-predicted results help to explain the experimental measurements in terms of the turbulence intensity. Furthermore, the predicted and measured local Nusselt numbers were consistent with each other

Numerical Investigation of Heat Transfer and Friction Factor Characteristics in a Circular Tube Fitted with V-Cut Twisted Tape Inserts

Numerical investigation of the heat transfer and friction factor characteristics of a circular fitted with V-cut twisted tape (VCT) insert with twist ratio (y=2.93) and different cut depths (w=0.5, 1, and 1.5 cm) were studied for laminar flow using CFD package (FLUENT-6.3.26). The data obtained from plain tube were verified with the literature correlation to ensure the validation of simulation results. Classical twisted tape (CTT) with different twist ratios (y=2.93, 3.91, 4.89) were also studied for comparison. The results show that the enhancement of heat transfer rate induced by the classical and V-cut twisted tape inserts increases with the Reynolds number and decreases with twist ratio. The results also revealed that the V-cut twisted tape with twist ratio y=2.93 and cut depth w=0.5 cm offered higher heat transfer rate with significant increases in friction factor than other tapes. In addition the results of V-cut twist tape compared with experimental and simulated data of right-left helical tape inserts (RLT), it is found that the V-cut twist tape offered better thermal contact between the surface and the fluid which ultimately leads to a high heat transfer coefficient. Consequently, 107% of maximum heat transfer was obtained by using this configuration

Influence of Sulfuric Acid on the Tensile Properties of Halloysite Reinforced Polyurethane Composite / Tayser Sumer Gaaz...[et al.]

In this study, the mechanical properties of injection molded of HNTs-TPU composites were investigated. The composites were first made by adding halloysite nanotubes (HNTs) at weight percentages of 1, 2, and 3 wt.% to thermoplastic polyurethane (TPU). Then, HNTs were sulfuric acid-treated before adding to TPU at same weight percentage to create sulfuric acid HNTs-TPU composites. The samples were fabricated using injection molding. The HNTs-TPU composites were characterized according to the mechanical properties, including tensile strength, tensile strain and Young’s modulus. The highest mechanical values obtained at 2 wt.% HNTs loading, and similar findings are shown at the samples treated with sulfuric acid. The tensile strength increased until reach 23.78 MPa compare with the 17.7 MPa of the neat TPU, which showing about 25% improvement. For the acid-treated composites, the improvement has reached 34.4% compared to the neat sample. Regarding the tensile stain, the improvement was about 82% at 2 wt.% HNTs loading. The Young’s modulus results obtained in this study have shown that it is linearly improved with increment of loading content and sulfuric acid treated of HNTs. Where it achieving the highest values of Young’s modulus at 3 wt.% HNTs of 13.3 MPa and 15.2 MPa for untreated and treated, respectively

LiNbO 3

The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3 photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concrete surface under illumination of UV-visible or sunlight and showed that LiNbO3 achieved high conversion of CO2 into products despite the low levels of band-gap light available. The high reaction efficiency of LiNbO3 is explained by its strong remnant polarization (70 µC/cm2), allowing a longer lifetime of photoinduced carriers as well as an alternative reaction pathway. Due to the ease of usage and good photocatalytic efficiency, the research work done showed its potential application in pollution prevention

Heat Transfer Enhancement of Laminar Nanofluids Flow in a Circular Tube Fitted with Parabolic-Cut Twisted Tape Inserts

Numerical investigation has been carried out on heat transfer and friction factor characteristics of copper-water nanofluid flow in a constant heat-fluxed tube with the existence of new configuration of vortex generator using Computational Fluid Dynamics (CFD) simulation. Two types of swirl flow generator: Classical twisted tape (CTT) and Parabolic-cut twisted tape (PCT) with a different twist ratio (y = 2.93, 3.91 and 4.89) and different cut depth (w = 0.5, 1.0 and 1.5 cm) with 2% and 4% volume concentration of CuO nanofluid were used for simulation. The effect of different parameters such as flow Reynolds number, twist ratio, cut depth and nanofluid were considered. The results show that the enhancement of heat transfer rate and the friction factor induced by the Classical (CTT) and Parabolic-cut (PCT) inserts increases with twist ratio and cut depth decreases. The results also revealed that the heat transfer enhancement increases with an increase in the volume fraction of the CuO nanoparticle. Furthermore, the twisted tape with twist ratio (y = 2.93) and cut depth w = 0.5 cm offered 10% enhancement of the average Nusselt number with significant increases in friction factor than those of Classical twisted tape

Effect of Multipath Laser Shock Processing on Microhardness, Surface Roughness, and Wear Resistance of 2024-T3 Al Alloy

Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I>1 GW/cm2;  t<50 ns) at the interface between the metallic target and the surrounding medium (a transparent confining material, normally water) forcing a sudden vaporization of the metallic surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water) on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated

Synthesis of graphene/Cu2O thin film photoelectrode via facile hydrothermal method for photoelectrochemical measurement

The process of carbon dioxide (CO2) reduction by using efficient non-precious-metal catalyst to make the process be economical has brought a comprehensive research in the area. In this study, graphene layer in copper foil was easily synthesized using hydrothermal method at temperature 200°C in 3 h duration. Diffraction peaks in XRD at around 29°, 36°, 42° and 74° in the composites correlate to the (110), (111), (200) and (311) crystalline planes of cubic cuprous oxide (Cu2O), while peak at 27° showed the carbon graphitic peak. Raman confirms the presence of the graphene layer on Cu2O. Photoelectrochemical performance test of Graphene/Cu2O demonstrated that the photoelectrocatalyst showing the photocurrent density 9.6 mA cm-2 at -0.8V vs Ag/AgCl. This study demonstrated a potential of semiconductor-based hybrid electrode for an efficient photoelectrocatalytic of CO2 reduction

Novel Approach: Tungsten Oxide Nanoparticle as a Catalyst for Malonic Acid Ester Synthesis via Ozonolysis

Malonic acid ester was synthesized via the one-step ozonolysis of palm olein. Malonic acid ester was spectroscopically characterized using gas chromatography mass spectroscopy (GC-MS). Tungsten oxide nanoparticles were used as the catalyst, which was characterized via X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Tungsten oxide provided several advantages as a catalyst for the esterification malonic acid such as simple operation for a precise ozonation method, an excellent yield of approximately 10%, short reaction times of 2 h, and reusability due to its recyclability