A modus operandi toward interfacial enhancement of ethylene propylene diene monomer rubber/ polybenzoxazine blends using EPDM-grafted-vinyltrimethoxysilane copolymer

Compatibilization of polymer blends is performed to obtain synergistic effects in physical and mechanical properties. The present work demonstrates the ability of vinyltrimethoxysilane-grafted-ethylene propylene diene monomer rubber (VTMS-g-EPDM) to improve the compatibility between EPDM and polybenzoxazine (PB). EPDM reacted with 5 phr of VTMS showed the highest grafting efficiency as well as a relatively low gel content, and was added to EPDM/PB blends. The addition of 8 phr of compatibilizer to 70/30 (w/w) EPDM/PB reduced the dispersed PB droplet size from 3.1 μm to 800 nm. Effects of various blend compositions at constant dosage of compatibilizer (8 phr) on the swelling behavior and tensile properties of the samples were also studied. The tensile strength increased from 12 to 14.5 MPa upon adding the compatibilizer at 50/50 blend ratio of EPDM/PB; however, the increase in the PB content had no significant impact on the tensile strength in both compatibilized and non-compatibilized samples.     

Fabrication of polymeric solar thermal fuel composite for solar energy storage applications

Solar energy storage and conversion have remained significant global challenges. This article discusses how to fabricate a polymeric solar thermal fuel (P-STF) composite with unique thermal storage abilities. In this regard, we aim at developing a novel method for dispersing multi-walled carbon nanotubes (MWCNTs) functionalized with azobenzene molecules (modified azobenzene molecules) in ethylene-vinyl acetate (EVA). The modification of azobenzene (functionalization) enhances the energy storage density of AZO molecules, and the addition of fillers (MWCNT) leads to the production of the P-STF composite with the potential to store and convert solar energy to thermal energy. The differential scanning calorimetry (DSC) test verifies the P-STF composite's capacity to absorb solar energy and release it as heat. Thus, the uncharged nanocomposites required heat energy at the melting point temperature of EVA (Enthalpy 18.392 J/g). However, the EVA-AZO-MWCNT 10% and EVA-AZO-MWCNT 5% nanocomposites released heat energy rather than requiring it to melt with enthalpy −37.6526 and −1.2609 J/g, respectively, which indicates the heat release in the P-STF composite. Moreover, oscillatory shear rheological measurement (RMS) and field emission scanning electron microscopy (FESEM) demonstrate that modified azobenzene (MWCNT-AZO) is well dispersed in the polymer matrix (EVA).     

Graphene oxide coated wad as a new sorbent in fixed bed column for the removal of crystal violet from contaminated water

An efficient method was developed to fabricate graphene oxide coated cotton wad (GO/W) using self-assembly technique. GO/W could be used as an adsorbent material in remediation of environmental pollutants in a continuous packed bed column. The efficiency of GO/W fixed bed column in the removal of crystal violet (CV) from an aquatic environment was studied. The experimental breakthrough data were modeled using Thomas, Adams-Bohart, and Yoon-Nelson models, and the column parameters for all these models were calculated. Increasing the effluent discharge rate and initial adsorbate concentration make the breakthrough and saturation points to be obtained faster and hence lower the adsorption capacity of column.     

Effect of Organoclay Ordering and Agglomeration on Morphology and Mechanical Properties of Uncured and Dynamically Cured Ethylene‐Octene Copolymer Nanocomposites

In this work, the effects of organoclay (OMMT) and cross‐linking agent on thermal and mechanical properties as well as the morphology of dynamically cured nanocomposites based on ethylene‐octene copolymer are studied. The nanocomposites containing 1, 3, 5, and 7 wt% OMMT are first prepared and then cured with 0.5 and 1 wt% dicumyl peroxide. Low angle X‐ray scattering and transmission electron microscopy reveal that the size of clay tactoids is increased with the increase of OMMT content within the nanocomposites especially for the uncross‐linked matrix. In addition, the distance between adjacent clay layers is increased for the cured nanocomposites containing 1 and 3 wt% OMMT, however, it remains relatively unchanged for higher amounts of the nanofiller. In uncross‐linked systems, the nanocomposites containing up to 5 wt% OMMT exhibit a remarkable enhancement in stress and strain at break compared to that of the matrix alone. With the addition of further OMMT content, although the stress and strain at break are both decreased, still remained much higher than that of the pristine copolymer. A mechanism is also proposed to compare the microstructure of the uncured and cured nanocomposites before and after stretching.

     

Synthesis and Characterization of Ferromagnetic BaFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanocrystals Using Novel Ionic Precursor Complex [Fe(opd)<Subscript>3</Subscript>]<Subscript>2</Subscript>[Ba(CN)<Subscript>8</Subscript>]

The following investigation reports the synthesis of novel complex [Fe(opd)₃]₂[Ba(CN)₈] and preparation of BaFe₂O₄ nanoparticles through thermal decomposition without using any surfactant. The complex was characterized via Furrier transform infrared spectroscopy (FT-IR), ultra violet-visible spectroscopy (UV–vis), conductivity measurement and elemental analysis. The synthesized crystals of inorganic precursor complex was transferred to furnace, where they were calcined under normal atmosphere condition at 900 °C for 4 h. Formation of BaFe₂O₄ was supported by FT-IR and energy-dispersive X-ray analysis. Hexagonal structure of nano-oxide was confirmed on powder X-ray diffraction. Furthermore, uniform morphology of nanocrystals were reported by scanning electron microscopy. The saturation magnetization (22 emu/g), remanent magnetization (6 emu/g) and coercivity (400 Oe) reported on vibrating sample magnetometer curve illustrates the promising industrial and medicinal applications of prepared mixed oxide.     

Fatigue of sintered steels (Fe-1.5 Mo-3 Mn-0.7 C)

The powder metallurgy process is ideally suited to the mass production of structural parts of complicated shape and with tight tolerances without appreciable loss of material. Because of its unique attributes such as reducing weight and production cost, powder metallurgy has made very significant in roads as a substitution technology in automotive parts, such as cams and gears in this process, we can improve the mechanical properties such as fatigue resistance of PM materials by changing of manufacturing parameters, for example, density, sintering temperature, sintering time, etc. In this research, the fatigue behaviour of sintered steel (Fe-1.5 Mo-3 Mn-0.7 C) was investigated with varying of density and sintering temperature. The results showed that in this steel, increase of porosity plays an important role in the fatigue limit of specimens also with sintering at high temperature which results in more spherical pores, the fatigue strength was improved. In this research, SEM fractography was also used to determine the mechanism of fatigue fracture.     

α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> based nanomaterials as gas sensors

Interest in detecting and determining concentrations of toxic and flammable gases has constantly been on the increase in recent years due to increase of modernization, industrialization and high standards of life. Detection of such gases is very important in many different fields such as industrial emission control, household and social security, vehicle emission control and environmental monitoring. Metal oxide gas sensors are among most important devices to detect a large variety of gases. α-Fe₂O₃, an environmental friendly semiconductor (E _g = 2.1 eV), is the most stable iron oxide under ambient atmosphere and because of its low cost, high stability, high resistance to corrosion, and its environmentally friendly properties is one of the most important metal oxides for gas sensing applications. This is the first review about gas sensing properties of α-Fe₂O₃ nanostructures. In this paper gas sensing properties of α-Fe₂O₃ are extensively reviewed. After a brief explanation about metal oxide gas sensors and α-Fe₂O₃, sensors based on α-Fe₂O₃ nanomaterials have been reviewed. Gas sensing section is divided into five subsections: pure α-Fe₂O₃ gas sensors, metal/α-Fe₂O₃ gas sensors, metal oxide/α-Fe₂O₃ gas sensors, polymer/α-Fe₂O₃ gas sensors and graphene/α-Fe₂O₃ gas sensors.     

Development of 3D printing technology for the manufacture of flexible electric double-layer capacitors

This study presents a novel process and manufacturing system for the fabrication of Electric Double-Layer Capacitors (EDLCs) as energy storage devices. It shows an approach for printing multilayer EDLC components using 3D printing technology. This process allows layers of activated carbon (AC) slurry, gel electrolyte, and composite solid filaments to be printed with high precision. The study describes the detailed process of deposition of the AC and gel electrolyte using the dual nozzle system. The performance of the flexible EDLCs manufactured by 3D printing in a rectilinear infill pattern has been investigated. It describes the energy storage performance of the printed supercapacitors in relation to the differences in thickness of the AC printed layers and the differences in density of gel electrolyte. A supercapacitor based on printed AC and composite materials displays a specific capacitance of 38.5?mF?g^?1 when measured at a potential rate change of 20?mV?s^?1 and a current density of 0.136?A?g^?1. The highest energy density value for the flexible EDLC was 0.019?Wh?kg^?1 and power density of 165.0?W?kg^?1 in 1.6?M H₂SO₄/PVA gel electrolyte.     

A Combined Analytic,Numeric, and Experimental Investigation Performed on NiTi/NiTiCu Bi‐Layer Composites under Tensile Loading

Adjusting mechanical behavior and controlling deformation parameters are significant tasks in designing shape memory components. In this paper, an analytical model describes the deformation behavior of NiTi/NiTiCu bi‐layer composites under tensile loading. Different deformation stages are considered based on single mechanical behavior at each stage. Closed‐form equations are derived for stress–strain variations of bi‐layer composites under uniaxial loading–unloading. Bi‐layer composites made via the diffusion bonding method from single layers of NiTi alloy with a composition of Ti‐50.7 at.% Ni, as an austenitic layer, and Ti‐45 at% Ni‐5 at% Cu, as a martensitic layer, are produced by the vacuum arc remelting technique. The tensile behavior of single‐ and bi‐layers is investigated by using loading–unloading experiments to find the nominal stress–strain curves. Numerical simulations are also done by employing Lagoudas constitutive model to simulate stress–strain diagrams. The solutions of the analytical method presented are validated by using the numerical simulations as well as the experimental results. With regard to the results obtained from the analytical modeling, the numerical simulations, and the experiments, it is evident that the bi‐layer composites with different thickness ratios provide adjustable mechanical behavior that can be considered in different application designs, for example, actuators equipped with shape memory components.

     

Synthesis and characterization of $$\hbox {BaNiO}_{3}$$ using a solid-state thermal decomposition method and the preparation of its stable aqueous suspension

In the present study, the preparation of \(\hbox {BaNiO}_{3}\) nano-oxide is reported via simple solid-state thermal decomposition of \([\hbox {Ba(en)}_{4}][\hbox {Ni(H}_{2}\hbox {O})_{2}\hbox {(NCS)}_{4}]\) precursor complex for the first time. As-prepared nano-oxide was coated by citric acid to form a stable aqueous magnetic suspension. The precursor complex was characterized by conductivity measurements, ultra violet–visible spectroscopy, elemental analysis and Fourier transform infrared spectroscopy. The composition of the perovskite was confirmed by energy-dispersive X-ray spectroscopy analysis and the hexagonal structure was supported by powder X-ray diffraction. In addition, monotonous morphology of the nano-oxide was illustrated by field-emission scanning electron microscopy. Superparamagneticity of the nanoparticles were detected using a vibrating sample magnetometer. Finally, the hydrodynamic size as well as the zeta potential of the pristine and surface-treated \(\hbox {BaNiO}_{3}\) nano-oxide were measured in deionized water via a dynamic light scattering analyzer and they were compared. Results show the excellent stability of the surface-modified magnetic oxide compared to the pristine.