Exploitation of Nanobifiller in Polymer/Graphene Oxide–Carbon Nanotube,Polymer/Graphene Oxide–Nanodiamond,and Polymer/Graphene Oxide–Montmorillonite Composite: A Review

In this article, a comprehensive review is presented regarding structure, synthesis, and properties of nanofillers such as graphene oxide, nanobifiller of graphene oxide, and their polymeric nanocomposite. The information about hybrid properties and synthesis of graphene oxide–carbon nanotube, graphene oxide–montmorillonite, and graphene oxide–nanodiamond is presented. Use of nanobifiller in polymer/graphene oxide–carbon nanotube, polymer/graphene oxide–montmorillonite, and polymer/graphene oxide–nanodiamond composites was summarized. Area of polymer and graphene oxide-based nanobifiller composites is less studied in literature. Therefore, nanobifiller technology limitations and research challenges must be focused. Polymer/graphene oxide nanobifiller composites have a wide range of unexplored potential in technological areas such as automobile, aerospace, energy, and medical industries.     

New catalytic functions of Pd–Zn, Pd–Ga, Pd–In, Pt–Zn, Pt–Ga and Pt–In alloys in the conversions of methanol

Pd and Pt supported on ZnO, Ga₂O₃ and In₂O₃ exhibit high catalytic performance for the steam reforming of methanol, CH₃OH+H₂OCO₂+3HH₂, and the dehydrogenation of methanol to HCOOCH₃, 2CH₃OHHCOOCH₃+2HH₂. Combined results with temperature-programmed reduction (TPR) and XRD method revealed that Pd–Zn, Pd–Ga, Pd–In, Pt–Zn, Pt–Ga and Pt–In alloys were produced upon reduction. Over the catalysts having the alloy phase, the reactions proceeded selectively, whereas the catalysts having metallic phase exhibited poor selectivities.     

Effect of Carbon Nanotubes on the Structure,Internal Loss Storage,and Damping–Absorption Properties of CNT/PZT/RTV

Composites with damping–absorption performance and storage-loss behavior based on carbon nanotubes as a modifier and zinc titanate/room temperature vulcanized silicone rubbers as a matrix were fabricated by a reactive solution mixing process, wet ball milling, and the three-roller milling method. The microstructures, chemical structures, and morphologies of the composites were characterized by scanning electron microscopy, infrared spectroscopy, and X-ray diffraction. The thermal stabilities were investigated by thermogravimetric analysis. The effect of carbon nanotubes on the comprehensive performance of the carbon nanotube/zinc titanate/room temperature vulcanized silicon rubber composites was investigated. It was found that doping with carbon nanotubes can improve the comprehensive performance of the zinc titanate/room temperature vulcanized silicon rubber complex matrix. The best comprehensive properties were d₃₃?=?72 pC/N, storage modulus?=?4,100?MPa, loss modulus?=?400?MPa, damping coefficient?=?0.23, and absorption coefficients?=?0.4–0.6 for 4?wt% carbon nanotube/zinc titanate/room temperature vulcanized silicon rubber. In addition, the lattice parameters of zinc titanate were found to be highly dependent on the carbon nanotube content, and the absorption and damping performance of the composites were dependent on the frequency and temperature.     

Synthesis of dysprosium/Mn–Cu ferrite binary nanocomposite: Analysis of structural,morphological, dielectric,and optomagnetic properties

Manganese–copper ferrite (MCFO) and dysprosium (Dy)-doped manganese–copper ferrite nanocomposites (Mn_0.5Cu_0.5Dy_xFe_2−xO₄) (x = 0, 0.05, 0.10, and 0.15) were synthesized by sonochemical method. Crystal structure and the structural parameters of the MCFO were analyzed based on the doping concentration of Dy ion. It was observed that the average crystalline size of the synthesized nanocomposite decreases when the concentration of Dy increases. The existing spherical surface morphology of the MCFO and Dy-doped MCFO nanocomposites were obtained through scanning electron microscopy. In the UV spectrum, the pristine MCFO sample showed an absorbance peak at 743 nm whereas the absorbance values of Dy-doped ferrite nanocomposite considerably shifted (blue) toward a lower wavelength (231–222 nm). The dielectric parameters of all ferrite nanocomposites were studied in the frequency range of 100 Hz to 5 MHz. The dielectric spectrum revealed that dielectric constant and loss tangent decreased with increased doping concentration of Dy ion. The saturation magnetization also changed with Dy doping in MCFO. The impact of Dy on manganese–copper ferrite changed the optical, dielectric and magnetic properties of the prepared binary ferrite nanocomposite, which can be used for microwave-absorbing material applications.     

Preparation,characterization, and kinetic evaluation of dendrimer-derived bimetallic Pt–Ru/SiO2 catalysts

A series of silica-supported Pt, Ru, and Pt–Ru catalysts has been synthesized using dendrimer–metal nanocomposite (DMN) precursors prepared by both co- and sequential complexation with metal salts. The catalysts have been characterized by several techniques, including electron microscopy, temperature-programmed titration of adsorbed oxygen, and X-ray diffraction. Liquid-phase selective hydrogenation of 3,4-epoxy-1-butene (EpB) was used as a probe reaction to evaluate their catalytic performance. The bimetallic catalyst prepared by the co-complexation method exhibits a superior catalytic activity compared to the sequential one, and is much more active than a conventional catalyst prepared by incipient wetness. The activity enhancement is attributed to a bifunctional performance of the PtRu alloy sites created, based on a strong correlation between turnover frequencies, and both the alloy compositions and metal surface site distributions. In addition, the co-complexation catalyst is selective toward crotonaldehyde, suggesting that this reaction pathway is favored on the PtRu sites.     

Synthesis,densification and characterization of TaB2–SiC composites

The TaB₂–27.9 vol% SiC composite was synthesized by self-propagating high-temperature synthesis starting from mechanically activated Ta, B₄C and Si reactants. The obtained powders were spark plasma sintered at 1800 °C and 20 MPa for 30 min total time, thus obtaining a 96% dense product. The latter one was characterized in terms of microstructure, hardness, fracture toughness, and oxidation resistance. The obtained results, particularly the fracture toughness, are promising when compared to those related to analogous materials reported in the literature and fabricated with similar and different processing routes.     

Effect of zeolitic metal–organic framework on thermal,mechanical, and electrical properties of Ca/Zn-stabilized polyvinyl chloride

In order to enhance the heat stability of polyvinyl chloride (PVC), several heat stabilizing parameters such as metal content, antioxidant percentage, primary-to-secondary antioxidant ratios, stearic-to-acetylacetonate ratio, the amounts of pentaerythritol and β-diketone were studied using oven and Congo red tests. Results indicated that the percentage contribution of the calcium-to-zinc molar ratio in the static heat stability was 60.78%. Due to the synergistic effects of the calcium/zinc stabilizer and the zeolitic metal–organic framework (MOF) as an effective co-stabilizer, the heat stability was increased from 109 to 148 min. The EDX analysis was carried out to determine the mechanism of HCl gas absorption by the zeolitic imidazolate framework-8 (ZIF-8) existing in the PVC compound. Furthermore, the Ca/Zn thermal stabilizer showed poor electrical insulating properties, but the ZIF-8 improved electrical resistivity of the PVC compounds. Volume resistivity of ZIF-8 was significantly higher than that of the commonly used Ca/Zn stabilizers. Dynamic mechanical thermal analysis and tensile test of the PVC compound containing the ZIF-8 showed increased T_g and enhanced toughness.     

LC–ESI–QTOF–MS, MS/MS Analysis of Glycerophospholipid Species in Three Tunisian Pistacia lentiscus Fruit Populations

Three populations of Pistacia lentiscus fruits were analyzed for their contents, classes and different molecular species of glycerophospholipids (PL) in order to promote their production and marketability. The LC–ESI–TOF–MS and MS/MS were used to accomplish this analysis. Only four classes of PL were detected at different retention times—phosphatidic acid (PA), phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and phosphatidylinositol (PI). There was a significant difference in the relative observed abundance of various glycerophospholipid classes. PI was found to be the dominant class in the all provenances of lentisc fruit, followed by the PG class in the KO and RM populations. Within the TB population, the PA class is more abundant than PG and PE. The major molecular specie in the PA class is PA-C16:0/18:2 followed by PA-C18:1/18:2; and the minor species were determined to be PA-C16:0/18:3, and PA-C18:3/18:2. In the PE class of phospholipids PE-C18:1/18:1 and PE-C18:2/18:2 are the major species identified. The phospholipids PG-C18:2/18:2, PG-18:2/18:1, PI-C16:0/18:2 and PI-C16:0/18:1 are the most abundant species within the PG and PI classes. PG-C18:1/18:1, PI-C18:0/18:1 and PI-C16:0/18:3 are found to be only relatively minor chemical species. In conclusion, it is clear that the predominant molecular species of PL are those containing C16:0, C18;1, C18:2 fatty acids and the minor species are those containing C18:0 and C18:3.     

Optical properties of novel oxyfluoride glasses on the systems of LaF3–LaO3/2–NbO5/2 and LaF3–LaO3/2–NbO5/2–AlO3/2

Oxyfluoride glasses of xLaF₃–(60 − x)LaO_3/2–40NbO_5/2 (x = 0, 5, 10, 35) and xLaF₃–(60 − x)LaO_3/2–30NbO_5/2–10AlO_3/2 (x = 0, 10, 20, 30) were prepared using a levitation technique. Both the glass-transition temperature, T_g, and onset crystallization temperature, T_c, were lowered by substituting a part of the oxygen with fluorine in the glasses. An appropriate amount of fluorine maximized the difference between the temperatures, ΔT (= T_c − T_g), indicating the improvement in the glass-forming ability. The atomic packing densities of the glasses were approximately 60%, which gradually increased with the fluorine content. The absorption edge of the glasses shifted toward the shorter wavelength region in the ultraviolet spectra and toward the longer region in the infrared spectra by fluorine substitution. In addition, in one of the oxyfluoride glasses, a wide transparency from 307 nm to 9.2 µm was realized. Furthermore, the glass exhibited superior optical properties, with a combination of a high refractive index, n_d, of 2.020 and low wavelength dispersion, v_d, of 30.1. The effect of fluorine substitution on the n_d and its v_d was analyzed using the Lorentz–Lorenz dispersion formula.     

Effect of different nucleation catalysts on the crystallization of Li2O–ZnO–MgO–Al2O3–SiO2 glasses

Based on local raw materials, a range of LiZnMg aluminosilicate glasses were prepared to investigate the influence of TiO₂, Cr₂O_3, and ZrO₂ on the crystallization behaviour and thermal expansion characteristics. Differential thermal analysis showed that the crystallization propensity increases in the order TiO₂ > Cr₂O₃ > ZrO₂. Virgilite, β-spodumene ss, gahnite, enstatite and cristobalite were formed in the prepared glass-ceramics. The microstructure of glass-ceramic samples showed growths of rounded and subrounded grains in the base sample, whereas, somewhat rod-like and accumulated growths appeared in samples containing ZrO₂. However, a rather homogeneous texture of accumulated growths was developed in glass-ceramics containing TiO₂ and Cr₂O₃. The coefficient of thermal expansion of parent glasses was sensitive to the type of nucleating agent added (Cr₂O₃ > TiO₂ > ZrO₂) varying from 24.8 × 10⁻⁷ to 65.1 × 10⁻⁷ °C⁻¹ being almost unchanged with the heat-treatment. The microhardness values of glass-ceramic samples were in the 763–779 kg/mm² range.     

Synthesis,Characterization, and Antibacterial Activity of Polyindole/Ag–Cuo Nanocomposites by Reflux Condensation Method

Polyindole-based silver and copper oxide (polyindole/Ag–CuO) nanocomposites were synthesized using reflux condensation method by varying the concentrations of polyindole and silver nitrate with copper oxide in N₂ atmosphere. They were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The SEM images revealed fascinating shapes of CuO nanoparticles. The FTIR and XRD confirmed the functional group transformation and crystalline natures of silver and CuO existed in the nanocomposites. The polyindole/Ag–CuO nanocomposites were examined for antibacterial activity and found to exhibit the antibacterial activity against pathogenic bacteria.     

Microstructure,Thermophysical, and Ablative Performances of a 3D Needled C/C–SiC Composite

The microstructure, thermophysical, and ablative properties of a 3D needled C/C–SiC composite fabricated by chemical vapor infiltration combined with the liquid silicon infiltration process were investigated. The composite was composed of 64 wt% C, 20 wt% SiC, and 16 wt% Si. The thermal diffusivity in the plane direction was much higher than that in the through-the-thickness direction, while it was reversed for the coefficients of thermal expansion, and the differences reduced with increasing temperature. The linear and mass ablation rates in the oxyacetylene flame were 0.0039 mm/s and 0.0016 g/s on average, respectively. Various ablation processes including sublimation, thermochemical denudation, and oxidations occurred in different sections.     

The Content and Composition of Total,Free, and Esterified Sterols of Lotus Plumule Oil by GC–MS/FID

This study investigated the content and composition of total, free, and esterified sterols of three varieties of lotus plumule oil (Hunan lotus, Jiangxi lotus, and Fujian lotus) using GC–MS/FID. The fatty acid composition of sterol fatty acid esters (SFAE) was also analyzed and compared with that of triglycerides. Results showed that total sterol of lotus plumule oil (12.10–14.21 g/100 g) was higher than that of other plant oils (corn germ oil, 1.11 g/100 g; rapeseed oil, 0.78 g/100 g). No significant difference was found among the total sterol contents of the three types of lotus plumule oils (p > 0.05). Most sterol existed in ester forms (81.8–89.1%) rather than in free forms (8.4–10.1%). β‐Sitosterol (71.4–73.4%), and campesterol (6.2–7.5%) were the predominant fractions of free sterols. β‐Sitosterol (41.3–53.7%) and ?5‐avenasterol (27.1–31.1%) were the predominant fractions of esterified sterols, followed by campesterol (12.1–13.0%) and ?7‐avenasterol (3.4–3.7%). Linoleic acid (63.6–65.8%), oleic acid (8.3–10.4%), and behenic acid (9.0–9.9%) were the main fatty acids of SFAE, which were different from those of triglycerides. The results from this study suggest that lotus plumule oil may be a good resource of SFAE and can be used as a supplemental ingredient in functional foods.     

Investigation of the Electrode Properties of Glasses as a Method for Elucidating the Structural Role of Their Components: The 25Na2O–15TiO2–6ZrO2–4RxOy–50SiO2 System (R = Ca, Ba, Sr, La, Nb, and Ta)

Glass electrodes are fabricated from the title glasses, and the emf–pH curves are measured at room temperature. The structural role played by the glass components is elucidated from an analysis of the curves. The TiO₂, ZrO₂, Nb₂O₅, and Ta₂O₅ oxides are network-formers, and their effect on the electrode properties of glasses upon simultaneous introduction is summarized within the limits of the studied compositions, whereas the total acidity of the glass increases. The oxides of modifiers La, Ba, Sr, and Ca neutralize the acidic groups of the network-former (supposedly [ZrO_6/2]^2–). The tendency to neutralization decreases in the above order. The ionic electrode selectivity of glasses with an increased content of ZrO₂, which contain Nb₂O₅ and Ta₂O₅, is expressed by the series H⁺ Na⁺ > Li⁺ > K⁺.     

Structural,mechanical and tribological properties of Cu–ZrO2/GNPs hybrid nanocomposites

Hybrid Cu–ZrO₂/GNPs nanocomposites were successfully produced using powder metallurgy technique. The effect of GNPs mass fraction, 0, 0.5, 1 and 1.5%, on mechanical and tribological properties of the produced hybrid nanocomposite was studied while maintaining ZrO₂ mass fraction constant at 5%. High energy ball milling was applied for mixing powders and compaction and sintering were applied for consolidation. The morphological analysis of the produced powder showed acceleration of Cu particles fracture during ball milling with the addition of GNPs up to 0.5% with noticeable reduction of agglomeration size. Moreover, the crystallite size of Cu–5%ZrO₂/0.5%GNPs hybrid nanocomposites revealed smaller crystallite size, 142 nm, compared to 300 nm for Cu–5%ZrO₂ nanocomposite. Additionally, the hybrid nanocomposite with 0.5% GNPs shows homogeneous distribution of both reinforcement phases in the sintered samples. This improved nano and micro structure of Cu–5%ZrO₂/0.5%GNPs nanocomposites revealed higher hardness, 169.3 HV, compared to 65.5 HV for Cu–5%ZrO₂ nanocomposite. The wear rate is decreased in this composite while it increased with increasing GNPs content more than 0.5%. The coefficient of friction is decreased as well for this hybrid nanocomposite and remain constant with increasing GNPs content more than 0.5%.     

Synthesis,characterization and evaluation of Ni–Mo/Zr–Al2O3 catalyst for hydro-conversion of lignite-based heavy carbon resources

NaOH depolymerized products (SDP) of Shengli lignite was used as lignite-based heavy carbon resources in this study. Hydrotreatment of SDP over Ni–Mo/Al₂O₃ and Ni–Mo/Zr–Al₂O₃ catalysts was investigated. It was found that the incorporation of Zr to Ni–Mo/Al₂O₃ catalyst results in the easy reduction of metal oxides and the increase of the stacking degree and length of MoS₂ slabs. Both of Ni–Mo/Al₂O₃ and Ni–Mo/Zr–Al₂O₃ catalysts show better performance for hydrogenation of SDP and can be used repeatedly. The incorporation of Zr to Ni–Mo/Al₂O₃ catalyst significantly inhibits the formation of tetrahydrofuran insolubles (THFI), promotes the formation of two-ring aromatics and increases HS yield compared to that over Ni–Mo/Al₂O₃ catalyst.     

Synthesis,mechanical property,and thermal stability of reduced graphene oxide–zinc oxide/cyanate ester/bismaleimide resin composites

Reduced graphene oxide–zinc oxide/cyanate ester/bismaleimide resin (RGO–ZnO/CE/BMI) composites were synthesized via a blending method. The RGO–ZnO composite was incorporated into the CE/BMI copolymer to improve the properties of RGO–ZnO/CE/BMI composites. The structure, elements, and morphology of the RGO–ZnO composite were studied with XPS, FTIR, XRD, and SEM analyses. It indicated that the ZnO micro-sphere was attached to RGO by electrostatic attraction and the RGO–ZnO composite was prepared successfully. The mechanical properties and thermal stability of RGO–ZnO/CE/BMI composites were investigated. When RGO–ZnO composite was 1 wt.%, the flexural and impact strengths of RGO–ZnO/CE/BMI composites were 1.07 and 1.35 times of the CE/BMI copolymer, respectively. However, the RGO–ZnO composite tended to aggregate in the CE/BMI matrix with high loading. According to the SEM analysis, appropriate RGO–ZnO composite was evenly dispersed in the CE/BMI copolymer. Compared to the CE/BMI copolymer, the thermal stability of the RGO–ZnO/CE/BMI composites was good. Thus, the RGO–ZnO composite was successfully filled in the CE/BMI matrix; the mechanical properties and thermal stability of the RGO–ZnO/CE/BMI composites were enhanced.