5 research outputs found

    Synthesis of 1,3,5-Tris(phenylamino) Benzene Derivatives and Experimental and Theoretical Investigations of Their Antioxidation Mechanism

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    1,3,5-Tris­(phenylamino) benzene and a series of its substitution derivatives were synthesized. The structure of the as-synthesized products was confirmed by nuclear magnetic resonance spectroscopy and high resolution mass spectra. Moreover, the antioxidation behavior of 1,3,5-tris­(phenylamino) benzene and its substitution derivatives as antioxidants in several ester oils was evaluated by a rotary oxygen bomb test and pressurized differential scanning calorimetry, while theoretical calculations were conducted to examine their antioxidation mechanism. It was found that 1,3,5-tris­(phenylamino) benzene exhibits better antioxidation ability at elevated temperature (150 and 210 °C) than commonly used commercial antioxidant diphenylamine. In the meantime, the substitution groups exhibit significant effects on the antioxidation behavior of 1,3,5-tris­(phenylamino) benzene and its derivatives. This is because the substituents result in changes in the molecular structure and electronic effect of the as-synthesized products, thereby causing s change in their antioxidation behavior

    Enzymatic Oligomerization of <i>p</i>‑Methoxyphenol and Phenylamine Providing Poly(<i>p</i>‑methoxyphenol-phenylamine) with Improved Antioxidant Performance in Ester Oils

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    Poly­(<i>p</i>-methoxyphenol-phenylamine), denoted as P­(MOP-PA), was synthesized via the enzymatic oligomerization of <i>p</i>-methoxyphenol and phenylamine monomers in the presence of horseradish. The structure of the as-synthesized product was confirmed by Fourier transform infrared spectrometry, time-of-flight mass spectrometry, and elemental analysis, and the oligomerization process was studied by high-performance liquid chromatography. Moreover, the antioxidation behavior of P­(MOP-PA) as an antioxidant in several ester oils was evaluated by rotary oxygen bomb test and pressurized differential scanning calorimetry, and its antioxidant mechanism was discussed. It was found that, as the antioxidant in various base oils, P­(MOP-PA) exhibits excellent antioxidation ability at elevated temperatures of 150 and 210 °C. In addition, P­(MOP-PA) has an antioxidant ability that is better than that of poly­(<i>p</i>-methoxyphenol), and it exhibits an antioxidation ability in synthetic ester oil, such as di-iso-octyl sebacate, that is much better than that of several commonly used commercial hindered phenolic antioxidants

    Tribological Properties of Tungsten Disulfide Nanoparticles Surface-Capped by Oleylamine and Maleic Anhydride Dodecyl Ester as Additive in Diisooctylsebacate

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    Oleylamine (OM) and maleic anhydride dodecyl ester (MADE, synthesized at our laboratory) were adopted as the surface modifiers to prepare OM/MADE-capped tungsten disulfide (WS<sub>2</sub>) nanoparticles. An X-ray diffractometer and a transmission electron microscope were performed to analyze the microstructure and phase ingredients of the OM/MADE-capped WS<sub>2</sub> nanoparticles. Moreover, a four-ball friction and wear tester and a reciprocating tribometer were employed to evaluate the tribological properties of the surface-capped WS<sub>2</sub> nanoparticles as the lubricant additive in diisooctylsebacate (DIOS) from room temperature to 150 °C. The morphology of the worn steel surfaces and wear scars and their chemical states were investigated with a scanning electron microscope, three-dimensional profilometry, and an X-ray photoelectron spectroscope. Results show that OM-capped WS<sub>2</sub> nanoparticles nearly have no effect on the tribological properties of the DIOS base oil. The OM/MADE-capped WS<sub>2</sub> nanoparticles added in the same base stock at a concentration of 2.0% (mass fraction), however, exhibit good dispersibility and result in greatly improved tribological properties. The reason lies in that, after surface-capping by MADE containing polar group and OM containing coordination group, the OM/MADE-capped WS<sub>2</sub> particulates added in the base oil are well adsorbed on the sliding surfaces of the steel–steel contact to afford a chemisorption film with a low shear force. At the same time, OM/MADE-capped WS<sub>2</sub> nanoparticles as the additive in DIOS base oil take part in tribochemical reactions to form tribofilm composed of WO<sub>3</sub> and iron oxides on sliding surfaces, which also contributes to reducing the friction and wear of the steel sliding contact

    Ferromagnetism and Microwave Electromagnetism of Iron-Doped Titanium Nitride Nanocrystals

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    Titanium nitride (TiN) nanocrystals doped with different dosages of iron were prepared by calcinating nanotubular titanic acid precursor in flowing ammonia. The structure of as-prepared Fe-doped TiN nanocrystals was characterized, and their ferromagnetism and microwave electromagnetism were investigated. It has been found that as-prepared Fe-doped TiN nanocrystals exhibit distinct room temperature ferromagnetic properties and improved microwave electromagnetic loss behavior when compared with the undoped counterpart. Considering the crystal structure and chemical feature of as-synthesized products, we suppose that structural defects are responsible for the observed ferromagnetism and microwave electromagnetism of as-synthesized Fe-doped TiN, and it may be feasible to tune the magnetic and electromagnetic properties by manipulating the generation of the structural defects. Hopefully, the present research is to shed light on Fe-doped TiN nanocrystal as a promising microwave absorption material and to help acquiring insights into the origin of ferromagnetism and microwave electromagnetism in a broad range of nanostructures, thereby broadening the scope of dilute magnetic and electromagnetic wave absorbing materials

    Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films

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    A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, <i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (<5 layers) holey graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NH<sub>4</sub>NO<sub>3</sub> and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance)
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