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Graphene Enhanced Electrical Properties of Polyethylene Blends for High-Voltage Insulation
Zuojun Wei,Yaxin Hou,Chen Jiang,Haiyan Liu,Xiangrong Chen,Anyun Zhang,Yingxin Liu 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.5
Graphene as a novel additive in low density polyethylene (LDPE), high density polyethylene–low density polyethylene blend(10%HDPE–LDPE) and polypropylene–low density polyethylene blend (10%PP–LDPE), is investigated for promising ecofriendlyinsulating materials in high voltage cables. The composites with graphene amounts of 0, 0.002 wt%, 0.02 wt%,and 0.2 wt% are prepared by the solution mixing method. With attempt to disclose the structure–property relationships, thecomposites are extensively characterized by physical techniques including Fourier transform infrared spectroscopy, X-raydiffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetricanalysis and differential scanning calorimetry, and electrical measurements including electrical treeing, direct current conductivityand space charge distributions. Results show that graphene can significantly enhances the thermal stability of LDPEand 10%PP–LDPE, slightly decrease the degree of crystallinity, change the size of the crystal diameters, and improve thephase distribution of the polymer blends. Consequently, graphene can prolong the electrical tree initiation time and blockthe extension of electrical tree. Besides, it can modulate the trap distributions, which will further change the conductivityand ability to suppress space charge accumulations. This excellent performance of graphene could be attributed to its goodexfoliation, uniform dispersion and outstretched morphology in the polymer matrix, as well as its strong ability to captureelectrons.
Reactivity of Brönsted acid ionic liquids as dual solvent and catalyst for Fischer esterifications
Zuojun Wei,Feijin Li,Huabin Xing,Qilong Ren,Shuguang Deng 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Several water-stable ionic liquids with different acidity and affinity were synthesized and applied as both solvents and acid catalysts for Fischer esterification of ethanol reacting with four aliphatic carboxylic acids (acetic acid, n-hexanoic acid, lauric acid, and stearic acid). Among the studied ionic liquids, [(n-bu-SO3H) MIM][HSO4] (3-butyl- 1-(butyl-4-sulfonyl) imidazolium sulfate) and [(n-bu-SO3H) MIM][p-TSO] (3-butyl-1-(butyl-4-sulfonyl) imidazolium toluenesulfonate) show higher reactivity for the production of ethyl esters. The catalytic activities of these ionic liquids are strongly dependent on the acidity of their anions and cations, as well as their hydrophilicity and affinity with the reactants. Water refluxing through the condenser may be another important reason for obtaining high conversion of esterification, indicating a water-sequester process is still needed in order to obtain a higher yield of ester in the ionic liquid catalyzed esterification system. Kinetics studies show the conversions of the acids increase with reaction temperature and time, and reach equilibrium within about two hours. The apparent activation energies are 39.1±2.0, 49.7± 2.5, 51.4±2.5 and 59.3±3.0 kJ·mol−1 for the formation of ethyl acetate, ethyl n-hexanoate, ethyl laurate and ethyl stearate, respectively.
Zuojun Wei,Yuran Cheng,Mengting Chen,Yuhua Ye,Yingxin Liu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7
Using nitrogen-doped mesoporous carbon (NMC) as the support, several NiRe bimetallic catalysts withlow metal loading of 1 wt% were designed and prepared for the selective deoxygenation of oleic acid to n-heptadecanein the absence of hydrogen. Results showed that the Ni80Re20/NMC catalyst with a Ni/Re molar ratio of 80 : 20 achievedthe highest yield of n-heptadecane (92.3%) at 330 oC for 2 h in isopropanol solvent, and at a metal/oleic acid weightratio of 1 : 333. The catalyst can be reused at least five times with slight activity loss. Combined with the results of insituXRD, HRTEM, XPS and CO2-TPD, the formation of NiRe alloy, the very fine NiRe nanoparticle size at 2.30 nm, aswell as the hydrophobic, mesoporous and weakly basic properties of the NMC support surface were demonstrated tocontribute to the excellent catalytic performance of the catalyst.
Yingxin Liu,Zuojun Wei,Tiefeng Xing,Meng Lu,Xiaonian Li 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-
Gold catalysts supported on FeOx–TiO2 with various Fe2O3 contents were prepared by deposition– precipitation method and used for phthalic anhydride hydrogenation to phthalide. The effect of Fe2O3 on the physico-chemical property and the performance of Au/TiO2 were investigated. The reaction conditions were optimized. Adding 5 wt.% Fe2O3 on Au/TiO2 could enhance the activity and stability, which was contributed to the increase in the strength of the catalyst structure and the decrease in the loss of gold from catalyst. Using Au/5%FeOx–TiO2, phthalic anhydride conversion and phthalide selectivity reached 95.4% and 94.5%, respectively, at 190 8C and 3.0 MPa H2 for 7 h.