30 November 2019, Volume 50 Issue 11

    

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Focuses & Concerns(TheProjectofChongqingPressFundin2018)
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  Tuning on the photoelectric response and persistent photoconductivity of zinc oxide nanorod array films with Ag nanoparticles

  TONG Caihao, LU Linzhi, JIANG Xiaotong, XIE Changsheng

  Journal of Functional Materials. 2019, 50(11): 11001-11006. https://doi.org/10.3969/j.issn.10019731.2019.11.001

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  The surface modified Ag/ZnO nanorod array films (NRAs) were synthesized by a two-step method, and the time-resolved photocurrent curves excited by ultraviolet light at 365 nm were examined. Compared with pure ZnO NRAs, Ag/ZnO NRAs showed larger response values in the photoelectric response phase with a maximum value of 7 490, which was about 50 times the value of the pure ZnO NRAs. Moreover, the surface-modified Ag nanoparticles had a good regulation effect on the persistent photoconductivity (PPC) effect of ZnO NRAs. The photocurrent recovery efficiency of the pure ZnO NRAs was 25%, while the ZnO NRAs modified with Ag reached 87% in the same time. The higher the concentration of Ag, the less obvious the persistent photoconductivity (PPC) effect would be achieved. This phenomenon made it possible to adjust the PPC effect of the ZnO NRAs by simply changing the amount of Ag nanoparticles on the surface.
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  Research on induction heating welding process of large diameter Cu/Al alloy thin wall tube

  CAO Mengyun, CHENG Shiduo, HUANG Tian, LIU Xinkuan, MA Fengcang, LIU Ping, WANG Ziyan, XUE Siyu, CAO Kai

  Journal of Functional Materials. 2019, 50(11): 11007-11013. https://doi.org/10.3969/j.issn.10019731.2019.11.002

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  Using induction heating method, in this paper, a kind of operational and uncomplicated process was explored, by which large diameter thin-walled aluminum alloy and copper pipe could be welded. The effect of welding current, welding-length and welding high temperature insulation time on large diameter thin-walled copper aluminum tubes was studied. The microstructures of the interface were observed by scanning electron microscope (SEM) and polarizing microscope (PM), and the interfacial reaction products were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). When the heating time was 6 s and weld length was 15 mm, the quality of copper aluminum welded pipe was the best, and the tensile strength was highest. The copper-aluminum intermediate compounds layer were only Al₂Cu and AlCu, and no Al₄Cu₉-type compounds had been found.
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  Preparation of ethylcellulose-based conductive silver paste and properties of electronic paper

  HOU Chengmin, KOU Yanping, CAO Congjun

  Journal of Functional Materials. 2019, 50(11): 11014-11018. https://doi.org/10.3969/j.issn.10019731.2019.11.003

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  Low temperature curing conductive silver paste is a key functional material for the preparation of various electronic components. Silver and ethyl cellulose were used as conductive fillers. According to the mass ratio of ethyl cellulose/silver nitrate of 2∶1, 1∶1, 1∶2 and 1∶3, short rod-shaped conductive silver was prepared by redox method. Through the resistivity measurement and microscope observation, the effects of physical factors (heating sintering, ultraviolet light irradiation, water soaking, ultrasonic waves, etc.) on the electrical conductivity of the electronic paper formed by the short rod-shaped conductive silver paste were studied. The electronic paper obtained at a ratio of 2∶ 1 and 1∶1 was extremely resistant, and the electrical resistivity of the electronic paper at a ratio of 1∶2 and 1∶3 could be reduced to 50% to 60% of the initial value during the heating and sintering process. At the same time, the conductivity was relatively stable under the conditions of heating and sintering, ultraviolet light irradiation, water soaking, ultrasonic wave, etc., and the conductivity of ethyl cellulose/silver nitrate for the ratio of 1∶2 was extremely well. Finally, the conductive silver paste prepared by the ethyl cellulose/silver nitrate mass ratio of 1∶2 was mixed with the ink in a volume ratio of 30%, 45%, 60%, respectively. And the mixture was coated onto the paper to obtain electronic paper, and then sintered. The resistivity dropped to 96.6% of the starting value, which was 15 mΩ/cm.
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  Preparation and in vitro magnetic resonance imaging performance of modified cuttlefish melanin

  PENG Xiaoyang, CHEN Anqi, SUN Jinghua, ZHANG Ruiping

  Journal of Functional Materials. 2019, 50(11): 11019-11023. https://doi.org/10.3969/j.issn.10019731.2019.11.004

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  Melanin (MNP) was extracted from the ink sac of fresh cuttlefish, PEG functionalized and loaded with excess Mn²⁺ to prepare a water-soluble magnetic resonance imaging (MRI) contrast agent MNP-PEG-Mn nanoparticles. The morphology, particle size and zeta potential of MNP-PEG-Mn nanoparticles were characterized by transmission electron microscopy (TEM) and Malvern particle size analyzer, and further tested cytotoxicity by cell counting kit-8 (CCK8), and finally conducted in vitro relaxation performance test. The results showed that the MNP-PEG-Mn nanoparticles were spherical particles with good dispersity, the particle size was about 240 nm, and the zeta potential was -20.2 mV. The data of CCK8 assay showed that the survival rate of Hep2 cells after incubation with MNP-PEG-Mn for 24 h was more than 80 %, indicating that it had no obvious side effects and had good biosafety. In vitro MRI results showed that MNP-PEG-Mn image had obvious T₁ signal with the increase of Mn²⁺ concentration. Compared with the clinical contrast agent gadodiamide, the imaging effect of MNP-PEG-Mn nanoparticles in vitro was significantly enhanced, and its relaxation rate r₁ reached 37.09 mM^-1/s, which was much higher than gadodiamide 5.248 mM^-1/s.
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  Research on dielectric properties of CB/CNTs/PP conductive polymers under force/temperature

  CAI Honglei, YAN Xiaoxin, ZHANG Anjiang, SHAO Yu, ZHANG Minghua, DU Jianke

  Journal of Functional Materials. 2019, 50(11): 11024-11029. https://doi.org/10.3969/j.issn.10019731.2019.11.005

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  Conductive composites were prepared by melt blending and injection molding using polypropylene (PP) as a matrix and carbon black (CB) as fillers. The effects of electric field frequency, filler type, filler content, temperature and load on dielectric properties of the composites were determined. The results show that the dielectric constant and dielectric loss of the material increased with the increase of filler content at room temperature. With the increase of frequency (100 Hz-10 MHz), dielectric constant and dielectric loss of the composites decreased rapidly in the initial stage, and then tended to be stable. Dielectric constant of the composites increased significantly with the addition of CNTs, while when the filler content reached a certain value, the dielectric constant would decrease with the increase of CNTs. The change in space between carbon black particles caused by thermal expansion would decrease the dielectric constant of the composite with increasing temperature (30-100 ℃) at the same frequencies. The experimental results show that the material deformed with the compressive loading which would lead to the change of relative position between CB particles. As a result, the dielectric constant of the composites would decrease.
Review & Advance
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  Progress in the synthesis and application of fluorescent conjugated polymers

  YIN Weidong, MA Lamaocao, MA Hengchang

  Journal of Functional Materials. 2019, 50(11): 11030-11037. https://doi.org/10.3969/j.issn.10019731.2019.11.006

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  Organic conjugated polymers, which have attracted the much attention of researchers, have good application prospect in luminescent materials. Compared with fluorescent small molecules, fluorescent conjugated polymers have significant advantages of structural diversity, strong functionalization, good processability and simple synthesis. In recent years, fluorescent conjugated polymer materials have revealed important application value in the fields of chemical sensing, biological imaging, photoelectric device, adsorption and degradation of harmful substances. It summarized that fluorescence conjugated polymers could be synthesized by the Suzuki reaction, Sonogashira reaction, Wittig-Heck-McMurry reaction, and used in the fields of fluorescence regulation, chemical sensing, stimulation response, biological cell imaging, gas adsorption and degradation of organic dyes. The main research direction was to design and synthesize fluorescent conjugated polymers with specific recognition, higher sensitivity, easier processing, excellent stability and strong functionalization.
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  Recent progress of manganese dioxide/polyaniline (MnO₂/PANI) composite electrode materials

  ZHUANG Zhao, WANG Wenjiao, MA Yong, HAN Yongqin, BAI Ruiqin, LI Tingxi

  Journal of Functional Materials. 2019, 50(11): 11038-11044. https://doi.org/10.3969/j.issn.10019731.2019.11.007

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  Transition metal oxide manganese dioxide (MnO₂) and conducting polymer polyaniline (PANI) are two types of electrode materials, which are of great interest in supercapacitor applications. In this paper, these two kinds of supercapacitor materials and their energy storage mechanism were introduced. Furthermore, the applications and disadvantages of MnO₂ and PANI electrode materials and the research progress of MnO₂/PANI composites were introduced in detail. In the end, the problems of electrode materials in supercapacitors and the development trend of electrode materials in the future were summarized.
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  Progress in the catalytical synthesis of 2,5-furandicarboxylic acid

  WEI Yuejia, QI Fangya, LIAO Jia, MIN Yonggang, ZHAO Chen, LI Kaixin

  Journal of Functional Materials. 2019, 50(11): 11045-11056. https://doi.org/10.3969/j.issn.10019731.2019.11.008

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  2,5-furandicarboxylic acid (FDCA), as a derivative of furan, is an intermediate with good stability. It is a plastic monomer for the preparation of corrosion-resistant plastics with a rigid biomass base and is considered to be one of the most promising monomers for the production of sustainable polymer materials. In this article, the synthetic routes for the preparation of FDCA from metal catalysts and natural catalysts were reviewed, and the application prospects of FDCA was briefly described.
Research & Development
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  First principles study on the electronic properties of monolayer mxenes: Mo₂C, Zn₂N and Pb₂C

  WANG Yue, WANG Liying, CHEN Hongjian

  Journal of Functional Materials. 2019, 50(11): 11057-11064. https://doi.org/10.3969/j.issn.10019731.2019.11.009

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  In this paper, the crystal structures, band structures, densities of states and the effect of biaxial symmetric strains on the electronic properties of monolayer MXenes: Mo₂C, Zn₂N and Pb₂C were systematically investigated by using the first principles calculations. The calculated results show that Mo₂C was a stable half-metal with a large half-metallic band gap of 4.5 eV at the equivalent lattice parameter. And the total magnetic moment of Mo₂C was as large as 8.0 μB per formula unit. Meanwhile, Zn₂N showed a “semimetal” character at the equilibrium lattice parameter, while Pb₂C was an ordinary non-magnetic metal. Because the electronic properties and magnetic moment could usually be affected by the external strain for the two-dimensional materials, the strain effect of the electronic properties and magnetism on Mo₂C, Zn₂N and Pb₂C were also discussed.It is found that the half-metallicity of Mo₂C could be maintained in a wide biaxial symmetric strain range. For Zn₂N, it was quite insensitive to the tensile stres. However, the semi-metallic property of Zn₂N could be easily destroyed under the compressive biaxial symmetric strain. For Pb₂C, it could become into a semimetal at the compressive biaxial symmetric strain. As one of the few MXenes spintronics materials that have been developed, this series of materials, especially Mo₂C, would be a good candidate for low-dimensional spintronics materials in the future.
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  Preparation and thermal energy storage properties of palmitic acid /SiO₂ nanocapsules

  ZHANG Junqiang, WANG Huazhi, YANG Zhitao, ZONG Dongdong, MA Wenli

  Journal of Functional Materials. 2019, 50(11): 11065-11069. https://doi.org/10.3969/j.issn.10019731.2019.11.010

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  SiO₂ encapsulated composite was successfully synthesized by sol-gel process with tetraethyl orthosilicate as the precursor of SiO₂ in neutron condition for the first time. The results of XRD, FT-IR, SEM and TEM characterizations show that the prepared sample had spherical core-shell structure. The average size of the particles was about 474 nm. DSC and TGA results show that the latent heat of melting and solidifying was 109.9 J/g and 100.1 J/g, respectively. The encapsulation ratio and the encapsulation efficiency were 53.45% and 50.66%, respectively. The thermal energy storage properties and the thermal stability were both higher than those of the samples obtained at pH 3.5 and pH 11.5.
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  Effect of surface treatment agent on surface morphology and tensile properties of glass fiber

  HAO Mingyang, PAN Fusheng, ZENG Qingwen, TANG Aitao, LUO Chengyun, YAO Yuan

  Journal of Functional Materials. 2019, 50(11): 11070-11074. https://doi.org/10.3969/j.issn.10019731.2019.11.011

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  The two different surface treatment agents were respectively prepared by epoxy emulsion and polyurethane emulsion, and the two kinds of glass fibers, epoxy glass fiber (GF-EP) and polyurethane glass fiber (GF-PU), were respectively prepared. The surface morphology and mechanical properties of the glass fiber were characterized by scanning electron microscopy, atomic force microscopy and dynamic mechanical analysis. The results showed that the surface morphology of GF-EP showed granular and flaky protrusions, etc., and the surface roughness was 148.5 nm. The surface morphology of GP-PU was mainly smooth surface and sheet-like protrusion, and the surface roughness was 13.2 pm. Compared with GF-PU, the strength of monofilament GF-EP was increased by about 20.5%, and the elongation at break of the fiber was also increased by about 22.2%, but the modulus of both fibers was basically the same. Compared with the polyurethane emulsion, the particle size of the epoxy emulsion was only 1/4 of polyurethane emulsion particle size. Epoxy emulsion leaded to form a granular protrusion on the surface of the glass fiber, which significantly improved the surface roughness of the glass fiber. And at the same time, cracks formed during the rapid cooling of the glass fiber could be repaired, which made the fiber have certain toughness and improved the tensile strength of the glass fiber.
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  In-situ synthesis and visible-light-driven photocatalytic activity of Bi₂S₃@BiOBr

  LU Penghui, LUO Xiuzhen, TAN Mingyue, GAO Bifen

  Journal of Functional Materials. 2019, 50(11): 11075-11078. https://doi.org/10.3969/j.issn.10019731.2019.11.012

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  Bi₂S₃@BiOBr core-shell structure was obtained by a facile anion exchange process to form Bi₂S₃ in situ on the surface of BiOBr hollow microspheres, which were firstly prepared by a one-step solvothermal method. The crystal structure, morphology and photo-absorption property of the obtained samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis diffuse reflectance spectroscopy (DRS), etc. The photoelectrochemical property of the samples was also measured. The results showed that the intimate heterojunction between BiOBr and Bi₂S₃ greatly promoted the separation of charge carriers, resulting in the superior visible-light-driven photocatalytic activity for the degradation of methyl orange (MO). The sample containing 8% Bi₂S₃ exhibited the best photocatalytic performance. The radical trapping experiments demonstrated that ·O₂^- and h⁺ played decisive roles in the photo-degradation of MO.
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  Influence of PTFE additon on micro-structure and mechanical properties of Cr³⁺ composite coating

  ZHANG Genji, LI Wei, LIU Ping, ZHANG Ke, MA Fengcang, LIU Xinkuang, CHEN Xiaohong, HE Daihua

  Journal of Functional Materials. 2019, 50(11): 11079-11083. https://doi.org/10.3969/j.issn.10019731.2019.11.013

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  Different amounts of PTFE were doped in the process of Cr³⁺ electroplating to form Cr³⁺ composite coating. The effects of PTFE particles with different concentrations on the micro-structure and mechanical properties of Cr³⁺ composite coating were studied in this paper. The micro-structure and mechanical properties of Cr³⁺ coating were characterized and tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), nano-indenter and friction wear testing machine, respectively. The results show that different concentrations of PTFE had significant effects on the micro-structures and mechanical properties of Cr³⁺ composite coatings. When the concentration of PTFE in the plating solution was 12.5 mL/L, the current density was 35 A/dm², the pH was about 2.0, the temperature was 45 ℃, and the deposition time was 20 min, the obtained Cr³⁺ composite coating had the best comprehensive performance, with the hardness of 6.8 GPa and the lowest friction coefficient value of 0.28.
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  Preparation and properties of flame-retardant epoxy resins based on modified TiO₂ and DPPA

  LUO Qinqin, SUN Yulin

  Journal of Functional Materials. 2019, 50(11): 11084-11088. https://doi.org/10.3969/j.issn.10019731.2019.11.014

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  The hydrophilic nanometer titanium dioxide (TiO₂) was surface modified using (3-aminopropyl) triethoxy-silane. The structure of the modified TiO₂ was characterized by FTIR and TG. The flame-retardant epoxy resins were prepared based on the mixture of a fixed amount of 5,10-dihydro-phenophosphazine-10-oxide (DPPA) and different amounts of the modified TiO₂. And their flame-retardant,mechanical and thermal properties were studied. The results indicated that TiO₂ was successfully modified by APTS. The mixture of 2.5wt% DPPA and 0.05wt% modified TiO₂ gave epoxy resin UL-94 V-0 rating and a LOI value of 28.8%. The tensile and flexural strengths of the flame-retardant epoxy resin were 86.52, 116.75 MPa, respectively, both higher than those of epoxy resin without flame retardant. Moreover, its T_5% and T_g were as high as 364.3 and 162.0 ℃, respectively. The prepared flame-retardant epoxy resin possessed good comprehensive properties.
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  Microstructure evolution and magnetic properties of Fe₆₅Ni₃₅ nanocrystalline composite powders prepared by mechanical alloying

  YE Kunhuang, ZHANG Yunpeng

  Journal of Functional Materials. 2019, 50(11): 11089-11094. https://doi.org/10.3969/j.issn.10019731.2019.11.015

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  Fe₆₅Ni₃₅ nanocrystalline composite powders with excellent soft magnetic properties were successfully prepared by mechanical alloying using planetary high-energy ball mill, and soft magnetic composites were prepared by using powders with the best soft magnetic properties. The effect of grinding time on the microstructures and magnetic properties of Fe₆₅Ni₃₅ nanocrystalline composite powders was studied. The optimum grinding time was found to be 50 h. The preparation process, microstructure evolution and magnetic properties of Fe₆₅Ni₃₅ nanocrystalline composite powders coated with phenolic resin were further studied. The samples were characterized by XRD, SEM, vibration sample magnetometer and LCR. The results showed that the phase composition of Fe₆₅Ni₃₅ nanocrystalline composite powder changed from martensitic bcc structure to austenitic fcc structure with the increase of grinding time, and the reverse transformation was more obvious with the increase of grinding time. When the grinding time was 50 h, the average particle size of Fe₆₅Ni₃₅ nanocrystalline composite powder was stable at about 10 μm, showing the highest magnetization and the lowest coercivity, and the soft magnetic properties were optimal. The transformation of ferromagnetic martensite phase to weak magnetic austenite phase was the main reason for the difference of magnetic properties. Compared with pure Fe matrix composites, soft magnetic composites based on Fe₆₅Ni₃₅ nanocrystalline composite powder had higher resistivity, permeability and relaxation frequency and lower eddy current loss factor.
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  Synthesis and resonance peak tailoring of gold nanorods

  DAI Qionghua, LIN Lin, FENG Zhuohong, WANG Zhezhe, HUANG Lili, ZHENG Zhiqiang

  Journal of Functional Materials. 2019, 50(11): 11095-11099. https://doi.org/10.3969/j.issn.10019731.2019.11.016

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  Gold nanorods were synthesized by seed-mediated growth method. The effect of different pH values, hydrogen peroxide concentration and oxidation time on resonance peak position of gold nanorods was studied. The absorption peaks and morphology of gold nanorods with different oxidation time were characterized by UV-Vis absorption spectra and SEM, respectively. The result shows that gold nanorods shortened gradually with increasing oxidation time, while the diameter remained nearly unchanged. Moreover, the longitudinal surface plasmon resonance (SPR) peak of the gold nanorods showed a blue-shift gradually, while transverse SPR peak basically kept constant. The longitudinal SPR peak position changed approximately linearly as a function of the oxidation time.Within the margin of error, the longitudinal SPR peak wavelength of gold nanorods with different sizes was basically consistent with the calculated theoretical value.
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  Hydrothermal synthesis of hierarchical g-C₃N₄/SnO₂ heterostructures and their enhanced gas sensing properties

  ZHOU Qilin, ZHAO Bangyu, GUO Weiwei, HE Youzhou, LI Xiaodan, ZHOU Guilin, ZHANG Guizhi

  Journal of Functional Materials. 2019, 50(11): 11100-11108. https://doi.org/10.3969/j.issn.10019731.2019.11.017

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  Different proportions (0, 1%, 3%, 5%, 7%, 9wt%) of hierarchical g-C₃N₄/SnO₂ heterostructures were synthesized by one-step hydrothermal method. The crystal structure, morphology and optical properties of the materials were investigated by X-ray diffraction (XRD), infrared spectroscopy (FT-IR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), electron microscopy (SEM and TEM), BET specific surface area measurement and photoluminescence spectroscopy (PL). Meanwhile, the gas sensing performances of g-C₃N₄/SnO₂ nanostructures were investigated towards ethanol. The results showed that the gas response of 5wt% g-C₃N₄/SnO₂ based sensor was 77.5×10^-6 to 40×10^-6 ethanol at the optimum working temperature of 270 ℃, which was about 8.4 times higher than that of the pure SnO₂. Finally, the enhanced gas sensing mechanism of the g-C₃N₄/SnO₂ nanocomposite was discussed.
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  Electronic and optical properties of Nb doped SnO₂ studied by first-principles

  WANG Gui, WANG Likun, CAI Wenhao, YANG Jingkai, ZHAO Hongli

  Journal of Functional Materials. 2019, 50(11): 11109-11113. https://doi.org/10.3969/j.issn.10019731.2019.11.018

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  In this study, the electronic and optical properties of Nb doped SnO₂ were mainly investigated by using hybrid density functional (HSE06) with density functional theory. Results show that NTO had less structural distortion. The direct fundamental band gap of SnO₂ was 3.80 eV. However, the band gap of NTO was reduced but remained larger than 3.33 eV. The electron effective masses at the conduction band minimum (CBM) were first reduced and then increased effected by Nb 4d orbitals, and the lowering of the CBM relative to the vacuum level occurred after doping which increased the electron affinity (EA). In terms of optical properties, the widened optical band gap was obtained by Nb doping, and optical reflectivity in the infrared region was increased.
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  Durability test of carbon nanofiber reinforced concrete

  WANG Tengjiao, XU Jinyu, PENG Guang, MENG Boxu

  Journal of Functional Materials. 2019, 50(11): 11114-11121. https://doi.org/10.3969/j.issn.10019731.2019.11.019

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  To study the effect of carbon nanofibers on the durability of concrete, the freeze-thaw cycle test, penetration test and carbonization test of carbon nanofiber reinforced concrete with carbon nanofibers with different volume (0.1%, 0.2%, 0.3%, 0.4%, 0.5%) were carried out. In addition, the microscopic modification mechanism of carbon nanofibers to concrete durability was further investigated by SEM test. The results show that the carbon nanofibers could improve the micro-morphology of concrete through fiber bridging and pore filling, significantly improving the durability of concrete. When the content of carbon nanofibers was 0.3%, the frost resistance, impermeability and anti-carbonization performance of carbon nanofiber reinforced concrete were the best. When the number of freeze-thaw cycles was the same, as the amount of carbon nanofibers increased, the mass loss rate and compressive strength loss rate of concrete decreased first and then increased. The seepage height and relative permeability coefficient of concrete decreased first and then increased with the increase content of carbon nanofibers. Under the same carbonization age, the carbonation depth of concrete decreased first and then increased with the increase content of carbon nanofiber. Frost resistance, impermeability and anti-carbonization performance of carbon nanofiber reinforced concrete with 0.5% of carbon nanofibers were still better than that of plain concrete.
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  Study on influence factors of strength for hollow glass microspheres prepared by waste glass

  DUAN Ting, LI Yang, LIU Xiangfeng, CHANG Shibo, LI Yajie, LIU Kele, WANG Xiuhui, YANG Jinlong

  Journal of Functional Materials. 2019, 50(11): 11122-11127. https://doi.org/10.3969/j.issn.10019731.2019.11.020

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  As a new type of spherical glass functional material, hollow glass microspheres have broad application potential in many fields. In this paper, three kinds of hollow microspheres were obtained by spray drying-flame sintering method using waste flat glass as raw material and their corresponding strength were 5.34, 7.50 and 6.26 MPa, respectively.The physical and chemical properties, morphology, size and structure of the microspheres were analysed. It was found that the chemical compositions, particle size distribution and sintering temperatures of the microspheres had different effects on the strength of the microspheres.When sintering temperature was 900 ℃ and magnesium sulphate was added, the true density and the compressive strength of hollow glass microspheres were 0.94 g/cm³ and 8.03 MPa, respectively.
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  Hydrothermal synthesis of nanometer molybdenum disulfide and its electrocatalytic hydrogen evolution properties

  ZHANG Haoxing, HU Fangren, GUO Junhong

  Journal of Functional Materials. 2019, 50(11): 11128-11132. https://doi.org/10.3969/j.issn.10019731.2019.11.021

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  The two-dimensional molybdenum disulfide material has good electrocatalytic hydrogen evolution performance. However, different morphologies and crystals have a great influence on the electrocatalytic performance of molybdenum disulfide. In this paper, sodium thiosulfate or thiourea was used as the sulfur raw material, and the MoS₂ nanosheets were successfully synthesized by simple hydrothermal method. And then the synthesized MoS₂ nanosheets were calcined. X-ray diffraction (XRD), Raman spectroscopy (Raman spectrum) and scanning electron microscopy (SEM) were used to characterize the hydrothermally synthesized MoS₂ nanosheets and the calcined MoS₂ nanosheets. At the same time, the electrocatalytic hydrogen evolution performance of MoS₂ nanosheets and calcined MoS₂ nanosheets was tested. Experiments show that different sulfur sources and calcination treatment had certain effects on the morphology and hydrogen evolution performance of MoS₂ nanosheets. The MoS₂ nanosheets with sodium thiosulfate as the sulfur source exhibited a 2H structure and a 3R structure after calcination, which had a large initial overpotential and a large Tafel slope. The MoS₂ nanosheets with thiourea as the sulfur source were both 2H before and after calcination, and the hydrogen evolution performance of MoS₂ nanosheets with thiourea as the sulfur source was better than that of MoS₂ nanosheets with sodium thiosulfate as the sulfur source. The hydrogen evolution performance made it a promising hydrogen evolution reaction (HER) catalyst for practical applications.
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  SERS properties of paper-based GO/noble metal nanocomposites

  LIU Ruihua, WANG Zhezhe, LIN Lin, FENG Zhuohong, LI Jiabing, ZHENG Zhiqiang

  Journal of Functional Materials. 2019, 50(11): 11133-11137. https://doi.org/10.3969/j.issn.10019731.2019.11.022

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  Surface-enhanced Raman scattering is a highly sensitive and non-invasive analytical technique. This technique can be widely used for the identification and quantitative analysis of materials. In this paper, a simple method for preparing SERS substrates was proposed. First, graphene oxide (GO) was absorbed on the filter paper by leaching-lifting, followed by homogeneous deposition of noble metal nanoparticles by plasma sputtering on the filters. The surface-enhanced Raman scattering properties of the substrate were analyzed with a concentration of 10^-5mol/L rhodamine 6G (R6G). The results show that GO had a good fluorescence quenching effect in Raman detection. The gold and silver nanoparticleswith an absorption peak of 532 nm greatly enhanced the Raman scattering signal of R6G via localized surface plasmon resonance (LSPR). In addition, the fiber structure of the filters was able to capture more R6G molecules. Hence, the substrate exhibited excellent SERS characteristics.
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  Experimental investigation on the mechanical properties of Artemisia annua fiber reinforced concrete

  ZHANG Huzhi, HU Hao, ZHANG Danfeng, LONG Kun, HU Mingfei

  Journal of Functional Materials. 2019, 50(11): 11138-11143. https://doi.org/10.3969/j.issn.10019731.2019.11.023

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  Concrete is a typical building material with good compression resistance and weak tensile properties. It is a common idea to use fiber with outstanding tensile strength to reinforce the tensile defect of concrete. Among them, plant fibers with strong toughness, such as Artemisia annua fiber, is a material that is both economical and environmentally friendly. In this paper, the concrete cube test block was made by layering the Artemisia annua fiber uniformly in the concrete. On the one hand, the split test of some test pieces was carried out to explore the effect of the Artemisia annua fiber on the splitting tensile strength of concrete. On the other hand, the effect of Artemisia annual fiber on the compressive strength of concrete cubes was investigated by performing a standard cubic compressive test on some test blocks. The results show that the incorporation of Artemisia annual fiber could effectively improve the cubic compressive strength of concrete and significantly increase the splitting tensile strength of concrete. In addition, according to the theory of composite mechanics, mechanical analysis for artemisia annua fiber reinforced concrete was completed to derive the relationship between the tensile strength of Artemisia annua fiber reinforced concrete and artemisia annua fiber incorporation rate. Meanwhile, based on the test data, the empirical formulas for the splitting tensile strength and cubic compressive strength of the Artemisia annua fiber reinforced concrete were fitted with artemisia annua fiber incorporation rate as independent variable, and therefrom the optimum incorporation rate of artemisia annua fiber was obtained. Finally, the reasons for the influence of the incorporation of Artemisia annua fiber on the cubic compressive strength and splitting tensile strength of concrete cubes were discussed as well.
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  Synthesis of P(AA-SSS-DMAPS)/MMT composite and its application in Pb²⁺-adsorption behavior

  GONG Wei, LI Meilan, LIANG Tong, QU Nana, ZHANG Yuchen, LIU Bailing

  Journal of Functional Materials. 2019, 50(11): 11144-11150. https://doi.org/10.3969/j.issn.10019731.2019.11.024

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  The P(AA-SSS-DMAPS)/MMT composite with cross-linked structure was prepared by in-situ polymerization. And FT-IR, XRD, TG and SEM were employed to characterize their structure and properties, and the adsorption behavior of Pb²⁺ by P(AA-SSS-DMAPS)/MMT composites was studied. The results showed that the MMT was grafted onto the network of P(AA-SSS-DMAPS) and the composites with better heat stability was obtained. Moreover, due to the addition of MMT, it was found that P(AA-SSS-DMAPS)/MMT composite had larger specific surface area and adsorption sites. Under the conditions of an initial Pb²⁺ concentration of 0.01 mol/L, pH of 5.0, contact time of 150 min and an amount of P(AA-SSS-DMAPS)/MMT composite of 0.1 g, the adsorbent capacity of P(AA-SSS-DMAPS)/MMT composite for Pb²⁺ was found to be 247.8 mg/g and the adsorption system reached equilibrium. The adsorption of Pb²⁺ conformed Langmuir isothermal adsorption model. And thermodynamic studies showed that the adsorption of Pb²⁺ on the P(AA-SSS-DMAPS)/MMT composite was endothermic process, and due to ΔG<0, it indicated that the adsorption process could be carried out spontaneously.
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  Hydrogen production by LiAlH₄ and NH₄Cl in ether solvents

  WANG Xiaolian, CHEN Yungui, YANG Anchun, LIU Hucheng, CHENG Ming, WU Chaoling

  Journal of Functional Materials. 2019, 50(11): 11151-11154. https://doi.org/10.3969/j.issn.10019731.2019.11.025

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  The reaction of LiAlH₄ and NH₄Cl in ether solvent is a new type of controllable hydrogen technology with high hydrogen storage capacity and room temperature hydrogen release. The hydrogen evolution behavior of LiAlH₄ and NH₄Cl (LiAlH₄-NH₄Cl) with a molar ratio of 1∶1 in dimethyl carbitol (DC), dibutyl oxide (DO) and diethylene dioxide (DD) was studied. Studies have shown that LiAlH₄-NH₄Cl reacted in DC (LiAlH₄-NH₄Cl-DC) achieved good hydrogen evolution performance, and the hydrogen release capacities at 25, 40, and 60 ℃ could reach 4.01%, 4.53%, and 4.99wt%, respectively. The reaction of LiAlH₄-NH₄Cl in DD and DO (LiAlH₄-NH₄Cl-DD/DO) had a slower hydrogen release rate and a lower hydrogen release rate. The solubility of LiAlH₄ in the solvent was an important factor affecting the hydrogen evolution performance of the system.
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  Effect of calcium ammonium nitrate on the early age strength enhancing behavior of calcium sulfoaluminate cement paste at room temperature

  HUANG Rui, LIAO Yishun, XU Yuanyuan

  Journal of Functional Materials. 2019, 50(11): 11155-11160. https://doi.org/10.3969/j.issn.10019731.2019.11.026

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  The effects of calcium ammonium nitrate on the fluidity, setting time, compressive strength, electrical resistivity, internal temperature, heat of hydration, hydration products and pore structure of calcium sulfoaluminate cement pastes at room temperature and the mechanism of enhancing strength at early age were investigated. The results show that the initial fluidity of cement paste was obviously increased, the setting time was significantly shortened, and the compressive strength was significantly increased at 6 h, 1, 3, 7 and 28 d when the dosage of calcium ammonium nitrate increased from 0 to 5%. The occurring time of the peak was accelerated for the curve of rate of electrical resistivity versus time, and for the curve of internal temperature of cement paste, the internal temperature of cement paste was gradually increased, and the peak time of internal temperature was advanced. When the dosage of calcium ammonium nitrate was below 2%, the exothermic rate of cement hydration obviously accelerated, the accumulated heat at 1 d increased slightly, and the formation rate and content of ettringite increased. The dosage of 2% of calcium ammonium nitrate could significantly reduce the average pore radius, the total pore volume and porosity. Calcium ammonium nitrate could obviously enhance the hydration process and early-age strength of calcium sulfoaluminate cement, so it could be used as accelerating admixture.
Process & Technology
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  Effect of new polymer emulsion powder on the mechanical properties of carbon fiber reinforced concrete

  CHANG Sen, XU Jinyu, YANG Ning

  Journal of Functional Materials. 2019, 50(11): 11161-11165. https://doi.org/10.3969/j.issn.10019731.2019.11.027

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  In order to improve the mechanical properties of carbon fiber reinforced concrete, the effect of polymer latex powder content on the properties of concrete under the four carbon fiber content (0, 0.1%, 0.2%, 0.3%) was studied by adding VAE polymer latex powder. The compressive strength, flexural strength, compressive peak strain, flexural peak strain and compression ratio of concrete were analyzed. The test results show that with the increase of the amount of VAE polymer latex powder, the effect of latex powder on the performance of carbon fiber concrete increased first and then decreased. The performance of carbon fiber concrete was improved most obviously when the content of latex powder was within 4%-8%, and there was an interaction between carbon fiber content and latex powder content.
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  Preparation and properties of lauric acid/tetradecanol nanocomposite phase change materials

  WANG Sai, SUN Zhigao, LI Juan, LI Cuimin

  Journal of Functional Materials. 2019, 50(11): 11166-11171. https://doi.org/10.3969/j.issn.10019731.2019.11.028

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  LA-TD nanocomposite phase change materials (NPCMs) were prepared by adding Al₂O₃, Fe₂O₃ and CuO nanoparticles as additives and SDBS as dispersant, where lauric acid (LA) and tetradecanol (TD) were used as the substrate. The effect of nanoparticles of Al₂O₃, Fe₂O₃ and CuO, and the time of ultrasonic dispersion on NPCMs preparation wasstudied. The optimal preparation conditions of three NPCMs were determined. Under the optimal preparation conditions of NPCMs, the thermal conductivity, phase transition temperature and latent heat of the three NPCMs were measured by thermal conductivity tester and DSC. The solidification and melting experiments of NPCMs were conducted to study the effect of nanoparticles on the endothermic/exothermic rate of NPCMs. Fe₂O₃ nanoparticle was selected as the additive of NPCMs. The thermal conductivity of LA-TD NPCMs with 1wt% Fe₂O₃ was 0.3319 W/(m·K), which was 36.88% higher than that of LA-TD composite phase change materials. The phase transition temperature and the latent heat of NPCMs with Fe₂O₃ nanoparticle were 24.76 ℃ and 112.61 J/g,respectively. The endothermal rate wasimproved by adding Fe₂O₃ nanoparticle, the solidification time of NPCMs with Fe₂O₃ nanoparticle from 50 to 15 ℃ was shortened by 260 s(about 7.22%) compared to that of LA-TD composite phase change material. But the fluid viscosity of NPCMs increasedby adding nanoparticle, whichwentagainst natural convection heat transferduring the process of NPCMs melting. The NPCMs of LA-TD/Fe₂O₃ keptgood thermal stability after 300 cycles of melting and solidification.
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  Preparation and performance characterization of hydrophobic near-infrared low reflection and 8-14 μm low emissivity compatible coatings

  ZHANG Weigang, ZHANG Tao, LYU Dandan

  Journal of Functional Materials. 2019, 50(11): 11172-11177. https://doi.org/10.3969/j.issn.10019731.2019.11.029

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  Polydimethylsiloxane (PDMS)/Al-Sm₂O₃ composite coating with good hydrophobic property was prepared by scratch coating method using nano-SiO₂, PDMS, Al powders and Sm₂O₃ particles as micro-nano structural modifier, adhesives and functional pigments, respectively. The effects of the ratio of PDMS to pigments and the addition amount of nano-SiO₂ on the coating properties were discussed. The ratio of PDMS to pigments had an important effect on the coating properties. When the ratio of PDMS to pigments in the coating was 6∶4, the emissivity and the near-infrared reflectivity of 1.06 μm of the coating were 0.502 and 60.2%, respectively. The water contact angle could reach 124°, which was significantly higher than the conventional polyurethane-based near-infrared low reflection and 8-14 μm low emissivity compatible coating. Adding nano-SiO₂ to the coating formulation could significantly enhance the hydrophobic property of the PDMS/Al-Sm₂O₃ composite coating by increasing the roughness of the coating. When the amount of nano-SiO₂ was 8%, the water contact angle of the coating could be increased to 138°, the emissivity and the near-infrared reflectivity of 1.06 μm of the coating could still be as low as 0.524 and 55.2%.
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  Technological factors in TBA-aqueous based gel-casting

  LEI Yinyuan, LU Zhihua, ZHAI Qianqian, FENG Yajing, YU Ying, LI Yihan

  Journal of Functional Materials. 2019, 50(11): 11178-11181. https://doi.org/10.3969/j.issn.10019731.2019.11.030

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  Using acrylamide as monomer, gel-casting was enforced with a mixture of tert-butyl alcohol (TBA) and water as a solvent. The effects of TBA ratio, reaction temperature, the addition of the initiator and catalyst on the gelation time and colloidal form were investigated. The results showed that the gelation time increased with the increase of TBA ratio, but decreased significantly with the increase of reaction temperature. With the increase of the initiator content, gelation time significantly reduced to a certain level and remained stable, but increased linearly when the dosage of the initiator was continuously increased. The gelation time decreased with the increase of catalyst dosage, which changed significantly when the catalyst dosage was low. When the reaction temperature was 25 ℃, TBA ratio was 30 vol%, initiator was 2.5wt%, catalyst was 0.1wt% and the gelation time was 25 min, the surface quality of the sample was good and the drying shrinkage was low, which could meet the needs of engineering applications.
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  Effect of preparation method on the performance of CeO₂-ZrO₂-Al₂O₃ composite oxide after reductive treatment

  YANG Huanggen, YAN Quan, WEI Qingmin, CHEN Yuan, ZHU Ligang, QIN Liqin, XIAO Yihong

  Journal of Functional Materials. 2019, 50(11): 11182-11189. https://doi.org/10.3969/j.issn.10019731.2019.11.031

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  Ceria-zirconia-alumina composite oxides CZ+A(pm) and CZ+A(mm) (the molar ratio of Ce, Zr and Al was 1∶1∶2) were prepared by the mixing precursor of precipitates and the mixing precipitates mechanically methods, respectively. The samples were thermally aged in a flowing air atmosphere and in 10% H₂/Ar flow. The structure and performance of the composite oxides were studied by X-ray diffraction (XRD), N₂ adsorption-desorption (BET), oxygen storage capacity (OSC) measurements, and H₂ temperature-programmed reduction (H₂-TPR). The results show that the XRD patterns of CZ+A(pm)-H₂-1 100 exhibited many sharp diffraction peaks attributed to CeAlO₃, but CZ+A(mm)-H₂-1 100 reductively aged at 1 100 ℃ did not appear CeAlO₃ phase. The oxygen storage capacity (OSC) was 157 and 773 μmol/g, respectively, which were far higher than the 23.2 μmol/g of CZA-H₂-1 100, and the hydrogen consumption of H₂-TPR was 960 and 1 916 μmol/g, respectively, while the hydrogen consumption of CZA-H₂-1 100 was significantly reduced to 310 μmol/g. The OSC of CZ+A(pm) was affected by the formation of CeAlO₃ during the reductive treatment, which was consistent with the change result of reductive performance. It was found that CeO₂ and Al₂O₃ in CZ+A(pm) samples, with the particles of cerium-zirconium and alumina being small in scale and close in contact with each other, were more likely to produce CeAlO₃ through solid-phase combination reaction. However, the reductive treatment of CZ+A(mm) samples, for the cerium-zirconium and alumina particles being larger and farther apart, could inhibit the formation of CeAlO₃, thus significantly improving the oxygen storage performance and reductive performance of the material in the reduction atmosphere.
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  The effect of Ho³⁺ co-doping on up-conversion luminescence of NaYTiO₄∶Er³⁺ phosphor

  ZHANG Nan, FU Yao, ZHANG Changlong, SHI Yue, XING Mingming, TIAN Ying, LUO Xixian

  Journal of Functional Materials. 2019, 50(11): 11190-11193. https://doi.org/10.3969/j.issn.10019731.2019.11.032

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  The NaYTiO₄∶Er³⁺,Ho³⁺ up-conversion phosphors were successfully prepared by solid-state method at 1 100 ℃. The up-conversion luminescence (UCL) characteristics of the phosphor excited by 980 nm laser were systematically studied. The modulation effect of the doping ions on UCL color purity were also discussed. Spectrum measurement results confirmed that the emission peaks of the phosphor are located in 520-560 nm and 640-680 nm which correspond to the ²H_11/2,⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I₁₅ transfers of Er³⁺ ion, respectively. The Ho³⁺ ion doping has a significant effect on the spectral composition of the phosphor. The phosphor single doped with Er³⁺ ion mainly shows green emissions.When the phosphors are co-doped with Ho³⁺ ions, the red emission gradually dominates the UCL process and the intensity ratio value of red and green emissions (I_R/I_G) improves from 0.97 to 7.30 with the increasing Ho³⁺ concentration. Therefore, a red emission with excellent color purity is observed. This phenomenon can be attributed to the Er³⁺→Ho³⁺ energy transfer process.The energy transfer of ⁴S_3/2 (Er³⁺) +⁵I₈ (Ho³⁺)→ ⁴I_13/2 (Er³⁺) + ⁵I₆ (Ho³⁺) caused by Ho³⁺ co-doping provides an effective way for the green emission quenching of Er³⁺ ions.The following ⁴I_13/2→⁴F_9/2 excited state absorption process of Er³⁺ leads to significant enhancement on red UCL.
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  Preparation, encapsulation and characterization of paraffin/expanded perlite form-stable composite phase change materials

  MENG Duo, WANG Anqi, YANG Ji

  Journal of Functional Materials. 2019, 50(11): 11194-11198. https://doi.org/10.3969/j.issn.10019731.2019.11.033

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  To solve the problem of paraffin leakage during the phase change process of the paraffin-based composite phase change materials which was prepared by vacuum impregnation, the paraffin-based composite phase change materials was encapsulated by white latex. The chemical structure analysis of the encapsulated form-stable composite phase change materials was carried out by FT-IR. After encapsulated, the form-stable composite phase change materials was free of new substances and had a well chemical compatibility. The pore characteristics of expanded perlite and form-stable composite phase change materials and the adsorption of paraffin on the carrier matrix were characterized by SEM and mercury intrusion. The pore volume of expanded perlite after adsorption of paraffin was reduced by 91%. The DSC method was used to analyze the thermal properties of the phase change process of 25 and 32^# paraffin phase change materials after encapsulation. The phase change temperature remained basically unchanged, and the phase change enthalpy was 72.13 and 121.2 J/g. The TG curves were used to study the thermal properties of the paraffin-based composite phase change materials before and after encapsulation and the results showed that the thermal stability of the packaged composite phase change materials was improved by 11.95%.
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  Modification of graphene and friction and wear property of its epoxy resin matrix composites

  YU Sirong, SUN Weisong, TANG Menglong, WANG Xian, JI Zhikang, JIANG Qian, LIU Di

  Journal of Functional Materials. 2019, 50(11): 11199-11204. https://doi.org/10.3969/j.issn.10019731.2019.11.034

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  The graphene was modified by silane coupling agent KH560 and the epoxy resin was reinforced by the modified graphene(KH-graphene) to produce KH-graphene/epoxy resin composites. The effect of KH-graphene content and load on the friction and wear property of the composites was studied. The results showed that the KH560 was successfully grafted to the surface of graphene. The KH-graphene decreased the mass loss and friction coefficient of the epoxy resin. With increasing the KH-graphene content, the mass loss and friction coefficient of KH-graphene/epoxy resin composites both showed a decreasing trend, and when the load was 150 N, KH-graphene content was 0.5%, the mass loss and friction coefficient of composites were reduced by 44.9% and 17.4%. With increasing the load, the mass loss and friction coefficient of KH-graphene/epoxy resin composites also showed a decreasing trend. The wear form was mainly fatigue wear under the low load, and KH-graphene could inhibit the generation and expansion of micro-cracks. After the load increased, the wear form was mainly abrasive wear. After the graphene added, the wear scar of the composites’ wear surface was relatively reduced.
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  Preparation and properties of nano-silver particles/sulfonated polystyrene composite microspheres

  WANG Rong, ZENG Danlin, WANG Yuanyang, YANG Yuanyuan, QIN Ronghua, CHEN Bo, WANG Guanghui

  Journal of Functional Materials. 2019, 50(11): 11205-11210. https://doi.org/10.3969/j.issn.10019731.2019.11.035

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  In this paper, silver nanoparticles/sulfonated polystyrene (Ag/SPS) composite microspheres were synthesized by using sulfonated polystyrene microspheres (SPS) as carriers and loaded with silver nanoparticles on its surface. The composite microspheres were characterized by scanning electron microscopy, infrared spectroscopy, XRD spectroscopy and thermogravimetry. The results showed that at 70 ℃ and reaction time of 8 h, the monodispersity of Ag/SPS composite microspheres prepared by chemical reduction method was good and the silver nanoparticles were uniformly coated. The results of catalytic reduction of methylene blue showed that in a certain range, the higher the silver content of the composite microspheres, the faster the catalytic rate. The results of reuse experiments showed that the composite microspheres had high reusability.
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  Preparation and physical property analysis of porous oxalate titanate powder

  JIAO Mingchun, WANG Jing, MA Yudong, CHEN Hang, YUE Xianfang

  Journal of Functional Materials. 2019, 50(11): 11211-11214. https://doi.org/10.3969/j.issn.10019731.2019.11.036

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  Titanium oxalate is one of the key substances of the giant electrorheological effect material. In this paper, tetrabutyl titanate and oxalic acid were used as solute, and anhydrous ethanol was used as solvent to prepare porous titanyl oxalate powder by coprecipitation method. Physical properties such as particle composition, particle size, particle distribution, and conductivity were analyzed by XRD, SEM, laser particle size analyzer, etc. Then, the infiltration property of water and silicone oil on the surface was studied by the angle method. The results show that the average particle size of the powder was about 5 um, and the size was basically normal distribution. The particles were approximately spherical, and the surface was evenly covered with nano-scale pores. The contact angle of surface water on the surface of the material was between 26.8 and 31.1°, while the contact angle of the silicone oil on the surface of the sample was between 9.5 and 11.5°. Titanium oxalate had good wettability to both water and silicone oils. The wettability had little to do with the bath temperature and the pH of the solution. The contact angle of the surface of the titanyl oxalate prepared at conditions of 30,40,50,60 and 70 ℃, and pH=2 did not change greatly with the change of the bath temperature, but the wettability of the silicone oil on the surface of the sample was better than that of the water. Its resistivity was greater than 1 GΩ·cm measured by a four-probe method. It was an insulator.
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  Preparation of K_0.5Na_0.5NbO₃-based powders by surfactant-assisted solvothermal method

  ZHOU Yuan, LI Hui, CAI Yanzhi, WU Huaxia

  Journal of Functional Materials. 2019, 50(11): 11215-11220. https://doi.org/10.3969/j.issn.10019731.2019.11.037

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  The K_0.5N_0.5NbO₃-based powders was synthesized by surfactant-assisted solvothermal method. The influence of cosurfactant, surfactant and cosurfactant assistant surfactant on phase and morphology of K_0.5Na_0.5NbO₃ powders was studied. The results show that when adding different content of isopropanol (IPA), the K_0.5Na_0.5NbO₃ powders showed different structure and morphology. Surfactant made the morphology of powders regular, when isopropanol content was certain. With the increase of surfactant concentration (SBDS, PEG400), the morphology of powders made more regular and isopropanol could make the powder refine. Compared with SBDS, the PEG400 made the morphology of powders more regular. When the content of isopropanol (PEG400) was certain, the regular morphology powders with smaller particle size could be obtained by choosing appropriate isopropanol content. Namely, PEG400=1 g/L, V(IPA)/V(H₂O)=2/3 or 3/2 and the cubic particles with a particle size of about 300 nm could be obtained.