Co-reporter:Z.J. Yu, M. Rajesh Kumar, D.L. Sun, L.T. Wang, R.Y. Hong
Materials Letters 2016 Volume 166() pp:284-287
Publication Date(Web):1 March 2016
DOI:10.1016/j.matlet.2015.12.102
•Hexagonal shaped ZnO nanoparticles were prepared by using co-precipitation method.•PVP capped ZnO nanoparticles were better than uncapped ZnO.•An enhanced PL emission was observed in PVP capped ZnO nanoparticles.ZnO nanoparticles were successfully prepared by co-precipitation method. Polyvinylpyrrolidone (PVP) was proposed to graft onto the nanosized ZnO as a surfactant to reduce the particle size and also decreases the aggregation. The synthesized nanoparticles was characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible absorption (UV–vis), Photoluminescence (PL) and Thermogravimetry (TG) study. The results showed that the crystalline quality, functional groups and the optical property of ZnO nanoparticles were improved. From SEM images, the dispersion and particle size improved a lot.
Co-reporter:D.L. Sun, F. Wang, R.Y. Hong, C.R. Xie
Diamond and Related Materials 2016 Volume 61() pp:21-31
Publication Date(Web):January 2016
DOI:10.1016/j.diamond.2015.11.004
•Plasma pyrolysis was reinforced by electrical heating pyrolysis.•Carbon source was activated by plasma and then thermally decomposed in heating area.•Optimal operation parameters and CB generation mechanism were determined.•Nucleation under plasma with/without thermal pyrolysis was studied.Carbon black (CB) was prepared via arc discharge non-thermal plasma which was enhanced by thermal pyrolysis process, in which propane was cracked into CB with controlled structure and hydrogen. Argon was also introduced along with the propane. Detailed parameters like discharge current, argon flow rate, propane flow rate and cracking temperature were discussed in order to obtain optimal conditions for generating CB with high productivity, yield and well developed structure. The morphology of CB was characterized by scanning and transmission electron microscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and BET surface area analysis were used to analyze the structure of CB. The results showed that the yield of CB could be 85.9% under optimal operating conditions; the spherical CB produced by this process possessed a narrow size distribution. Thermal pyrolysis began to significantly serve above 500 °C, and the yield under 700 °C was higher than that of plasma process without electrical heating assistance. Resistivity of the CB was decreased with increasing discharge current and pyrolysis temperature. Mechanism of CB formation in our process was assumed according to experimental phenomenon and the widely accepted formation mechanism of furnace-type CB.
Co-reporter:J.J. Yuan;R.Y. Hong;Y.Q. Wang;W.G. Feng
Polymer Composites 2016 Volume 37( Issue 4) pp:1078-1084
Publication Date(Web):
DOI:10.1002/pc.23269
A conductive coatings was prepared using a kind of spherical carbon black (CB) as conductive pigment and polyacrylate (PA) as polymer matrix. The conductive pigment CB nanoparticles were prepared by AC plasma arc method, and then treated with concentrated nitric acid. The pristine and oxidized CB nanoparticles were characterized by scanning and transmission electron microscopy. Afterwards, CB powders were dispersed in PA to produce conductive coatings. The effects of CB content and titanium coupling agent on the volume resistivity were investigated. Furthermore, the rheological and mechanical properties of PA/CB coatings were also investigated. The results showed that the volume resistivity of the PA/CB films was decreased with the increasing of CB content and the electrical percolation threshold was about 2.0 wt%. An interesting result could be observed that the rheological threshold value was close to electrical percolation threshold. In addition, the tensile properties were improved with the addition of CB nanoparticles. POLYM. COMPOS. 37:1078–1084, 2016. © 2014 Society of Plastics Engineers
Co-reporter:Q. Chen, R.Y. Hong
Ceramics International 2015 Volume 41(Issue 2) pp:2533-2542
Publication Date(Web):March 2015
DOI:10.1016/j.ceramint.2014.10.128
Ba0.5Sr0.5TiO3 particles with perovskite phase were successfully synthesized by molten salt assisted co-precipitation using inexpensive TiOSO4 as raw material. The effect of the amount of molten salt on the formation, morphology, and dielectric properties of Ba0.5Sr0.5TiO3 particles was investigated. Ba0.5Sr0.5TiO3-polyaniline (PANI) hybrid particles were then synthesized by in situ polymerization of aniline with Ba0.5Sr0.5TiO3. The obtained Ba0.5Sr0.5TiO3-PANI hybrid particles were characterized through thermogravimetry (TG), X-ray diffraction (XRD), Fourier-transform-Infrared (FT-IR) and scanning electron microscopy (SEM). The three-phase composites by incorporating Ba0.5Sr0.5TiO3-PANI hybrid particles in Polystyrene (PS) matrix were demonstrated. SEM showed that the Ba0.5Sr0.5TiO3-PANI hybrid particles were distributed in the continuous PS matrix heterogeneously without obvious aggregation. Moreover, the glass transition temperature and thermal stability of composites were improved with the addition of hybrid particles. The three-phase composites were attractive candidate as embedded capacitors.
Co-reporter:B.B. Zhang, Y. Chen, F. Wang, R.Y. Hong
Applied Surface Science 2015 Volume 351() pp:280-288
Publication Date(Web):1 October 2015
DOI:10.1016/j.apsusc.2015.05.106
Highlights
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CB was modified through the method of oxygen plasma treatment.
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Surface modified CB applied in PC/ABS blends.
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The treated CB showed better compatibility in PC/ABS blends.
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PC/ABS blends with treated CB showed better mechanical and thermal properties.
Co-reporter:Zhenliang Feng, Wenrui Wei, Litong Wang and Ruoyu Hong
RSC Advances 2015 vol. 5(Issue 117) pp:96911-96917
Publication Date(Web):30 Oct 2015
DOI:10.1039/C5RA19642F
Cross-linked PS-DVB/Fe3O4 microspheres (PFM-3) have been successfully synthesized by a new magnetic colloid swelling polymerization method and further functioned by alternatively using methylamine and 1,4-butanediol diglycidyl as monomers to build a branching polymer with quaternary ammonium groups. The characterization of PFM has been performed by XRD, FT-IR, SEM, TEM and BET surface area analyses. The results showed that PFM-3 possessed a high ion adsorption capacity (149.25 mg g−1) and could adsorb nitrate ions from water efficiently. The material also showed excellent reusability (after washing with sodium chloride, the absorption capacity was little reduced). More importantly, the magnetic microspheres could be removed from waste water easily via introducing an external magnetic field, which made the discoveries in this study provide an effective and environmentally friendly approach for fast removal of nitrate from waste water.
Co-reporter:Xianjun Wang;Ping Zhang;Ruoyu Hong
Journal of Applied Polymer Science 2015 Volume 132( Issue 22) pp:
Publication Date(Web):
DOI:10.1002/app.41990
ABSTRACT
Aluminum-doped zinc oxide (AZO) conductive powders were successfully obtained through an attractive method based on the pyrolysis of coprecipitated precursors in arc plasma processing. The as-prepared powders were characterized by the x-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis spectrum. The results reveal that Al atoms are doped into ZnO lattice successfully and all the samples are polycrystalline with a hexagonal wurtzite structure. Moreover, the particle size of aluminum doped zinc oxide prepared from the plasma pyrolysis was smaller than conventional thermal calcination. Afterward, the synthesized powders were reinforced into polypropylene (PP) matrix and the dispersion of the AZO filler in the PP matrix was observed by SEM. In addition, the effect of AZO concentrations on the electrical and mechanical properties of PP composites was investigated via resistance measurement, tensile and impact tests, respectively. The results show that the electrical and mechanical properties depend on the concentration and dispersion of AZO nanoparticles in the matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41990.
Co-reporter:F. Wang, Y. Zhang, B.B. Zhang, R.Y. Hong, M.R. Kumar, C.R. Xie
Composites Part B: Engineering 2015 Volume 83() pp:66-74
Publication Date(Web):15 December 2015
DOI:10.1016/j.compositesb.2015.08.049
Acrylonitrile–butadiene–styrene (ABS)/ethylene–propylene–diene monomer (EPDM) composites reinforced with graphene nanoplatelets (GN) were fabricated by the direct melt blending, dried premixing and wet premixing process, respectively. The electrical resistivity, tensile strength, impact strength, microstructure, thermal stability, glass transition temperature and morphology of fracture surface of composites were investigated. In case of direct melt blending process, the maximum tensile strength with minimum impact strength is obtained. But this result is reversed while the fabrication of composites by wet premixing process. SEM results show that GN is prior to distributing in the continuous ABS phase. The percolation threshold could be significantly decreased from 11.8 wt% to 6.6 wt% when prepare composites by wet/dried premixing process instead of melt blending.
Co-reporter:Jianrong Liu, Xianjun Wang, Xia Tang, Ruoyu Hong, Yaqiong Wang, Wenguo Feng
Particuology 2015 Volume 22() pp:134-144
Publication Date(Web):October 2015
DOI:10.1016/j.partic.2014.04.021
•Carbonyl iron/strontium hexaferrite (SrFe12O19) magnetorheological fluids (MRFs) were prepared.•Stability of carbonyl iron-based MRFs was improved remarkably by adding SrFe12O19 nanoparticles.•MRF's shear stress could be predicted using improved Herschel–Bulkley model.•A theoretical model was proposed to predict MRF's yield stress under an applied magnetic field.The heat transfer oil-based magnetorheological fluid (MRF) was prepared using oleic acid-modified micron carbonyl iron powder as a magnetic dispersed phase and strontium hexaferrite (SrFe12O19) nanoparticles as an additive. The sedimentation stability of MRFs was studied. The results indicated that the stability of MRFs was improved remarkably by adding SrFe12O19 nanoparticles and the sedimentation ratio was only 0.88 in 20 days when the content of nanoparticles reached 10 wt%. The rheological properties were characterized by a HAAKE rheometer without a magnetic field and a capillary rheometer with and without a magnetic field. The effects of SrFe12O19 nanoparticles, the temperature, and magnetic field strength were investigated. In addition, the rheological properties could be predicted well using the improved Herschel–Bulkley model, even under a magnetic field. A theoretical model was also proposed to predict the yield stress based on the microstructure of the MRF under an applied magnetic field.
Co-reporter:Q. Chen, R.Y. Hong, W.G. Feng
Journal of Alloys and Compounds 2014 Volume 609() pp:274-283
Publication Date(Web):5 October 2014
DOI:10.1016/j.jallcom.2014.04.177
•Ba0.5Sr0.5TiO3 was synthesized through the method of co-precipitation.•Inexpensive TiOSO4 was used as raw material.•The molten salt contributes to better crystal morphology.•Composites with modified particles showed good thermal and dielectric properties.Pure perovskite phase Ba0.5Sr0.5TiO3 powders were synthesized by facile co-precipitation using inexpensive TiOSO4 as the raw material. The post-calcining treatment was at the low temperature of 950 °C, which was about 200 °C lower than that of the conventional solid-state method. The effects of two types of precipitation agents on the properties of Ba0.5Sr0.5TiO3 powders were investigated, and cubic Ba0.5Sr0.5TiO3 particles were obtained at the optimal conditions. Afterwards, the obtained Ba0.5Sr0.5TiO3 ceramics were ground into fine ceramic powders, and modified with oleic acid to improve the compatibility with the polystyrene (PS) matrix. The modified ceramic powders were dispersed in PS via solution co-blending to obtain Ba0.5Sr0.5TiO3/PS composites. The structure and morphology of the Ba0.5Sr0.5TiO3/PS composites were characterized through X-ray diffraction (XRD), and scanning electron microscopy (SEM). The SEM images showed that the modified ceramic powders had good dispersion in the PS resin. Moreover, the dielectric and thermal properties of the Ba0.5Sr0.5TiO3/PS composites were investigated, and the results showed that the modified ceramic powders could enhance the dielectric constants and thermal stability of ceramic–polymer composites.
Co-reporter:J.R. Liu, R.Y. Hong, W.G. Feng, D. Badami, Y.Q. Wang
Powder Technology 2014 Volume 262() pp:142-149
Publication Date(Web):August 2014
DOI:10.1016/j.powtec.2014.04.076
•Mass production of SrFe12O19 was achieved by molten-salt-assisted coprecipitation.•The mixture of NaOH and Na2CO3 was served as a precipitant during coprecipitation.•Effect of salt amount on morphology and magnetic properties of SrFe12O19 was studied.•A comparison of the products obtained on different preparation-scales was done.Large-scale production of strontium hexaferrite (SrFe12O19) particles was successfully achieved by molten-salt-assisted coprecipitation. A mixture of sodium hydroxide and sodium carbonate was served as mixed precipitant to obtain ferrite precursors. The effects of the Fe3 +/Sr2 + molar ratio, calcination temperature, calcination time, and molten-salt amount on the formation, morphology and magnetic properties of SrFe12O19 particles were investigated. The resultant particles were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. Single-phase SrFe12O19 particles, with particle sizes of 0.8–1.2 μm, were obtained from the precursor (with a Fe3 +/Sr2 + molar ratio of 10) being calcined at 950 °C for 2 h using the mass ratio (NaCl to precursor) of 0.3. The saturation magnetization, remanent magnetization and coercivity were about 62 emu/g, 37 emu/g, and 4310 Oe, respectively. A comparison of the products obtained at different preparation-scales was also done. The results showed that it was easier to control the particle morphology using molten salt synthesis and more economical on a large-scale production.Particle sizes were predominantly dependent on the NaCl amount and it was easier to control particle morphology using molten salt synthesis. The change of particles size further influenced the magnetic properties of SrFe12O19 particles.
Co-reporter:X.Y. Liu, R.Y. Hong, W.G. Feng, D. Badami
Powder Technology 2014 Volume 256() pp:158-165
Publication Date(Web):April 2014
DOI:10.1016/j.powtec.2014.01.096
•Carbon nanoparticles were prepared by decomposition of methane using arc plasma.•Nanotubes and small spherical nanoparticles were founded in the carbon deposit.•The BET surface area and resistivity of carbon decreased with the input current.Carbon nanoparticles (CNPs) with a controlled structure were synthesized through an attractive method based on the decomposition of methane in arc plasma processing. The effects of argon and methane flow rate, electrode material, and input electronic current on the morphology and CNPs' size were studied. The size and morphology of CNPs were characterized using scanning electron microscopy and transmission electron microscopy. Surface area and microstructure were characterized through BET surface area analysis, X-ray diffraction and Raman spectroscopy. The results showed that the BET surface area and resistivity of the CNPs were decreased with increasing input electronic current.
Co-reporter:P. Zhang, R.Y. Hong, Q. Chen, W.G. Feng
Powder Technology 2014 Volume 253() pp:360-367
Publication Date(Web):February 2014
DOI:10.1016/j.powtec.2013.12.001
•Al-doped ZnO hexagonal wurtzite is obtained by an economic and facile method.•Electrical conductivity of Al-doped ZnO is related to the calcination atmosphere.•Al-doped ZnO acts as a catalyst in the presence of light.•Al-doped ZnO with excellent conductivity shows better photocatalytic activity.•·O2− and OH are the main active species for the MO degradation.Aluminum-doped zinc oxide (AZO) conductive powders have been successfully prepared by a simple chemical coprecipitation method. The obtained powders with different post-calcining atmospheres were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM/EDS), and dynamic light scattering (DLS). The resistivity-dependent photocatalytic activity was studied by degradation of methyl orange (MO) in aqueous solution. The result showed that photodegradation of methyl orange dyes obeyed the rule of a pseudo first-order kinetics reaction and the AZO photocatalytic activity was related to the resistivity under different post-calcining atmospheres.The AZO powders prepared at different post-calcining atmospheres: A) in air; B) in argon; C) in reducing atmosphere (CO). The prepared Al-doped ZnO with different post-calcining atmospheres shows the different morphologies, conductivity and photocatalytic activity.
Co-reporter:Q.L. Jiang, S.W. Zheng, R.Y. Hong, S.M. Deng, L. Guo, R.L. Hu, B. Gao, M. Huang, L.F. Cheng, G.H. Liu, Y.Q. Wang
Applied Surface Science 2014 Volume 307() pp:224-233
Publication Date(Web):15 July 2014
DOI:10.1016/j.apsusc.2014.04.018
•The folic acid-conjugated Fe3O4 nanoparticles were synthesized by amidation method.•The conjugation of folic acid was verified qualitatively by UV–vis spectrum.•We confirmed the exothermic effect of the nanoparticles in alternating magnetic field.•The nanoparticles showed targeting effect to KB cells with FA receptors over-expression.The folic acid (FA)-conjugated Fe3O4 magnetic nanoparticles (MNPs) were synthesized by co-precipitation of Fe3+ and Fe2+ solution followed by surface modification with carboxymethyl dextran (CMD) to form carboxymethyl group terminated MNPs, then FA was conjugated with the carboxyl group functionalized MNPs. The morphology and properties of obtained nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectra (UV–vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). The FA-conjugated MNPs exhibited relatively high saturation magnetization and fast magneto-temperature response which could be applied to hyperthermia therapy. To determine the accurate targeting effect of FA, we chose FA-conjugated MNPs as MRI contrast enhancement agent for detection of KB cells with folate receptor over-expression in vitro and in vivo. The results show that these magnetic nanoparticles appear to be the promising materials for local hyperthermia and MRI.
Co-reporter:F. Wang, R.Y. Hong, W.G. Feng, D. Badami, K. Zeng
Materials Letters 2014 Volume 125() pp:48-50
Publication Date(Web):15 June 2014
DOI:10.1016/j.matlet.2014.03.136
•EPDM-g-MAH and ABS-g-MAH are used as modifiers together for the first time.•The whole composite system becomes much more miscible when ABS-g-MAH is added.•The resistivity of composite decreases dramatically by adding ABS-g-MAH.•The massive addition of raw ABS significantly enhances the mechanical property.A new way has been devised to modify acrylonitrile-butadiene-styrene (ABS) using maleic anhydride (MAH) functionalized ABS and ethylene-propylene-diene rubber (EPDM) as compatibilizer and flexibilizer. The SEM micrographs and electrical analysis reveal that EPDM-g-MAH shows poor compatibility with ABS matrix, but the polymer blends become much more miscible after being compounded with ABS-g-MAH. Carbon black (CB) selectively dispersed in ABS phase increases the concentration of CB in ABS domain, which dramatically increases electrical conductivity. Moreover, with raw ABS being massively added into the blends, the mechanical properties are significantly improved while conductivity is slightly decreased.
Co-reporter:P. Zhang;R. Y. Hong;Q. Chen;W. G. Feng
Journal of Materials Science: Materials in Electronics 2014 Volume 25( Issue 2) pp:678-692
Publication Date(Web):2014 February
DOI:10.1007/s10854-013-1630-3
Aluminum-doped zinc oxide (AZO) powder was successfully synthesized by coprecipitation. In comparison with other methods, coprecipitation method provides advantages such as facile, economic and environmental-benign. The effects of Al-doping concentration and post-sintering treatment on electrical conductivity of AZO were investigated. Moreover, we also studied the influences of Al-doping concentration, pH, and type of dye on the photocatalytic activity of AZO powders. The objective of this study is to obtain a set of optimum parameters that will allow for improving electrical conductivity and photocatalytic activity of the powders. Additionally, the synthesized AZO powders which had high performance were modified by silane coupling agent KH-550 and then reinforced into polypropylene (PP) matrix. In order to improve the electrical conductivity of AZO/PP composites, the effect of modified-AZO filler content on electrical conductivity of AZO/PP composites was investigated. In the vicinity of the percolation threshold (around 3 wt%), the AZO/PP composite’s resistivity decreased dramatically by several orders of magnitude.
Co-reporter:X.Y. Liu, S.W. Zheng, R.Y. Hong, Y.Q. Wang, W.G. Feng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 443() pp:425-431
Publication Date(Web):20 February 2014
DOI:10.1016/j.colsurfa.2013.11.025
•Poly(St-AA)/Fe3O4 microspheres were prepared via miniemulsion copolymerization.•The effect of crosslinker on the final particle morphology was studied.•The adsorbed weight of BSA at different adsorption time and pH were investigated.•The adsorbed weight of BSA was increased with the content of AA.Monodisperse cross-linked superparamagnetic poly(St-AA)/Fe3O4 microspheres with carboxyl group on the surface were prepared via miniemulsion copolymerization. The morphology, composition, magnetic properties, and crystalline structure of the magnetic microspheres were characterized by transmission electron microscopy, vibrating sample magnetometer, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis methods, respectively. The effect of crosslinker during polymerization on the particle morphology was studied. The relationship between the adsorbed weight of bovine serum albumin (BSA) on microspheres and adsorption time and pH was also investigated. Moreover, poly(St-AA)/Fe3O4 microspheres displayed excellent adsorption capabilities on BSA and the adsorbed weight of BSA was improved with the increasing AA content in the poly(St-AA)/Fe3O4 microspheres.
Co-reporter:K. He, R.Y. Hong, W.G. Feng, D. Badami
Powder Technology 2013 Volume 239() pp:518-524
Publication Date(Web):May 2013
DOI:10.1016/j.powtec.2013.02.041
Co-reporter:X. Tang, R.Y. Hong, W.G. Feng, D. Badami
Journal of Alloys and Compounds 2013 Volume 562() pp:211-218
Publication Date(Web):15 June 2013
DOI:10.1016/j.jallcom.2013.02.049
Strontium hexaferrite (SrFe12O19) nanoparticles were prepared using ethylene glycol (EG) assisted hydrothermal synthesis. The experimental results revealed that the reaction temperature and the amount of EG had an effect on the size, morphology and magnetic properties of SrFe12O19 nanoparticles. SrFe12O19 nanoparticles with a size of about 25 nm were obtained at 140 °C for 24 h at the EG/W volumetric ratios of 1/1. The saturation magnetization of the particles was approximately 10.6 emu/g. Furthermore, SrFe12O19 nanoparticles modified by oleic acid could be dispersed in high boiling point mineral oil to form highly-concentrated magnetic fluid. The magnetic and rheological properties of magnetic fluid were investigated using a Gouy magnetic balance and a rotational rheometer, respectively. The magnetic fluid showed excellent stability in gravity field and external magnetic field, and exhibited shear-thinning behavior. Moreover, the magnetic fluid had obvious heating effect in an alternating magnetic field and had potential on hyperthermia therapy of tumor.Graphical abstract.Highlights► SrFe12O19 nanoparticles with 25 nm were obtained using EG assisted hydrothermal method. ► SrFe12O19 nanoparticles were modified by oleic acid to form stable magnetic fluid. ► The magnetic fluid had obvious heating effect in an alternating magnetic field.
Co-reporter:Z. Luo;X. Cai;R. Y. Hong;J. H. Li;D. G. Wei;G. H. Luo;H. Z. Li
Journal of Applied Polymer Science 2013 Volume 127( Issue 6) pp:4756-4763
Publication Date(Web):
DOI:10.1002/app.37986
Abstract
To increase the applicability of multiwalled carbon nanotubes (MWCNTs), functional groups were generated on the generally inert surface of MWCNTs using gliding arc (GA) plasma. MWCNTs were modified using plasma polymerization with styrene (St) as monomer. The surface compositional and structural changes that occur on MWCNTs were investigated using FT-IR, Raman spectroscopy, BET surface area, and elemental analysis. Dispersion of the treated MWCNTs in different solvents was evaluated. Transmission electron microscopy images showed that the plasma-treated MWCNTs had a better dispersion than the untreated ones in nonpolar solvents. Subsequently, MWCNTs-reinforced polypropylene (PP) composites were prepared by internal batch mixing with the addition of 1.0 wt % MWCNTs. The morphology of MWCNTs/PP nanocomposites was studied through scanning electron microscopy. Observations of SEM images showed that the plasma-treated MWCNTs had a better dispersion than the untreated MWCNTs either on the composite fracture surfaces or inside the PP matrix. Moreover, the mechanical tests showed that the tensile strength and elongation at break were improved with the addition of polystyrene-grafted MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:S.W. Zheng, G. Liu, R.Y. Hong, H.Z. Li, Y.G. Li, D.G. Wei
Applied Surface Science 2012 Volume 259() pp:201-207
Publication Date(Web):15 October 2012
DOI:10.1016/j.apsusc.2012.07.019
Abstract
The PEI-CMD-MNPs were successfully prepared by the surface modification of magnetic Fe3O4 nanoparticles with carboxymethyl dextran (CMD) and polyethyleneimine (PEI). The PEI-CMD-MNPs polyplexes exhibited a typical superparamagnetic behavior and were well stable over the entire range of pH and NaCl concentration. These PEI-CMD-MNPs were used as magnetic gene vectors for targeting gene delivery.
The prepared MNPs at different surface modification stages were characterized using Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emissions canning electron microscopy (FE-SEM), powder X-ray diffraction (XRD) and dynamic laser light scattering (DLS) analysis. The magnetic properties were studied by vibrating sample magnetometer (VSM).
To evaluate the performance of the magnetic nanoparticles as gene transfer vector, the PEI-CMD-MNPs were used to delivery green fluorescent protein (GFP) gene into BHK21 cells. The expression of GFP gene was detected by fluorescence microscope. DNA-PEI-CMD-MNPs polyplexes absorbed by the cells were also monitored by Magnetic resonance imaging (MRI). The transfection efficiency and gene expression efficiency of that transfected with a magnet were much higher than that of standard transfection.
Co-reporter:X. Tang, Y.M. Wang, Z. Luo, L.S. Wang, R.Y. Hong, W.G. Feng
Progress in Organic Coatings 2012 Volume 75(1–2) pp:124-130
Publication Date(Web):September–October 2012
DOI:10.1016/j.porgcoat.2012.04.006
Strontium hexaferrite nanoparticles (NPs) were prepared by co-precipitation of strontium and ferric ions in sodium hydroxide solution. The SrFe12O19 NPs were characterized by X-ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. SrFe12O19 NPs with perfect crystal structure, nanometer size, high saturation magnetization and coercivity were obtained. Afterwards, strontium hexaferrite nanoparticles were dispersed in polyester–polyurethane solution to prepare magnetic coatings (MCs) via solution blending. The magnetic and rheological properties of magnetic coatings were measured by Gouy magnetic balance and rotational rheometer, respectively. Furthermore, the mechanical, thermal properties and physical properties of magnetic films were also investigated. The results showed that magnetic films with superior mechanical properties could be obtained with the addition of 27 wt% magnetic powders.Highlights► SrFe12O19 NPs with high saturation magnetization and coercivity were obtained. ► The magnetic coatings have good stability under magnetic field and gravity field. ► The thermal and mechanical properties of magnetic films were improved.
Co-reporter:L.S. Wang, H.F. Lu, R.Y. Hong, W.G. Feng
Powder Technology 2012 Volume 224() pp:124-128
Publication Date(Web):July 2012
DOI:10.1016/j.powtec.2012.02.039
Co-reporter:Z. Luo, R.Y. Hong, H.D. Xie, W.G. Feng
Powder Technology 2012 Volume 218() pp:23-30
Publication Date(Web):March 2012
DOI:10.1016/j.powtec.2011.11.023
Functionally modified silica nanoparticles were synthesized by a one-step method, based on the hydrolysis of tetraethyl orthosilicate in aqueous alcohol solutions with the addition of 3-methacryloyloxypropyl trimethoxy silane. The effects of the surfactant, water and ammonia concentration, and reaction temperature on the morphology and particles' size of silica were studied. The particles' size and size distribution of silica were characterized using transmission electron microscopy, scanning electron microscopy and dynamic light scattering. Monodisperse, spherical, functional silica nanoparticles were obtained at the optimal conditions. Afterwards, silica nanoparticles were dispersed in polyurethane (PU) coatings via solution blending to reinforce PU. The thermal and mechanical properties of PU films were measured by thermogravimetric analysis and universal testing machine, respectively. The results showed that the thermal and mechanical properties of PU films were improved with the addition of the modified silica nanoparticles.Functionally modified silica nanoparticles were synthesized by the hydrolysis of TEOS with the in-situ modification using MPMS. Monodisperse, spherical, modified silica nanoparticles were obtained at the optimal conditions. Then, silica nanoparticles were dispersed in polyurethane (PU) coatings to reinforce PU. The mechanical and thermal properties of PU films reinforced by modified silica nanoparticles were enhanced remarkably.Highlights► This method introduced organic functional groups onto the surface of silica. ► Monodisperse, spherical, modified silica could be obtained at the optimal conditions. ► The mechanical and thermal properties of PU films were enhanced remarkably.
Co-reporter:Zhi Luo;Yiming Wang;Ruoyu Hong;Hongzhong Li
Chinese Journal of Chemistry 2012 Volume 30( Issue 4) pp:854-860
Publication Date(Web):
DOI:10.1002/cjoc.201280025
Abstract
Fe3O4 nanoparticles (NPs) were prepared by the co-precipitation of Fe3+ and Fe2+ with ammonium hydroxide, and were modified by four different surfactants. The modified Fe3O4 NPs were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. Then, the modified Fe3O4 NPs were dispersed in ethiodized-oil by mechanical agitation and ultrasonic vibration to obtain stable Fe3O4/ethiodized-oil magnetic fluids (MFs). The magnetic properties and rheological properties of the MFs were measured using a Gouy magnetic balance and a rotational rheometer, respectively. The saturation magnetization of the Fe3O4 modified by oleic acid was 52.1 emu/g. Furthermore, the result showed that the inductive heating effect of oleic acid stabilized Fe3O4/ethiodized-oil MF was remarkable and it only took 650 s for the temperature rising from 25°C to 65°C. The specific absorption rate of the MF was 50.16 W/(g of Fe). It had a potential application in arterial embolization hyperthermia.
Co-reporter:H.F. Lu, R.Y. Hong, L.S. Wang, H.D. Xie, S.Q. Zhao
Materials Letters 2012 Volume 68() pp:237-239
Publication Date(Web):1 February 2012
DOI:10.1016/j.matlet.2011.10.049
Antimony-doped tin oxide (ATO) nanorods with tetragonal rutile structure were obtained by calcining coprecipitated precursors with sodium metasilicate nonahydrate and sodium chloride. The as-prepared ATO crystals displayed a rod-like shape. With the increase of Sb-doping concentration, the amount of nanorods decreased and the length of the rod got shorter, while the diameter changed little. When the doping amount reached at n(Sb)/n(Sn) = 5%, the nanorods became quite small (ca. 9 nm in diameter, ca. 25 nm in length). The effect of Sb doping content on the electrical resistivity was also investigated. The electrical resistivity of ATO nanopowders shows a significant decrease just only adding a small amount of Sb doping content. When the Sb doping content reached 5 mol%, the minimum electrical resistivity (0.8 Ω·cm) was obtained.Highlights► ATO nanorods were prepared via co-precipitation method. ► The effect of Sb doping content on the resistivity was investigated. ► The minimum electrical resistivity (0.8 Ω·cm) was observed for 5 mol% antimony.
Co-reporter:Yi-ming Wang 王益明;Jian-hua Li 李建华 洪若瑜
Journal of Central South University 2012 Volume 19( Issue 4) pp:863-868
Publication Date(Web):2012 April
DOI:10.1007/s11771-012-1084-4
In order to synthesize ZnO nanoparticles economically, industrial-grade zinc sulfate and urea were utilized to synthesize ZnO precursors in a stirred-tank reactor or a Teflon-lined autoclave at 100–180 °C under complete sealing condition. The ZnO precursors were calcined at 450 °C for 3 h to synthesize ZnO nanoparticles. The composition of the precursors and the formation mechanism of ZnO were studied by thermogravimetric analysis and Fourier transform infrared spectroscopy. The results of X-ray diffraction, transmission electron microscopy and scanning electron microscopy of the ZnO powders demonstrate that high-purity zincite ZnO nanoparticles are synthesized. Orthogonal experiments were performed to find out the optimal conditions for the maximum yield and the minimum size. The effect of temperature on the size of ZnO nanoparticles was investigated. The results show that a higher temperature is propitious to obtain smaller nanoparticles.
Co-reporter:H.J. Chen, Y.M. Wang, J.M. Qu, R.Y. Hong, H.Z. Li
Applied Surface Science 2011 Volume 257(Issue 24) pp:10802-10807
Publication Date(Web):1 October 2011
DOI:10.1016/j.apsusc.2011.07.103
Abstract
Stable silicon oil based ferrofluid was prepared in the present investigation. Silicon oil surfactant ethoxy terminated polydimethylsiloxane was used to modify the Fe3O4 nanoparticles. The Fe3O4 nanoparticles were firstly coated with a SiO2 layer by the hydrolysis of tetraethoxysilane. Then using the active hydroxyl groups on the surface of the SiO2, silicon oil surfactant was covalently grafted onto the Fe3O4 nanoparticles surface. The ethoxy terminated polydimethylsiloxane has similar molecular chain structure and good compatibility with that of the carrier liquid, thus ensuring stable dispersion of modified Fe3O4 in the carrier silicon oil. The interaction between Fe3O4 and the modifier was characterized by IR and XPS. The crystal structure and the magnetic properties of the Fe3O4 nanoparticles were determined by XRD and VSM, respectively. The size and morphology of the particles were observed using TEM. The properties of the silicon oil based ferrofluid were characterized by Gouy magnetic balance. The results indicated that the ferrofluid had high magnetism and good stability. The rheological properties and thermostability of the ferrofluid were also investigated.
Co-reporter:G. Liu, R.Y. Hong, L. Guo, Y.G. Li, H.Z. Li
Applied Surface Science 2011 Volume 257(Issue 15) pp:6711-6717
Publication Date(Web):15 May 2011
DOI:10.1016/j.apsusc.2011.02.110
Abstract
Superparamagnetic nanoparticles functionalized with carboxymethyl dextran (CM-dextran) were synthesized by a two-step method. First, the magnetic nanoparticles (MNPs) coated with dextran (Mw ≈ 20000) were prepared by co-precipitation of Fe2+ and Fe3+ ions. Then, dextran on the surface of MNPs reacted with monochloroacetic acid (MCA) in alkaline condition. The influences of temperature and reactant concentration on the amount of –COOH on the surface of nanoparticles were systematically studied. The obtained MNPs coated with CM-dextran were stable over the entire range of pH and NaCl concentration. The MRI experiment indicated that the CM-dextran MNPs could potentially be used as MRI contrast agents for magnetic resonance molecular imaging.
Co-reporter:H.F. Lu, R.Y. Hong, H.Z. Li
Journal of Alloys and Compounds 2011 Volume 509(Issue 41) pp:10127-10131
Publication Date(Web):13 October 2011
DOI:10.1016/j.jallcom.2011.08.058
Strontium ferrite (SrFe12O19) particles were prepared by co-precipitation method. The ferrite precursors were produced from aqueous mixtures of ferric chloride and strontium nitrate by co-precipitation, using 3 mol/L sodium hydroxide aqueous solutions as precipitant. Three surfactants sodium dodecyl sulfate (SDS), polyethylene glycol 6000 (PEG-6000), cetyltrimethylammonium bromide (CTAB), were applied and the influence of surfactants on the properties of the strontium ferrite particles was studied. The ferrite precursors were first precalcined in a muffle furnace at 400 °C and then mixed with KCl and NaCl using a planetary milling machine in order to lower the calcination temperature. Subsequently the mixtures were calcined at various temperatures. Structure and magnetic properties of the particles were characterized by X-ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. In this paper, effects of Fe3+/Sr2+ mole ratio were first verified and annealing temperatures were then discussed. The results show the strontium ferrite phase begins to form at 650 °C and complete at 800 °C after calcination, and the particles prepared using CTAB exhibit the best properties with respect to particle size and dispersibility.Highlights► Three surfactants SDS, nonionic surfactant (PEG-6000), CTAB, were applied. ► The ferrite precursors were calcinated with KCl and NaCl in order to lower the calcination temperature. ► The effects of Fe3+/Sr2+ mole ratio were first verified and annealing temperatures were then discussed.
Co-reporter:G. Liu, R.Y. Hong, L. Guo, G.H. Liu, B. Feng, Y.G. Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 380(1–3) pp: 327-333
Publication Date(Web):
DOI:10.1016/j.colsurfa.2011.03.006
Co-reporter:Wei Zhang, Fenglei Shen, Ruoyu Hong
Particuology 2011 Volume 9(Issue 2) pp:179-186
Publication Date(Web):April 2011
DOI:10.1016/j.partic.2010.07.025
Ferromagnetic Fe3O4 nanoparticles were synthesized and then self-assembled into microparticles via a solvothermal method, using FeCl3·6H2O as the iron source, sodium oleate as the surfactant, and ethylene glycol as the reducing agent and solvent. The obtained Fe3O4 microparticles were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and vibrating sample magnetometer (VSM). The size and morphology of the particles were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The Fe3O4 microparticles of nearly monodisperse diameters, controllable in the range of 120–400 nm, consist of assemblies of Fe3O4 nanoparticles with a diameter of 22 nm. The effects of reaction time, amount of surfactant and NaAc on the products were discussed. Interestingly, by using the pre-synthesized Fe3O4 microparticles as the growth substrates, spherical and smooth-looking Fe3O4 microparticles with average diameter of 1 μm were obtained. A plausible formation process was discussed.Ferromagnetic Fe3O4 nanoparticles were synthesized and then self-assembled into microparticles via a solvothermal method. The Fe3O4 microparticles of nearly monodisperse diameters consist of assemblies of Fe3O4 nanoparticles of diameter 22 nm. Interestingly, by using the pre-synthesized Fe3O4 microparticles as the growth substrates, spherical and smooth-looking Fe3O4 microparticles with average diameter of 1 μm were obtained.
Co-reporter:Jian-hua LI, Ruo-yu HONG, Guo-hua LUO, Ying ZHENG, Hong-zhong LI, Dong-guang WEI
New Carbon Materials 2010 Volume 25(Issue 3) pp:192-198
Publication Date(Web):June 2010
DOI:10.1016/S1872-5805(09)60026-3
Carbon nanotubes filled with magnetic materials are very interesting as new materials for applications in biomedicine. A simple and efficient method was developed to encapsulate Fe3O4 nanoparticles in multiwalled carbon nanotubes (MWCNTs). Transmission and scanning electron microscopy, energy dispersive X-ray analysis, and X-ray powder diffraction measurements confirmed that the Fe3O4 nanoparticles are encapsulated in the MWCNTs. The magnetic properties of the MWCNTs and the Fe3O4-filled MWCNTs were measured using a vibrating sample magnetometer. Results showed that the Fe3O4-filled MWCNTs exhibited superparamagnetism at room temperature and possessed a higher saturation magnetization (Ms) (around 13.15 emu/g) than that of the unfilled ones (around 0.35 emu/g). The MWCNTs encapsulating Fe3O4 nanoparticles have potential applications in engineering and medicine.
Co-reporter:Ruo-Yu Hong, Jian-Hua Li, Shi-Zhong Zhang, Hong-Zhong Li, Ying Zheng, Jian-min Ding, Dong-Guang Wei
Applied Surface Science 2009 Volume 255(Issue 6) pp:3485-3492
Publication Date(Web):1 January 2009
DOI:10.1016/j.apsusc.2008.09.071
Abstract
Fe3O4 magnetic nanoparticles (MNPs) were synthesized by the co-precipitation of Fe3+ and Fe2+ with ammonium hydroxide. The sodium citrate-modified Fe3O4 MNPs were prepared under Ar protection and were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM). To improve the oxidation resistance of Fe3O4 MNPs, a silica layer was coated onto the modified and unmodified MNPs by the hydrolysis of tetraethoxysilane (TEOS) at 50 °C and pH 9. Afterwards, the silica-coated Fe3O4 core/shell MNPs were modified by oleic acid (OA) and were tested by IR and VSM. IR results revealed that the OA was successfully grafted onto the silica shell. The Fe3O4/SiO2 core/shell MNPs modified by OA were used to prepare water-based ferrofluids (FFs) using PEG as the second layer of surfactants. The properties of FFs were characterized using a UV–vis spectrophotometer, a Gouy magnetic balance, a laser particle size analyzer and a Brookfield LVDV-III+ rheometer.
Co-reporter:J.H. Li, R.Y. Hong, M.Y. Li, H.Z. Li, Y. Zheng, J. Ding
Progress in Organic Coatings 2009 Volume 64(Issue 4) pp:504-509
Publication Date(Web):March 2009
DOI:10.1016/j.porgcoat.2008.08.013
Polyurethane-based coatings reinforced by ZnO nanoparticles (about 27 nm) were prepared via solution blending. The ZnO/PU films and coats were fabricated by a simple method of solution casting and evaporation. The mechanical properties of the films were investigated by a universal material test, and the abrasion resistance of the prepared coats was evaluated by a pencil-abrasion-resistance tester. It was found that significant improvement of the PU films in Young’s modulus and tensile strength was achieved by incorporating ZnO nanoparticles up to 2.0 wt%, and that the abrasion resistance of the PU coats was greatly enhanced due to the addition of ZnO nanoparticles. Moreover, the antibacterial property test was carried out via the agar dilution method and the result indicated that PU films doped with ZnO nanoparticles showed excellent antibacterial activity, especially for Escherichia coli.
Co-reporter:R.Y. Hong, J.H. Li, L.L. Chen, D.Q. Liu, H.Z. Li, Y. Zheng, J. Ding
Powder Technology 2009 Volume 189(Issue 3) pp:426-432
Publication Date(Web):13 February 2009
DOI:10.1016/j.powtec.2008.07.004
ZnO nanoparticles were synthesized by calcination of precursor prepared by the precipitation method. Polystyrene was grafted onto the surface of ZnO nanoparticles to improve the dispersion of the particles and to reduce their photocatalytic activity. The obtained particles were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. The photocatalytic activity of bare and modified ZnO nanoparticles was studied. The influence of surface modification on the photocatalytic degradation of methyl orange has been analyzed. The composition of residual solution was determined through high performance liquid chromatography. Experimental results show that well dispersed ZnO nanoparticles were obtained after surface modification. ZnO nanoparticles possess high photocatalytic activity, whereas the photocatalytic activity can be significantly reduced when polystyrene was grafted onto the particle surface.The photocatalytic activity of bare and modified ZnO nanoparticles was studied. The influence of surface modification on the photocatalytic degradation of methyl orange has been analyzed. Experimental results show that ZnO nanoparticles possess high photocatalytic activity, whereas the photocatalytic activity can be significantly reduced when polystyrene was grafted onto the particle surface.
Co-reporter:Y.J. Wu, R.Y. Hong, L.S. Wang, G.Q. Di, H.Z. Li, B. Xu, Y. Zheng, D.G. Wei
Journal of Alloys and Compounds 2009 Volume 481(1–2) pp:96-99
Publication Date(Web):29 July 2009
DOI:10.1016/j.jallcom.2009.03.060
Bi-substituted yttrium iron garnet (Bi-YIG, Bi1.8Y1.2Fe5O12) nanoparticles were successfully synthesized by molten-salt method in NaCl–KCl flux at 650 °C. Subsequently, X-ray powder diffraction, scanning electron microscopy, dynamic light scattering and vibrating sample magnetometer tests were used to characterize the phase, morphology, size distribution and magnetic properties of the as-prepared Bi-YIG nanoparticles, respectively. Moreover, the transparence and Faraday rotation of the PMMA slices filled with Bi-YIG nanoparticles were investigated by ultraviolet–visible spectrophotometer and Faraday rotation meter, respectively.
Co-reporter:B. Feng, R.Y. Hong, Y.J. Wu, G.H. Liu, L.H. Zhong, Y. Zheng, J.M. Ding, D.G. Wei
Journal of Alloys and Compounds 2009 Volume 473(1–2) pp:356-362
Publication Date(Web):3 April 2009
DOI:10.1016/j.jallcom.2008.05.094
Ultrasmall magnetite nanoparticles were prepared by using chitosan–polyacrylic acid (CS–PAA) nanospheres as template. The CS–PAA hollow nanospheres could be prepared by polymerization of acrylic acid monomers in the presence of chitosan. The Fe3O4 loading was done by dissolving FeCl3·6H2O and FeSO4·7H2O into CS–PAA nanospheres solution followed by adding NH4OH. In finally, CS–PAA template could be removed by adjusting with HCl to pH < 1. The obtained particles were characterized by dynamic light scattering (DLS) in aqueous solution and observed by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray. The results revealed that the Fe3O4 nanoparticles were 3–5 nm in size with excellent dispersibility. From the magnetometer measurements data, the particles exhibited superparamagnetic property with saturation magnetizations of 40.7 emu/g. The MRI experiment on living rabbit showed that nanoparticles prepared by the current synthetic approach had a significant magnetic resonance signal enhancement in T2-weighted image of lymph nodes.
Co-reporter:H. P. Fu;R. Y. Hong;Y. J. Zhang;H. Z. Li;B. Xu;Y. Zheng;D. G. Wei
Polymers for Advanced Technologies 2009 Volume 20( Issue 2) pp:84-91
Publication Date(Web):
DOI:10.1002/pat.1226
Abstract
Hybrid materials based on silicic acid and polymethyl methacrylate (PMMA) were prepared by in situ bulk polymerization of a silicic acid sol and MMA mixture. Silicic acid sol was obtained by tetrahydrofuran (THF) extraction of silicic acid from water. Silicic acid was prepared by hydrolysis and condensation of sodium silicate in the presence of 3.6 M HCl. As a comparative study, PMMA composites filled by silica particles, which were derived from calcining the silicic acid gel, were prepared by a comparable in situ polymerization. Each set of PMMA/silica composites was subjected to thermal and mechanical studies. Residual THF in PMMA/silicic acid composites impacted the properties of the polymer composites. With increase in silica content, the PMMA composites filled with silica particles showed improved thermal and mechanical properties, whereas a decrease in thermal stability and mechanical strength was found for PMMA composites filled with silicic acid dissolved in THF. With a better compatibility with polymer matrix, silicic acid sol shows better reinforcement than silica particles in PMMA films prepared via blending of the corresponding THF solutions. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:R. Y. Hong;B. Feng;X. Cai;G. Liu;H. Z. Li;J. Ding;Y. Zheng;D. G. Wei
Journal of Applied Polymer Science 2009 Volume 112( Issue 1) pp:89-98
Publication Date(Web):
DOI:10.1002/app.29403
Abstract
Magnetic poly(methyl methacrylate) (PMMA) microspheres were prepared by double-miniemulsion polymerization. First, oleic acid coated magnetite particles synthesized by means of coprecipitation were dispersed into octane to obtain a ferrofluid. The ferrofluid and MMA were emulsified to form O/W emulsion, respectively. Subsequently two miniemulsions were mixed together for polymerization. The obtained magnetic polymer particles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and thermogravimetry. The results showed that oleic acid coated magnetite particles were well encapsulated in PMMA. The effects of initiator dosage and monomer concentration on the conversion of MMA were also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:J.H. Li, R.Y. Hong, H.Z. Li, J. Ding, Y. Zheng, D.G. Wei
Materials Chemistry and Physics 2009 Volume 113(Issue 1) pp:140-144
Publication Date(Web):15 January 2009
DOI:10.1016/j.matchemphys.2008.07.054
In this paper, the magnetic properties of Fe3O4 nanoparticles at different temperatures were investigated. It was found that the magnetism of Fe3O4 nanoparticles vanished at 550 °C when exposed in the atmosphere for 2 h. X-ray diffractometer, Fourier transform infrared spectroscope and scanning electron microscope were employed to explain the change of magnetism of Fe3O4 nanoparticles. The route of phase transitions from Fe3O4 to α-Fe2O3 along with the increasing temperature was brought out. In order to maintain the magnetism of Fe3O4 nanoparticles at a higher temperature, a simple method was introduced to deposit BaSO4 shell on the Fe3O4 cores to prepare Fe3O4/BaSO4 multi-core/shell particles. The magnetism of Fe3O4/BaSO4 multi-core/shell particles did not vanish till 750 °C. The change of magnetism of Fe3O4/BaSO4 multi-core/shell particles was proved to be related to the appearance of “holes” on the surfaces of BaSO4 shells.
Co-reporter:R.Y. Hong, H.P. Fu, G.Q. Di, Y. Zheng, D.G. Wei
Materials Chemistry and Physics 2008 Volume 108(Issue 1) pp:132-141
Publication Date(Web):15 March 2008
DOI:10.1016/j.matchemphys.2007.09.014
Maghemite (γ-Fe2O3) nanoparticles (NPs) homogeneously dispersed in silica matrix were obtained via a three-step chemical procedure at mild conditions. The acid-treated solids were obtained using silica NPs, Fe(NO3)3·9H2O and acetic acid. The nanocomposites with various contents of maghemite were prepared by heating the acid-treated solids at 80 °C for 2 h and then at 400 °C for 1 h. The acid-treated solids were studied by means of Fourier Transform infrared spectroscopy (FT-IR) and thermogravimetry (TG). The morphology and particle size of the magnetic nanocrystallites were evaluated by the transmission electron microscopy (TEM) technique, while the nature of the obtained nanocomposites was studied using X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM), showing that the acid treatment played a critical role for the magnetic-phase formation and the maximum saturation magnetization (Ms) of the obtained nanocomposite was 37.78 emu g−1. However, when FeCl3·6H2O was used as precursor instead of Fe(NO3)3·9H2O, pure hematite (α-Fe2O3) particles dispersed in silica matrix were obtained. Magnetic fluid (MF) was prepared using the maghemite/silica nanocomposites by high-energy ball milling and was characterized by UV–vis, Gouy magnetic balance and rotating rheometer.
Co-reporter:Zhiqiang Ren, Yanping Han, Ruoyu Hong, Jianmin Ding, Hongzhong Li
Particuology 2008 Volume 6(Issue 3) pp:191-198
Publication Date(Web):June 2008
DOI:10.1016/j.partic.2008.01.004
The design of a pressurized capillary rheometer operating at prescribed temperature is described to measure the viscosity of magnetic fluids (MFs) containing Fe3O4 magnetic nanoparticles (MNPs). The equipment constant of the rheometer was obtained using liquids with predetermined viscosities. Experimentally measured viscosities were used to evaluate different equations for suspension viscosities. Deviation of measured suspension viscosities from the Einstein equation was found to be basically due to the influence of spatial distribution and aggregation of Fe3O4 MNPs. By taking account of the coating layer on MNPs and the aggregation of MNPs in MFs, a modified Einstein equation was proposed to fit the experimental data. Moreover, the influence of external magnetic field on viscosity was also taken into account. Viscosities thus predicted are in good agreement with experimental data. Temperature effect on suspension viscosity was shown experimentally to be due to the shear-thinning behavior of the MFs.
Co-reporter:B. Feng, R.Y. Hong, L.S. Wang, L. Guo, H.Z. Li, J. Ding, Y. Zheng, D.G. Wei
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 328(1–3) pp:52-59
Publication Date(Web):1 October 2008
DOI:10.1016/j.colsurfa.2008.06.024
The magnetite (Fe3O4) nanoparticles (MNPs) coated with PEG diacid via covalent bonds were prepared for magnetic resonance imaging (MRI). The surface of MNPs was first coated with (3-aminopropyl) triethoxysilane (APTES) by a silanization reaction and then linked with PEG diacid via the reaction between –NH2 and –COOH to form well-dispersed surface functionalized biocompatible MNPs. The obtained nanoparticles were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetry (TG). The MNPs had an average size of 20 nm and exhibited superparamagnetism and high saturation magnetization at room temperature. In addition, PEG-6000 diacid coated Fe3O4 nanoparticles were used to perform the MRI experiments on the living rabbits with VX2 malignant tumor, the results showed that these nanoparticles appear to be a promising vehicle for MR imaging.
Co-reporter:R. Y. Hong;J. H. Li;L. L. Chen;Y. Zheng;H. Z. Li;J. Ding
Polymers for Advanced Technologies 2007 Volume 18(Issue 11) pp:901-909
Publication Date(Web):8 MAY 2007
DOI:10.1002/pat.926
The precursor of ZnO was prepared by precipitation and ZnO nanoparticles were obtained by calcination afterwards. Poly(styrene) (PSt) was grafted onto the ZnO nanoparticles in a non-aqueous suspension to reduce the aggregation among nanoparticles and to improve the compatibility between nanoparticles and the organic matter. The obtained samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), zeta potential measurement, lipophilic degree (LD) test, photocatalytic experiments, sedimentation test, and contact angle measurement. The LD of composite particles after a high-temperature treatment was stable. The photoluminescence of PSt-grafted ZnO nanoparticles was observed by naked eyes and was recorded using a digital camera. The ZnO nanoparticles were used to reinforce poly(vinylidene fluoride) (PVDF) films and the mechanical and electric properties of the films were also measured. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:R. Y. Hong;H. P. Fu;Y. J. Zhang;L. Liu;J. Wang;H. Z. Li;Y. Zheng
Journal of Applied Polymer Science 2007 Volume 105(Issue 4) pp:2176-2184
Publication Date(Web):26 APR 2007
DOI:10.1002/app.26164
Polymethyl methacrylate (PMMA) was introduced onto the surface of silica nanoparticles by particle pretreatment using silane coupling agent (γ-methacryloxypropyl trimethoxy silane, KH570) followed by solution polymerization. The modified silica nanoparticles were characterized by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Sedimentation tests and lipophilic degree (LD) measurements were also performed to observe the compatibility between the modified silica nanoparticles and organic solvents. Thereafter, the PMMA slices reinforced by silica-nanoparticle were prepared by in situ bulk polymerization using modified silica nanoparticles accompanied with an initiator. The resultant polymers were characterized by UV–vis, Sclerometer, differential scanning calorimetry (DSC). The mechanical properties of the hybrid materials were measured. The results showed that the glass transition temperature, surface hardness, flexural strength as well as impact strength of the silica-nanoparticle reinforced PMMA slices were improved. Moreover, the tensile properties of PMMA films doped with silica nanoparticles via solution blending were enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:R. Y. Hong;T. T. Pan;S. Z. Zhang;Y. P. Han;H. Z. Li;J. Ding
Journal of Applied Polymer Science 2007 Volume 106(Issue 3) pp:1439-1447
Publication Date(Web):12 JUL 2007
DOI:10.1002/app.25142
Fe3O4 magnetic nanoparticles were prepared by coprecipitation using NH3 · H2O as the precipitating agent, and were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). The compatibility between the Fe3O4 nanoparticles and water were enhanced by grafting acrylic acid onto the nanoparticle surface. FTIR, XRD, thermogravimetry (TG), and differential scanning calorimetry (DSC) were used to characterize the resultant sample. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface-modified Fe3O4 nanoparticles were investigated. Moreover, magnetic fluids (MF), prepared by dispersing the PAA grafted Fe3O4 nanoparticles in water, were characterized using UV–vis spectrophotometer, Gouy magnetic balance, and laser particle-size analyzer. The rheological characteristics of magnetic fluid were investigated using capillary and rotating rheometers. The MF was added to prepare PVA thin film to improve mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:R.Y. Hong, S.Z. Zhang, Y.P. Han, H.Z. Li, J. Ding, Y. Zheng
Powder Technology 2006 Volume 170(Issue 1) pp:1-11
Publication Date(Web):30 November 2006
DOI:10.1016/j.powtec.2006.08.017
Fe3O4 magnetic nanoparticles (MNPs) were prepared by the coprecipitation of Fe2+ and Fe3+ using ammonium hydroxide (NH4OH) as precipitating agent. Transmission electronic microscopy (TEM) showed that the particle-size is around 10 nm. X-ray powder diffraction (XRD) indicated the sole existence of inverse cubic spinel phase of Fe3O4. The surface of MNPs was coated with oleate sodium as the primary layer and polyethylene glycol 4000 (PEG-4000) as the secondary layer to improve the stability of water-based ferrofluids (FFs). The dosages of oleate sodium and PEG-4000 were found to have an important effect on increasing the solid content. Gouy magnetic balance showed that the saturation magnetization could be as high as 1.44 × 105 A/m. Laser particle-size analyzer determined the aggregate size in FFs. The Fe3O4 MNPs did not change through the preparation of FFs. Differential scanning calorimetry–thermogravimetry (DSC–TG) and Fourier transform infrared spectroscopy (FT-IR) analysis showed existence of two distinct surfactants on the particle surface. The concentrated and diluted FFs were characterized by UV-vis spectrophotometer and excellent stability was found. The rheological measurements indicated that viscosity increased with the increase of solid content and applied magnetic field, but decreased with the increase of temperature. The FFs showed the non-Newtonian behavior of shear-thinning when the solid content was high. The mechanical properties of polyvinylalcohol (PVA) thin film can be greatly improved by adding FFs.
Co-reporter:R.Y. Hong, J.Z. Qian, J.X. Cao
Powder Technology 2006 Volume 163(Issue 3) pp:160-168
Publication Date(Web):28 April 2006
DOI:10.1016/j.powtec.2006.01.015
ZnO nanoparticles were synthesized by homogeneous precipitation. To reduce the aggregation among ZnO nanoparticles, an effective surface modification method was proposed by grafting polymethyl methacrylate (PMMA) onto the ZnO particles. That is, the surface of ZnO nanoparticles was firstly treated with a KH570 silane coupling agent, which introduces functional double bonds onto the surface of ZnO nanoparticles, followed by radical grafting polymerization in non-aqueous medium. The obtained nanocomposite was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), sedimentation test, scanning electron microscopy (SEM), and X-ray powder diffraction (XRD). Results of FT-IR and TG showed that the desired polymer chains have been covalently bonded to the surface of ZnO nanoparticles. It was found that the increasing monomer concentration could increase the grafting percentage and hence promote the dispersibility. The application of some surfactant is also helpful for dispersion. The viscous properties of nano-suspensions were investigated. The ZnO/PS nanocomposite was prepared by adding PMMA-grafted ZnO into styrene monomer, followed by radical grafting polymerization. The resulted nanocomposite was characterized by TG, DSC (differential scanning calorimetry) and XRD, and the testing results indicated that thermal behaviors of PS were obviously changed.
Co-reporter:R.Y. Hong, Q.J. Guo, G.H. Luo, J.-Y. Zhang, J. Ding
Powder Technology 2003 Volume 133(1–3) pp:216-227
Publication Date(Web):30 July 2003
DOI:10.1016/S0032-5910(03)00107-4
Recent studies on jet penetration height in literature were reviewed. Double-jet penetration in fluidized beds was investigated both experimentally and numerically. The experimental investigation was performed in a 300×51 mm two-dimensional gas–solids fluidized bed with two vertical jets, and the jet penetration height was measured. Different kinds of particles were tested in turn. The numerically predicted jet penetration heights were from the solution of a hydrodynamic model describing the gas–solids fluidization. The hydrodynamic model is based on the kinetic theory for fluidization and K–εk turbulence model for gas phase. The governing partial differential equations were solved using the modified Inter Phase Slip Algorithm (IPSA) method. The formation mechanism of jets was analyzed and the interaction of two vertical jets was reconstructed using this model. Numerical results indicated that the flow pattern of a two-jet system could be classified into three categories: isolated jets, transitional jets, and interacting jets. The criterions for those flow regions were found. The effects of jet characteristics (jet velocity, nozzle width, and the distance between two jets), particle properties (particle diameter, particle sphericity, and particle density), fluidizing gas characteristics (superficial gas velocity of bed, inlet gas density, and gas viscosity), and bed height on the jet penetration height were analyzed. It was found that the dominant factors affecting the jet penetration height are jet momentum, the drag between the two phases, entrainment near the jet neck, the distance between two jets, and the superficial gas velocity. Thus, the Froude number, Reynolds number, superficial gas velocity, the distance between the two jets, and jet nozzle width are used to propose algebraic empirical equations to estimate the jet penetration height of gas–solids fluidization at different jet regions. The empirical equations were compared with published experimental data or correlations.
Co-reporter:Ruoyu Hong, Jianhua Li, Jian Wang, Hongzhong Li
China Particuology (February–April 2007) Volume 5(Issues 1–2) pp:186-191
Publication Date(Web):1 February 2007
DOI:10.1016/j.cpart.2007.01.011
Magnetic Fe3O4 nanoparticles were prepared by means of coprecipitation using NH3·H2O in water and in alcohol, and using NaOH in water. A series of instruments such as SEM, TEM, HRTEM, FT-IR, XRD and VSM were used to characterize the properties of the magnetic nanoparticles. The results indicated that the magnetism of Fe3O4 nanoparticles synthesized using NH3·H2O in water was the highest, although the reaction time was the longest. The process using NaOH in water was the simplest and the reaction time was the shortest, but the particle characteristics were inferior to those of the other two methods. The mean size of magnetic Fe3O4 nanoparticles prepared by coprecipitation in alcohol was the smallest among the three, but the nanoparticles aggregated severely. The magnetic Fe3O4 nanoparticles were coated with oleic acid using saturated sodium oleate, and the polarity of the surface-modified nanoparticles was measured. Fe3O4 nanoparticles prepared using NH3·H2O, not NaOH, could be coated successfully and thoroughly.
Co-reporter:Ruoyu Hong, Zhiqiang Ren, Shizhong Zhang, Jianmin Ding, Hongzhong Li
China Particuology (February–April 2007) Volume 5(Issues 1–2) pp:93-102
Publication Date(Web):1 February 2007
DOI:10.1016/j.cpart.2006.12.005
Two-layer flow of magnetic fluid and non-magnetic silicone oil was simulated numerically. The continuity equation, momentum equations, kinematic equation, and magnetic potential equation were solved in two-dimensional Cartesian coordinate. PLIC (piecewise linear integration calculation) VOF (volume of fluid) scheme was employed to track the free interface. Surface tension was treated via a continuous surface force (CSF) model that ensures robustness and accuracy. The influences of applied magnetic field, inlet velocity profile, initial surface disturbance of interface and surface tension were analyzed. The computed interface shapes at different conditions were compared with experimental observation.
Co-reporter:Ruoyu Hong, Zhiqiang Ren, Jianmin Ding, M. Kawaji, Hongzhong Li
China Particuology (August 2007) Volume 5(Issue 4) pp:284-294
Publication Date(Web):1 August 2007
DOI:10.1016/j.cpart.2007.04.002
Related referential studies on gas–solid two-phase flows were briefly reviewed. Bubble ascending in a two-dimensional (2D) gas–solid fluidized bed was studied both experimentally and numerically. A modified continuum model expressed in the conservation form was used in numerical simulation. Solid-phase pressure was modeled via local sound speed; gas-phase turbulence was described by the K–ɛ two-equation model. The modified implicit multiphase formulation (IMF) scheme was used to solve the model equations in 2D Cartesian/cylindrical coordinates. The bubble ascending velocity and particle motion in the 2D fluidized bed were measured using the photochromic dye activation (PDA) technique, which was based on UV light activation of particles impregnated with the dye. Effects of bed height and superficial gas velocity on bubble formation and ascent were investigated numerically. The numerically obtained bubble ascending velocities were compared with experimental measurements. Gas bubble in jetting gas–solids fluidized bed was also simulated numerically.
Co-reporter:X. Cai, R.Y. Hong, L.S. Wang, X.Y. Wang, H.Z. Li, Y. Zheng, D.G. Wei
Chemical Engineering Journal (15 August 2009) Volume 151(Issues 1–3) pp:380-386
Publication Date(Web):15 August 2009
DOI:10.1016/j.cej.2009.03.060
A method was proposed for the preparation of silica powders using inexpensive material of sodium silicate (Na2SiO3) and carbon dioxide (CO2) by pressured carbonation, in which carbon dioxide acted as a precipitating reagent. Microstructure and size analyses of the precipitated silica powders were carried out using transmission electron microscopy and dynamic light scattering. The average particle size, size distribution and yield of silica powders were affected by reaction time, temperature and concentrations of surfactant and sodium silicate solutions. The particle size of silica powders increased with reaction temperature and concentration of sodium silicate, and the yield of silica powders increased with increasing reaction time. The size distribution of silica powders was affected by concentration of surfactant PEG. The optimal preparation conditions were experimentally determined for obtaining the silica powders with nanometer size, narrow size distribution, spherical shape and high purity without sodium carbonate and surfactant.
Co-reporter:R.Y. Hong, B. Feng, L.L. Chen, G.H. Liu, H.Z. Li, Y. Zheng, D.G. Wei
Biochemical Engineering Journal (1 December 2008) Volume 42(Issue 3) pp:290-300
Publication Date(Web):1 December 2008
DOI:10.1016/j.bej.2008.07.009
