8 results on '"Chen, Yun"'
Search Results
2. Epoxy/α-alumina nanocomposite with decreased dielectric constant and dielectric loss
- Author
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Haosheng Wang, Yang Xue, Chen Yun, Xiao-Feng Wu, Yunfa Chen, Donghai Zhang, Wu Ruiwen, and Zhong Zhang
- Subjects
010302 applied physics ,chemistry.chemical_classification ,Boehmite ,Materials science ,Nanocomposite ,Polymers and Plastics ,02 engineering and technology ,General Chemistry ,Polymer ,Epoxy ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,Dielectric spectroscopy ,chemistry ,visual_art ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Dielectric loss ,Composite material ,0210 nano-technology ,Glass transition - Abstract
In this work, the dielectric spectroscopy and dynamic mechanical thermal spectroscopy of neat epoxy and epoxy nanocomposites modified by boehmite, γ-alumina and α-alumina nanoparticles, respectively, were investigated. The dielectric behavior of epoxy resin was significantly affected by the incorporation of α-alumina nanofiller. The values of real and imaginary part of relative permittivity of epoxy/α-alumina nanocomposite were even lower than these of neat epoxy. On the contrary, these values of boehmite and γ-alumina nanocomposites were higher than these of neat epoxy. The glass transition temperature (Tg) determined by dynamic mechanical thermal analysis (DMA) was obviously decreased when boehmite nanofiller was added into the epoxy nanocomposite. The value of Tg was slightly decreased by γ-alumina and apparently increased by α-alumina nanofiller. These changes of performance may be attributed to that the existence of α-alumina nanoparticles restricted the mobility of polymer molecular chains. POLYM. COMPOS., 2016. © 2016 Society of Plastics Engineers
- Published
- 2016
3. Polymer/Ordered Mesoporous Carbon Nanocomposite Platelets as Superior Sensing Materials for Gas Detection with Surface Acoustic Wave Devices
- Author
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Chen-Yun Hsiao, Chia-Min Yang, Pei-Hsin Ku, Da-Jeng Yao, Kea-Tiong Tang, Szu-Chieh Liu, Yi-Tian Li, Mei-Jing Chen, and Tai-Hsuan Lin
- Subjects
chemistry.chemical_classification ,Materials science ,Nanocomposite ,Radical polymerization ,Surface acoustic wave ,chemistry.chemical_element ,Surfaces and Interfaces ,Polymer ,Condensed Matter Physics ,chemistry ,Chemical engineering ,Sensor array ,Electrochemistry ,Gravimetric analysis ,General Materials Science ,Mesoporous material ,Carbon ,Spectroscopy - Abstract
We have prepared nanocomposites of polymers and platelet CMK-5-like carbon and have demonstrated their superior performance for gravimetric gas detection. The zirconium-containing platelet SBA-15 was used as hard template to prepare CMK-5-like carbon, which was then applied as a lightweight and high-surface-area scaffold for the growth of polymers by radical polymerization. Mesoporous nanocomposites composed of four different polymers were used as sensing materials for surface acoustic wave devices to detect ppm-level ammonia gas. The sensors showed much better sensitivity and reversibility than those coated with dense polymer films, and the sensor array could still generate a characteristic pattern for the analyte with a concentration of 16 ppm. The results show that the nanocomposite sensing materials are promising for highly sensitive gravimetric-type electronic nose applications.
- Published
- 2012
4. Epoxy/α-alumina nanocomposite with high electrical insulation performance.
- Author
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Chen, Yun, Zhang, Donghai, Wu, Xiaofeng, Wang, Haosheng, Zhang, Chong, Yang, Wei, and Chen, Yunfa
- Abstract
An experimental study was conducted to improve the electrical insulation of epoxy resin. The effects of boehmite, γ-alumina and α-alumina nanoparticles on the volume resistivity, dielectric strength and glass transition temperature of epoxy nanocomposites were investigated. The results showed that α-alumina nanoparticles displayed obvious advantages in enhancing electrical insulation performance of epoxy nanocomposites, compared to boehmite and γ-alumina nanoparticles. The direct current volume resistivity and breakdown strength of epoxy nanocomposite with 2.0 wt% α-alumina nanoparticles was improved to 2.2 × 10 18 Ω cm and 76.1 kV mm −1 respectively. And these improved values of electrical insulation properties are much higher than these of epoxy nanocomposites reported in previous studies. The main reason of these improvements may be that the epoxy/α-alumina interaction zone was enhanced by crosslink. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
5. Magnetization behavior and magnetic viscosity in nanocomposite Pr9Fe74Co12B5Snx(x=0, 0.5) ribbons
- Author
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Shen Bao-Gen, Chen Yun-Zhong, Chen Ren-Jie, Rong Chuan-Bing, He Shu-Li, Zhang Hong-Wei, and Sun Ji-Rong
- Subjects
Magnetization ,Nanocomposite ,Materials science ,Volume (thermodynamics) ,Magnet ,Phase (matter) ,Volume fraction ,Demagnetizing field ,Analytical chemistry ,Nucleation ,General Physics and Astronomy - Abstract
Nanocomposite Pr9Fe74Co12B5 and Pr9Fe74Co12B5Sn0.5 ribbons were directly prepared by melt-spinning. Measurements of reversible and irreversible magnetization and magnetic viscosity were performed on the ribbons. It is found that the demagnetization curves of the both samples show a single hard phase behavior at room temperature, while a two-phase behavior at low temperature. The sample with Sn addition, because of its more homogeneous microstructure, shows a more obvious two-phase behavior than the Sn free one at low temperature. Furthermore, the increase of the volume fraction and grain sizes of the soft phase, in the Sn-doped ribbons, increases the portions of reversible magnetization and decreases the nucleation field Hn. The investigation of the magnetic viscosity shows that the activation volume is related to the grain sizes of the soft phase.
- Published
- 2005
6. Comparative study on the films of poly(vinyl alcohol)/pea starch nanocrystals and poly(vinyl alcohol)/native pea starch
- Author
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Chen, Yun, Cao, Xiaodong, Chang, Peter R., and Huneault, Michel A.
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POLYVINYL alcohol , *NANOCRYSTALS , *HYDROLYSIS , *FOURIER transform infrared spectroscopy , *NANOSTRUCTURED materials - Abstract
Abstract: Pea starch nanocrystals (PSN) dispersion containing nanocrystals in a range of 30–80nm was prepared from native pea starch (NPS) granules by acid hydrolysis. Two series of films were prepared by blending poly(vinyl alcohol) (PVA) with NPS and PSN, respectively. The effects of NPS and PSN on the structure and properties of the resulting films were comparatively investigated by FTIR, XRD, SEM, and testing of light transmittance, tensile, and moisture uptake. The light transmittance (Tr), tensile strength (σ b), and elongation at break (ε b) of the PVA/NPS films were lower than that of PVA film and decreased with an increase in NPS content. However, the PVA/PSN nanocomposite films containing 5 and 10wt% of PSN content exhibited improved physical properties over the PVA film. The PVA/PSN films showed higher Tr, σ b, and ε b, and lower moisture uptake (Mu) than the corresponding PVA/NPS films with the same component ration. For example, the values of Tr, σ b, ε b, and Mu of the PVA/PSN film containing 10wt% of PSN content were 91%, 40MPa, 734% and 71%, respectively; while those of the corresponding PVA/NPS film were 69%, 35MPa, 579% and 73%, respectively. The results revealed that PSN, comparing with NPS, had much smaller sizes and dispersed more homogeneously in PVA matrix, resulting in stronger interactions with PVA. New applications of native pea starch and its nanocrystals as low-cost fillers were explored in this work, and PSN exhibited greater potential than NPS to improve the properties of PVA-based composites. [Copyright &y& Elsevier]
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- 2008
- Full Text
- View/download PDF
7. A novel Ag2O/Bi2WO6 composite with enhanced piezocatalytic performance for ciprofloxacin removal.
- Author
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Liu, Bin, Sun, Li-Ying, Chen, Yun-Xuan, Su, Shi-Xin, Wang, Xiao-Fang, and Wang, Xin
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SEMICONDUCTOR materials , *CIPROFLOXACIN , *BAND gaps , *ENERGY bands , *PIEZOELECTRIC thin films , *ENVIRONMENTAL remediation , *ORGANIC semiconductors - Abstract
[Display omitted] • Piezocatalytic activity of Bi 2 WO 6 was potently improved by doping Ag 2 O. • Piezocatalytic removal rate of CIP reached 93.44 % ± 0.34 % using Ag 2 O/Bi 2 WO 6 composite. • Ag 2 O/Bi 2 WO 6 showed bright application prospects in environmental rehabilitation. Bi 2 WO 6 , an important semiconductor material, has been widely used in the catalytic degradation of organic wastewater in recent years. However, Bi 2 WO 6 owns the low band gap energy, the recombination of the produced e−-h+ pairs expected to be fast, which leads to undesirable degradation effects. In order to improve its piezocatalytic ability, this paper combined the semiconductor material Bi 2 WO 6 with Ag 2 O to form Ag 2 O/Bi 2 WO 6 piezoelectric catalysts, which was characterized and its removal effect on ciprofloxacin (CIP) was discussed. According to the analyses, the reaction rate constant for the piezocatalytic removal of CIP in the company of 5 % composite ratio of Ag 2 O/Bi 2 WO 6 was about 1.40 and 4.87 times higher than it was when Bi 2 WO 6 and piezocatalytic technology were used alone. By exploring the experimental principle, the increased piezocatalytic activity of Ag 2 O/Bi 2 WO 6 was found to be due to the creation of Z-scheme heterojunction, which could efficiently separate the e−-h+ pairs. Reuse experiments were also carried out, and the results showed that it has good reusability and stability in piezocatalysis. In summary, Ag 2 O/Bi 2 WO 6 has good piezocatalytic activity for the removal of CIP. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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8. Preparation and electrochemical properties of the ternary nanocomposite of polyaniline/activated carbon/TiO2 nanowires for supercapacitors
- Author
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Tan, Qiangqiang, Xu, Yuxing, Yang, Jun, Qiu, Linlin, Chen, Yun, and Chen, Xiaoxiao
- Subjects
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ELECTROCHEMICAL analysis , *SUPERCAPACITORS , *CHEMICAL systems , *NANOCOMPOSITE materials , *NANOWIRES , *POLYANILINES , *ACTIVATED carbon , *TITANIUM dioxide - Abstract
Abstract: We herein report the synthesis of ternary nanocomposites consisting of polyaniline (PANI), activated carbon, and TiO2(B) components, which involves the preparation of activated carbon/TiO2(B) nanowires (ACTB) using sonochemical–hydrothermal method, and their subsequent composites with PANI via in situ polymerization. The morphology and structure of ACTB/PANI ternary nanocomposites are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). Morphology analysis shows that the porous network layer of PANI homogeneously coated on the outer surface of ACTB support. The electrochemical properties of the ternary nanocomposite as the electrode material for electrochemical capacitors are examined by cyclic voltammetry and galvanostatic charge/discharge test in an organic electrolyte (1.0M LiClO4 in propylene carbonate). The results show that the ternary nanocomposites have a specific capacitance as large as 286Fg−1 in the potential range from −3 to 3V (vs. SCE) at a charge–discharge current density of 1.0Ag−1, which is a significant improvement compared to those of the three separate components, demonstrating that the ACTB/PANI nanocomposites are promising materials for supercapacitor electrode. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
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