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Yu W.,Shanghai Second Polytechnic University | Xie H.,Shanghai Second Polytechnic University | Xin S.,Shanghai Yueda New Materials Science and Technology Ltd. | Yin J.,Shanghai Yueda New Materials Science and Technology Ltd. | And 2 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2015

Thermal functional Materials have wide applications in thermal management fields, and inserting highly thermal conductive materials is effective in enhancing thermal conductivity of matrix. In this paper, copper nanoparticles were selected as the additive to prepare polymethyl methacrylate (PMMA) based nanocomposite with enhanced thermal properties. Uniform copper nanoparticles with pure face-centered lattice were prepared by liquid phase reduction method. Then, they were added into PMMA/N, N -Dimethylmethanamide (DMF) solution according to the different mass fraction for uniform dispersion. After DMF was evaporated, Cu-PMMA nanocomposites were gained. The thermal analysis measurement results showed that the decomposition temperature of nanocomposites decreased gradually with the increasing particle loadings. The thermal conductivity of the Cu-PMMA nanocomposites rose with the increasing contents of copper nanoparticles. With a 20 vol.% addition, the thermal conductivity was up to 1.2 W/m • K, a 380.5% increase compared to the pure PMMA. The results demonstrate that copper nanoparticles have great potential in enhancing thermal transport properties of polymer. © 2015 American Scientific Publishers All rights reserved.


Wu Z.-H.,Shanghai Second Polytechnic University | Xie H.-Q.,Shanghai Second Polytechnic University | Zhai Y.-B.,Shanghai Yueda New Materials Science and Technology Ltd.
Journal of Nanoscience and Nanotechnology | Year: 2015

Zinc oxide (ZnO) has attracted increasing attention as one of the most promising n -type thermoelectric materials, but its practice use was limited by high thermal conductivity and low electrical conductivity. Therefore, we herein prepared Co-doped ZnO nanoparticles by sol-gel method and then compressed nanoparticles into bulk materials through spark plasma sintering. The thermoelectric properties, including electrical conductivity, Seebeck coefficient, thermal conductivity, and ZT value, have been investigated. We found that the substitution of Co2+ causes the decrease of bandgap and the increase of carrier concentration, thus the improvement of electrical conductivity. At the same time, the Co-induced lattice distortion and nanoparticles reduce the thermal conductivity by shortening the mean free path (MFP) of the phonons. The resultant ZT is 0.037 for Zn0.-9 Co0-.1 O, which is more than 23-fold higher than that of the pure ZnO samples. Copyright © 2015 American Scientific Publishers All rights reserved.


Yu W.,Shanghai Second Polytechnic University | Xie H.,Shanghai Second Polytechnic University | Yin L.,Shanghai University | Zhao J.,Shanghai Yueda New Materials Science and Technology Ltd. | And 2 more authors.
International Journal of Thermal Sciences | Year: 2015

A remarkable synergistic effect between graphene sheets and alumina particles in improving the thermal conductive properties of the novel thermal grease is demonstrated. The use of hybrid size alumina filler leads to compact packing structure in the silicone base and hinders the aggregation of graphene to form clusters. The two-dimensional graphene with superb thermal conductivity can bridge the alumina particles to form more compact packing structure and provide faster and more effective pathways for phonon transport in thermal grease. These synergistic effects decrease the thermal boundary resistance and enhance the thermal conductivity of the thermal grease. The addition of graphene is only 1 wt.%, and the maximum thermal conductivity of the novel thermal grease is 3.45 W/m K. It is significantly improved compared with the thermal grease without graphene (2.70 ± 0.10 W/m K). With respect to the silicone base, an enhancement in thermal conductivity of 2553% is obtained. Meanwhile, a correction theoretical model is proposed by modifying Burggeman asymmetric model, and the model predictions are in reasonable agreement with the experimental values. © 2015 Elsevier Masson SAS.


Yu W.,Shanghai Second Polytechnic University | Zhao J.,Shanghai Yueda New Materials Science and Technology Ltd. | Wang M.,Shanghai Second Polytechnic University | Hu Y.,Shanghai Second Polytechnic University | And 2 more authors.
Nanoscale Research Letters | Year: 2015

Different cupric oxide (CuO) structures have attracted intensive interest because of their promising applications in various fields. In this study, three kinds of CuO structures, namely, CuO microdisks, CuO nanoblocks, and CuO microspheres, are synthesized by solution-based synthetic methods. The morphologies and crystal structures of these CuO structures are characterized by field-emission scanning electron microscope and X-ray diffractometer, respectively. They are used as thermal conductive fillers to prepare silicone-based thermal greases, giving rise to great enhancement in thermal conductivity. Compared with pure silicone base, the thermal conductivities of thermal greases with CuO microdisks, CuO nanoblocks, and CuO microspheres are 0.283, 0256, and 0.239 W/mK, respectively, at filler loading of 9 vol.%, which increases 139%, 116%, and 99%, respectively. These thermal greases present a slight descendent tendency in thermal conductivity at elevated temperatures. These experimental data are compared with Nan's model prediction, indicating that the shape factor has a great influence on thermal conductivity improvement of thermal greases with different CuO structures. Meanwhile, due to large aspect ratio of CuO microdisks, they can form thermal networks more effectively than the other two structures, resulting in higher thermal conductivity enhancement. © 2015, Yu et al.; licensee Springer.


Wu Z.-H.,Shanghai Second Polytechnic University | Xie H.-Q.,Shanghai Second Polytechnic University | Zhai Y.-B.,Shanghai Yueda New Materials Science and Technology Ltd.
Applied Physics Letters | Year: 2013

We report in this letter the synthesis and thermoelectric properties of Zn1-xNixO/polyparaphenylene (Zn1-xNi xO/PPP) organic-inorganic hybrid materials. Compared to the inorganic ZnO-based materials, hybrid materials exhibit dual effects of increased power factor consistent with the molecular junction effect and a reduction in thermal conductivity by the incorporation of conductive PPP. As a result, the greatest ZT = 0.54 of hybrid materials was obtained at 1173 K, which corresponds to a 6-fold enhancement compared to that of the best inorganic Zn 0.97Ni0.03O sample (ZT = 0.09) at 1000 K. © 2013 AIP Publishing LLC.


Yu W.,Shanghai Second Polytechnic University | Xie H.,Shanghai Second Polytechnic University | Li F.,Shanghai Yueda New Materials Science and Technology Ltd. | Zhao J.,Shanghai Yueda New Materials Science and Technology Ltd. | Zhang Z.,Beijing Institute of Technology
Applied Physics Letters | Year: 2013

The thermal conductivities of graphene oxide paper (GOP) and the alkaline earth metal ions (Mg2, Ca2) modified analogues, prepared by a facile vacuum filtration method, were measured by a laser flash method. The thermal conductivities of GOP, Mg-modified GOP, and Ca-modified GOP are 3.91 W/(m × K), 32.05 W/(m × K), and 61.38 W/(m × K), respectively, which indicate the modification of GOP with metal ions has resulted in significant enhancement in thermal conduction properties compared with unmodified GOP. The crosslink between graphene oxide sheet and metal ions, the neat stacking of graphene oxide sheets in modified GOP, together with the intercalation of metal ions into the gallery spaces between the graphene oxide sheet basal planes, result in a decrease of thermal resistance of the boundary and an increase of contact surface, thus increases the thermal conductivity of modified graphene oxide paper. © 2013 AIP Publishing LLC.


Wu Z.-H.,Shanghai Second Polytechnic University | Xie H.-Q.,Shanghai Second Polytechnic University | Zhai Y.-B.,Shanghai Yueda New Materials Science and Technology Ltd. | Gan L.-H.,Shanghai Second Polytechnic University | Liu J.,Shanghai Second Polytechnic University
Chinese Physics B | Year: 2015

In order to study the thermoelectric properties of TiO2-based hybrid materials, TiO2/polyparaphenylene (PPP) nanocomposites are fabricated by spark plasma sintering (SPS). The results show that the electrical conductivity follow percolation theory is enhanced due to the electron transfer highway provided by the conducting PPP phase. Furthermore, the thermal conductivity is reduced due to the drastic difference of vibrational spectra between organic and inorganic components. As a result, the greatest ZT = 0.24 is obtained for TiO2/0.75 wt% PPP sample, which is 15-fold higher than pure TiO2 (ZT = 0.016). © 2015 Chinese Physical Society and IOP Publishing Ltd.


Yu W.,Shanghai Second Polytechnic University | Xie H.,Shanghai Second Polytechnic University | Chen L.,Shanghai Second Polytechnic University | Zhu Z.,Shanghai Second Polytechnic University | And 2 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

Two kinds of silicone grease containing graphene nanoplatelets or reduced graphene oxide were prepared, and their thermophysical properties have been investigated. When the volume fraction was 1%, the reduced graphene oxide was the most effective additive to enhance the heat transfer properties of silicone, and graphene nanoplatelet was slightly inferior to the former. While when the concentration was enhanced, the viscosity of silicone grease containing reduced graphene oxide became very large due to its rich pore structure. Graphene nanoplatelet was efficient for the thermal conductivity enhancement of silicone grease, and it provided a thermal conductivity enhancement was up to 668% (loading of 4.25 vol.%). The experimental result is in excellent agreement with the recently developed theoretical model analyzing the thermal conductivity of isotropic composites containing randomly embedded GNPs, and it validates that graphene is an effective thermally conducting filler to let grease have high thermal conductivity with low filler content. © 2013 Elsevier B.V. All rights reserved.


Yu W.,Shanghai Second Polytechnic University | Xie H.,Shanghai Second Polytechnic University | Chen L.,Shanghai Second Polytechnic University | Zhao J.,Shanghai Yueda New Materials Science and Technology Ltd. | Li F.,Shanghai Yueda New Materials Science and Technology Ltd.
Thin Solid Films | Year: 2015

Graphene papers (GP) modified with alkaline earth metal ions (Mg2 +, Ca2 +) were prepared by reduction of graphene oxide papers, which were obtained through a facile vacuum filtration of graphene oxide solution aqueous. The thermal conductive properties of graphene paper and its modified analogues were measured with a laser flash method. The thermal diffusivities of Mg-modified GP and Ca-modified GP are 1003.4 mm2/s and 2232.2 mm2/s, respectively, which is significantly improved compared with unmodified graphene paper (694.9 mm2/s). The corresponding thermal conductivities are 100.4 W/mK (GP), 147.7 W/mK (Mg-GP) and 331.8 W/mK (Ca-GP), respectively, from which a substantial enhancement in thermal conductivity of M-modified GP is also observed. It is found that the ion chelating between carboxyl groups of graphene oxide and alkaline earth metal ions will bridge the small graphene oxide sheets, and it will decrease the thermal resistance of the boundary and increase the contact surface of graphene sheets. The reduction of M-modified graphene oxide can partly recover the structure of graphene, thus can further improve the heat transfer property of graphene paper. © 2015 Elsevier B.V. All rights reserved.


PubMed | Shanghai Yueda New Materials Science and Technology Ltd. and Shanghai Second Polytechnic University
Type: | Journal: Nanoscale research letters | Year: 2015

Different cupric oxide (CuO) structures have attracted intensive interest because of their promising applications in various fields. In this study, three kinds of CuO structures, namely, CuO microdisks, CuO nanoblocks, and CuO microspheres, are synthesized by solution-based synthetic methods. The morphologies and crystal structures of these CuO structures are characterized by field-emission scanning electron microscope and X-ray diffractometer, respectively. They are used as thermal conductive fillers to prepare silicone-based thermal greases, giving rise to great enhancement in thermal conductivity. Compared with pure silicone base, the thermal conductivities of thermal greases with CuO microdisks, CuO nanoblocks, and CuO microspheres are 0.283, 0256, and 0.239W/mK, respectively, at filler loading of 9vol.%, which increases 139%, 116%, and 99%, respectively. These thermal greases present a slight descendent tendency in thermal conductivity at elevated temperatures. These experimental data are compared with Nans model prediction, indicating that the shape factor has a great influence on thermal conductivity improvement of thermal greases with different CuO structures. Meanwhile, due to large aspect ratio of CuO microdisks, they can form thermal networks more effectively than the other two structures, resulting in higher thermal conductivity enhancement.

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