查找使用阿拉丁产品的科研文献

Enhanced thermal and mechanical properties of polypropylene composites with hyperbranched polyester grafted sisal microcrystalline

Wu Lingyan,Lu Shaorong,Pan Lulu,Luo Qiyun,Yang Jin,Hou Linglan,Li Yuqi,Yu Jinhong

Polypropylene composites were prepared by melt compounding method with hyperbranched polyester grafted sisal microcrystalline and CaCO 3 . The thermal and mechanical properties of polypropylene composites were investigated by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), melt flow indexer (MFI), dynamic mechanical analysis (DMA) and mechanical tests. It was found that the thermal and mechanical properties of PP composites were greatly improved by incorporating MCC-g-HPG-SA. For example, the impact strength, flexural strength, and toughness of the composites with 4 wt% MCC-g-HPG-SA loading were 64.71 kJ/m 2 , 42.72 MPa, and 2186.69 J/m 3 , significantly increased by 238.3 %, 18.4 % and 1843.9 % respectively, as compared with PP/MCC/CaCO 3 composites. In addition, thermal stability of PP/MCCg-HPG-SA/CaCO 3 composites also showed an obvious enhancement compared with PP/MCC/CaCO 3 composites.

Selective removal of Pb(II) ions from aqueous solutions by acrylic acid/acrylamide comonomer grafted polypropylene fibers

Guo Mulin,Chen Haonan,Luo Zhengwei,Lian Zhouyang,Wei Wuji

Polypropylene-based chelating fibers grafted with acrylic acid and acrylamide side chains were simply synthesized, and subsequently employed as adsorbents for Pb(II) removal selectively from aqueous solutions. The assynthesized fibers were characterized by elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscope, and water contact angle. The adsorption results revealed that kinetics data were fitted by a pseudo-second order model (semi-saturation time 6.2 min), thereby suggesting chelating interaction to be the main mechanism during the adsorption process. The adsorption isotherm data fitted well with a Langmuir model. The thermodynamic study revealed the adsorption of Pb(II) as an exothermic spontaneous chemisorptive process. Coexisting Na(I), Mg(II), and Al(III) in solution showed negligible effects in the adsorption process. As confirmed by carboxyl amination, the carboxylate oxygen preferentially chelates coexisting Ca(II) over Pb(II), thereby leading to lower extents of Pb(II)-O chelate interaction. The spent fibers were effectively and repetitively (five cycles) regenerated while maintaining high performance upon treatment with 1 M hydrochloric acid solutions.

Aqueous aggregation and stability of graphene nanoplatelets, graphene oxide, and reduced graphene oxide in simulated natural environmental conditions: complex roles of surface and solution chemistry

Ye Nan,Wang Zhuang,Wang Se,Fang Hao,Wang Degao

Graphene-family nanomaterials (GFNs) exhibit universal applications and consequently will inevitably enter aquatic systems. However, both the fate and behavior of GFNs in aquatic environments have not been completely explored at field relevant conditions. Herein, we have systematically investigated the aqueous aggregation and stability of graphene nanoplatelets (GNPs), graphene oxide (GO), and reduced graphene oxide (RGO) under varied solution chemistry parameters (pH, divalent cations, and dissolved organic carbon (DOC)) during 21 days of incubation in simulated natural environmental conditions. Results indicate that pH values from 6 to 9 had a notable impact on the aqueous behaviors of the three GFNs. Divalent cations (Ca 2+ and Mg 2+ ) at the concentrations of 2.5 and 10 mM remarkably increased the extent of aggregation of the three GFNs and resulted in severe sedimentation, independently of surface chemical functionalization. The presence of only DOC ranging from 0.5 to 2 mg C/L significantly elevated the dispersion stability of GNPs and RGO in a dose-dependent manner, whereas no effects were observed on GO. Furthermore, DOC at the studied concentrations and surface functionality were insufficient to counterbalance the impact of the divalent cations. Direct visual and in situ observations further supported the conclusions on the effects of divalent cations or/and DOC. These findings further underline that the environmental behaviors of GFNs are controlled by the complex interplay between water chemistry parameters and GFN surface properties.

Preparation of three-dimensional modified boron nitride and its effect on the flame-retardant performance and thermal conductivity of silicone rubber

Xu Wenzong,Fan Liangjie,Wang Jiajun,Zhang Yi,Yao Le,Qiao Mengxia

In order to make strides the fire retardancy and warm conductivity of silicone rubber (VMQ), a simple synthesis process was used to grow β -FeOOH on the surface of Boron nitride (BN) to form a three-dimensional structure. The structure and morphology of the BN- β -FeOOH hybrid were systematically characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), which proved the successful preparation of the hybrid BN- β -FeOOH. BN- β -FeOOH were added to VMQ to think about their impact on the warm solidness, combustion and warm conductivity of VMQ. Experimental results showed that the limiting oxygen index (LOI) of VMQ with three parts of BN- β -FeOOH increased to 29.8%, and the peak heat release rate (pHRR) and total heat release (THR) decreased by 34.5 and 30.2%. The flame-retardant performance of VMQ was significantly improved, and the emission of smoke was significantly reduced. At the same time, the thermal conductivity of the VMQ added with BN- β -FeOOH was also significantly improved. The improvement of its flame-retardant performance was due mainly to the physical barrier of boron nitride and the catalytic carbonization of β -FeOOH. In addition, the three-dimensional well-connected thermal conductivity network constructed by BN- β -FeOOH effectively improved the thermal conductivity of VMQ.

α-MnO2 hollow clews for rechargeable Li-air batteries with improved cyclability

Zhang LeiLei,Wang ZhongLi,Xu Dan,Xu JiJing,Zhang XinBo,Wang LiMin

Lithium-air (Li-air) batteries have attracted worldwide attention due to their high energy density (11140 Wh kg −1 ) comparable to gasoline. In this work, we have synthesized the α-MnO 2 hollow clews via a simple method and characterized them by X-ray diffraction and scanning electron microscope. Interestingly, cycle performance of Li-air batteries is improved greatly when using the α-MnO 2 hollow clews as the catalyst. The first discharge capacity is 596 mAh g −1 , and the charge capacity is 590 mAh g-1 at the current density of 0.1 mA cm −2 between 2.0 and 4.2 V using the Vulcan XC-72 as the carbon material. Additionally, by re-assembling new batteries with the used lithium foil, separators and cathode separately, we find that the cathode is the key role to end the Li-air battery life.

Boosting the Energy Density of Flexible Asymmetric Supercapacitor with Three Dimensional Fe2O3 Composite Brush Anode

Gao Yuan,Zhou Ruitao,Wang Dongrui,Huang Qiyao,Cheng Ching-Hsiang,Zheng Zijian

Flexible asymmetric supercapacitor is fabricated with three dimensional(3D) Fe 2 O 3 /Ni(OH) 2 composite brush anode and Ni(OH) 2 /MoO 2 honeycomb cathode. Particularly for 3D composite brush anode, a layer of thin Fe 2 O 3 film is firmly adhered on a 3D Ni brush current collector with the assist of Ni(OH) 2 , functioning as both adherence layer and pseudocapacitive active material. The unique 3D Ni brush current collector possesses large surface area and stretching architecture, which facilitate to achieve the composite anode with high gravimetric capacitance of 2158 F/g. In terms of cathode, Ni(OH) 2 and MoO 2 have a synergistic effect to improve the specific capacitance, and the resulting Ni(OH) 2 /MoO 2 honeycomb cathode shows a very high gravimetric capacitance up to 3264 F/g. The asymmetric supercapacitor(ASC) has balanced cathode and anode, and exhibits an ultrahigh gravimetric capacitance of 1427 F/g and an energy density of 476 Wh/kg. The energy density of ASC is 3–4 times higher than those of other reported aqueous electrolyte-based supercapacitors and even comparable to that of commercial lithium ion batteries. The device also shows marginal capacitance degradation after 1000 cycles’ bending test, demonstrating its potency in the application of flexible energy storage devices.

Author Correction: Ocular biometry and refractive outcomes using two swept-source optical coherence tomography-based biometers with segmental or equivalent refractive indices

Omoto Miki Kamikawatoko,Torii Hidemasa,Masui Sachiko,Ayaki Masahiko,Tsubota Kazuo,Negishi Kazuno

Study on microwave dielectric properties of new microwave dielectric ceramics CaNd2ZnTi2O9

He Chuansheng,Li Yingxiang,Wang Fei,Pang Xianying,Hou Zegui,Liu Wei,Liang Deyin,Tang Bin,Fang Zixuan,Shi Zitao,Chen Jingjing,Li Hao

This research demonstrates a novel class of CaNd 2 ZnTi 2 O 9 microwave dielectric ceramic using the traditional solid-state methods. Analysis by XRD and Rietveld refinement revealed that the CaNd 2 ZnTi 2 O 9 sample is single-phase and possesses an orthorhombic crystal configuration with a Pbnm (62) space group. SEM observation confirmed the double perovskite structure of CaNd 2 ZnTi 2 O 9 ceramics and the relative density of the ceramic samples reached 95.8%. Additionally, the τ f of CaNd 2 ZnTi 2 O 9 sample is affected by V Ti–O bond valence. CaNd 2 ZnTi 2 O 9 samples sintered at 1430 °C show significant microwave dielectric properties ( ε r  = 35.41, Q  ×  f  = 15,440 GHz, τ f  =  −S54.8 ppm/°C).

Enhanced performance of CdS/CdSe quantum dot-sensitized solar cells by long-persistence phosphors structural layer

Deng Yunlong,Lu Shuqi,Xu Zhiyuan,Zhang Jiachi,Ma Fei,Peng Shanglong

Light absorption plays an important role in improving the power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs). In this study, a multifunctional long-persistence phosphor (LPP) layer was introduced into the CdS/CdSe QDSSCs via a simple doctor blade method. The LPP layer can simultaneously improve the light harvesting and photo charge transfer in CdS/CdSe QDSSCs. As a result, their short-circuit current and corresponding PCE are effectively enhanced. The PCE can reach up to 5.07%, which is about 24% larger than that of the conventional CdS/CdSe QDSSCs without LPP layer. The solar cells can work in dark for a while due to the long-lasting fluorescence of the LPP layer. This research provides an effective way to improve the PCE of QDSSCs, and finds the possibility for all-weather QDSSCs.

Simple microwave synthesis and improved electrochemical performance of Nb-doped MnO2/reduced graphene oxide composite as anode material for lithium-ion batteries

Wang Xiaoqing,Yin Mingyue,Xue Huidong,Su Yu,Tian Songran

Niobium-doped MnO 2 /reduced graphene oxide (Nb-MnO 2 /RGO) composite has been successfully synthesized via a simple microwave radiation method. The samples were systematically studied by X-ray diffraction (XRD), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), and electrochemical measurements. As the anode material for lithium-ion batteries, the Nb-MnO 2 /RGO (molar ratio of Mn/Nb = 50:1) (NMG50) showed an outstanding reversible discharge capacity of 556.6 mAh g −1 after 50 cycles with a capacity retention of 77% at a charge-discharge rate of 0.1 A g −1 and the reversible discharge capacity can still retain 223.3 mAh g −1 at a current of 1 A g −1 , which is much higher than those for Nb-MnO 2 /RGO (molar ratio of Mn/Nb = 10:1) (NMG10) and undoped MnO 2 /RGO (MG). The improved electrochemical performance could be attributed to the proper amount of Nb doping, which could enhance both the conductivity and the structure stability of MnO 2 .

Enhanced Effect of Montmorillonite on Overall Properties of Polyimide-crown Ether Complex

Zheng Zhanping,Liu Shumei,Chen Zhigeng,Zhang Sen,Wirasaputra Alvianto,Zhao Jianqing

Organically modified montmorillonite (OMMT) was incorporated into the complex of 18-crown-6 (CE) and polyimide-croum ether (PI[CE]), and its effect on the properties of the complex was evaluated in terms of thermal behaviors, coefficient of thermal expansion, mechanical properties, dynamic mechanical properties and water absorption. The results indicate that the overall properties of PI[CE] complex are obviously enhanced. A very low coefficient of thermal expansion of 17.9 ppm/K, a high tensile strength of 124.5 MPa, and toughness of 30.8 MJ/m 3 can be achieved for the OMMT/PI[CE] nanocomposite with 3wt% OMMT. Meanwhile, the thermal stability of the PI[CE] complex is improved, and its 5% weight loss ( T d5% ) and T g increase by 10.6 and 23.0 °C, respectively, and the water absorption rate decreases from 1.73% to 1.13%. The homogeneous dispersion and strong interactions of OMMT with PI[CE] matrix are responsible for the superior properties of the nanocomposites according to SEM and XRD results.

Preparation of lignocellulose/graphene composite conductive paper

Wang Ruibin,Bian Huiyang,Ji Hairui,Yang Rendang

Practical production of conductive paper requires the balancing of high electrical conductance, thermal stability and tensile modulus, with cost effectiveness. By utilizing lignocellulose (3.85 ± 0.35% and 17.17 ± 0.62% lignin contents) and graphite as starting materials, a lignocellulose/reduced graphene oxide (LRGO) composite conductive paper is successfully fabricated. The free-standing LRGO paper has a low sheet resistance of 506 ± 34 Ω/sq with a graphene derivative content of ~ 20 wt%. Also high T onset (312 °C) and T 95 (251 °C) are observed, along with a tensile modulus up to 8.36 GPa if ten additional passes of microfluidization are used. Moreover, LRGO paper was used to make active electrodes for a supercapacitor that achieved a specific capacitance of 77.0 F/g. There has been minimal reporting of applying lignocellulose in conductive paper production, so this new method is anticipated to pave the way for developing advanced materials derived from low cost biomass. Graphical abstract