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1. chinaXiv:201705.00256 [pdf]

Excellent tribological and anti-corrosion performance of polyurethane composite coatings reinforced with functionalized graphene and graphene oxide nanosheets

Mo, MT [Mo, Mengting][ 1,2 ]; Zhao, WJ [Zhao, Wenjie][ 1 ]; Chen, ZF [Chen, Zifei][ 1,2 ]; Yu, QX [Yu, Quanyao][ 1,2 ]; Zeng, ZD [Zeng, Zhixiang][ 1 ]; Wu, XJ [Wu, Xuedong][ 1 ]; Xue, Q [Xue, Qunji][ 1 ]
分类: 材料科学 >> 材料科学(综合)

In order to improve the mechanical durability, polyurethane (PU) needs to be modified to enhance the tribological and anti-corrosion properties. In this work, we fabricated a series of PU composite coatings reinforced with functionalized graphene (FG) and functionalized graphene oxide (FGO). The structural and morphological features of the composite coatings were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The results showed that the dispersion and compatibility of graphene and graphene oxide were improved via chemical modification. Moreover, they effectively enhanced the tribological and anti-corrosion properties of PU composite coatings, whose optimized additive range was between 0.25 wt% and 0.5 wt%. The effect depends on the balance of lubrication and barrier of fillers and cracks generated by them. Finally, in comparison with FG/PU coatings, the FGO/PU coatings exhibited a better tribological property but worse anti-corrosion property owing to the abundant oxygenated groups of GO. They led to stronger interfacial interactions between FGO and the PU matrix, but destroyed the graphene lattice structure to some extent.

提交时间: 2017年05月09日 点击量:1042, 下载量:113

2. chinaXiv:201705.00229 [pdf]

Strong base pre-treatment for colorimetric sensor array detection and identification of N-methyl carbamate pesticides

Qian, SH [Qian, Sihua][ 1 ]; Leng, YM [Leng, Yumin][ 1,2 ]; Lin, HW [Lin, Hengwei][ 1 ]
分类: 材料科学 >> 材料科学(综合)

Colorimetric sensor arrays demonstrate numerous superior features in chemo- and bio-sensing, but they are generally not applicable to less-reactive analytes. Based on the findings that N-methyl carbamate pesticides could be decomposed into reactive phenols in basic media, herein, a novel strategy of strong base pre-treatment was developed and employed for the colorimetric sensor array detection and differentiation of the N-methyl carbamate pesticides in an indirect manner. With the use of five inexpensive and commercially available phenol responsive indicators, such a colorimetric sensor array can be facilely fabricated. Classification analysis (e.g. hierarchical clustering analysis (HCA) and principal component analysis (PCA)) reveals that the as-fabricated sensor array has an extremely high dimensionality and, consequently, exhibits excellence in discriminating a variety of N-methyl carbamates from other types of pesticides and potential interferants, and further identifying them exactly from each other. Moreover, semi-quantitative detection could also be achieved through combining HCA/PCA, recognition patterns, and corresponding fitting curves. Overall, the as-developed method exhibits high selectivity and sensitivity, good anti-interference, simultaneous detection and identification capability for each of the N-methyl carbamate pesticides, and potential applicability in real samples. Most importantly, this study demonstrates that pre-treatment strategies are very effective in expanding the range of applications of colorimetric sensor array methodology to less-reactive analytes.

提交时间: 2017年05月09日 点击量:1010, 下载量:121

3. chinaXiv:201705.00188 [pdf]

Magnetocaloric effect in high Gd content Gd-Fe-Al based amorphous/nanocrystalline systems with enhanced Curie temperature and refrigeration capacity

Zhang, LL [Zhang, Linlin][ 1,2 ]; Bao, MD [Bao, Mingdong][ 2 ]; Zheng, Q [Zheng, Qiang][ 2 ]; Tian, LH [Tian, Linhai][ 1 ]; Du, J [Du, Juan][ 3 ]
分类: 材料科学 >> 纳米科学和纳米技术

The Gd-Fe-Al amorphous/nanocrystalline composites were successfully designed and obtained with both high Curie temperature (Tc) and large magnetic entropy change (∆SM). The Tc can be tuned from 172 to 280 K and refrigeration capacity (RC) has a value between 690 and 867 J/kg under a eld change of 0–5 T by changing the Gd contents and the formation of Gd nanocrystallites. And, ∆SM in Gd-Fe-Al amorphous/nanocrystalline composites reached a value of 7.2 J kg−1 K−1 under a eld change of 0–5 T. The high RC in Gd-Fe-Al system were ascribed to the widening full width at half maximum (δFWHM) up to 240 K of the magnetic entropy change (∆SMmax) peak because of the combination contribution of amorphous matrix and the precipitated Gd-riched nanocrystalline. Our research would shed light on how to design attractive candidates for magnetic refrigeration materials with high perfor- manceatnearroomtemperature

提交时间: 2017年05月09日 点击量:193, 下载量:105

4. chinaXiv:201705.00218 [pdf]

Development of Energy Finite Element Analysis in Vibration Analysis of Composite Laminate Plate Structures

Yang, Y [Yang, Yang][ 1 ]; Chen, XL [Chen, Xiliang][ 1 ]; Zhang, WW [Zhang, Wenwu][ 1 ]
分类: 材料科学 >> 材料科学(综合)

The high frequency vibration analysis of a composite laminate plate structure subjected to impact loads was investigated by using method of energy finite element analysis (EFEA). The time and space averaged energy density was used as the primary variable to form the governing differential equations. The multilayer laminate plate is simplified to be equivalent isotropic plate using the average concept, such as the average damping loss factor and the average group speed. The global system of EFEA equations can be solved numerically and the energy density distribution within the whole system can then be obtained. The EFEA numerical results for composite laminate plate structure are validated through comparison with those of very dense conventional finite element analysis (FEA).

提交时间: 2017年05月09日 点击量:1067, 下载量:139

5. chinaXiv:201705.00216 [pdf]

Multi-responsive and tough hydrogels based on triblock copolymer micelles as multi-functional macro-crosslinkers

Sun, YN [Sun, Yuanna][ 1 ]; Liu, S [Liu, Shuang][ 1 ]; Du, GL [Du, Gaolai][ 1 ]; Gao, GR [Gao, Guorong][ 1 ]; Fu, J [Fu, Jun][ 1 ]
分类: 材料科学 >> 材料科学(综合)

Multi-stimuli responsive hydrogels are synthesized using self-assembled nanomicelles of Pluronic F127 diacrylate triblock copolymer as non- covalent macro-crosslinkers to in situ copolymerize with acrylamide and methyl chloride quaternized N,N-dimethylamino ethylacrylate mono- mers, generating positively charged hydrogels. These hydrogels showed high strength, toughness, and outstanding fatigue resistance, and are reversibly responsive to changes in pH and ionic strength.

提交时间: 2017年05月09日 点击量:1045, 下载量:123

6. chinaXiv:201705.00228 [pdf]

Polyacrylamide strengthened mixed-charge hydrogels and their applications in resistance to protein adsorption and algae attachment

Jiang, DY [Jiang, Daoyi][ 1 ]; Liu, ZX [Liu, Zhixiong][ 1 ]; He, XY [He, Xiaoyan][ 1 ]; Han, J [Han, Jin][ 1 ]; Wu, XD [Wu, Xuedong][ 1 ]
分类: 材料科学 >> 材料科学(综合)

Mixed-charge polymer hydrogels were successfully prepared by copolymerization of different ratios of [2-(meth-acryloyloxy) ethyl] trimethylammonium (TMA) and 3-sulfopropyl methacrylate (SA). Then, a second polyacrylamide (PAAM) network was incorporated into the pre-prepared hydrogel to form a double network (DN) hydrogel. The compositions of these DN hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Rheological and compressive measurements confirmed that the mechanical performances of the DN hydrogels were significantly improved by incorporation of a second PAAM network, compared with the according single network (SN) hydrogels. The amount of protein absorbed on the DN hydrogel surface was related to the ratio of TMA/SA and the ionic strength. The DN hydrogel with equal amount of TMA and SA exhibited better protein resistance. In addition, Phaeodactylum tricornutum and Chlorella were chosen for the anti-algae assay. The results displayed that the negatively charged hydrogels showed better anti-algae fouling performance than the positively charged and the neutral DN hydrogels. These DN hydrogels have promising applications in marine antifouling coating and interfaces of biomaterials.

提交时间: 2017年05月09日 点击量:1044, 下载量:129

7. chinaXiv:201705.00246 [pdf]

Edge-enriched porous graphene nanoribbons for high energy density supercapacitors

Zheng, C [Zheng, C.][ 1 ]; Zhou, XF [Zhou, X. F.][ 1 ]; Cao, HL [Cao, H. L.][ 1 ]; Wang, GH [Wang, G. H.][ 1 ]; Liu, ZP [Liu, Z. P.][ 1 ]
分类: 材料科学 >> 材料科学(综合)

A simple solution-based oxidative process and subsequent chemical activation combination method has been developed to prepare edge-enriched porous graphene nanoribbons (GNRs) as a high-performance electrode material for supercapacitors. The precursor aligned carbon nanotubes are cut longitudinally and unzipped by a modified Brodie method to form tube-like GNRs with abundant edges. The intermediate GNRs were subsequently chemically activated using KOH to generate a suitable porosity and create more edge sites. These edge sites contribute a larger capacitance than the basal plane of graphene and the nanopores facilitate the fast immigration of ions. As a result, the edge-enriched GNRs exhibit a capacitance uptake per specific surface area almost two times higher than that of conventional activated graphene sheets, which gives rise to the high energy density of the porous GNR electrode. The highly efficient utilization of the edge planes and easy, low-cost scale-up production will make porous GNRs potentially applicable to high-performance supercapacitors.

提交时间: 2017年05月09日 点击量:1023, 下载量:113

8. chinaXiv:201705.00240 [pdf]

A feasible multilayer structure design for solid lubricant coatings in a lunar environment

Pu, JB [Pu, Jibin][ 1 ]; Ren, SM [Ren, Siming][ 1 ]; Lu, ZB [Lu, Zhibin][ 2 ]; Wang, LP [Wang, Liping][ 1 ]
分类: 材料科学 >> 材料科学(综合)

Solid lubricant coatings have received considerable research attention in space applications owing to their remarkably improved tribological characteristics. But their service life is seriously restricted by the harsh environment, such as high vacuum and abrasive wear. In this paper, a novel design of carbon-based multilayer (MoS2/DLC multilayer) coatings was reported to clarify the friction and wear behavior in high vacuum conditions with and without simulated lunar-dust (SLD). Compared with pure DLC or MoS2 coatings, the multilayer coating showed excellent tribological performance with a low friction coefficient of 0.02 and a wear rate of $6.5 10 6 mm3 N 1 m 1. What is particularly interesting is that the wear volume of MoS2/DLC multilayer coatings with the increase of time is in accordance with the Archard linear law, regardless of the condition with or without SLD. Moreover, the surface morphology and composition of wear tracks and scars reveal that the long life of carbon-based multilayer coatings cannot be explained solely by excellent mechanical performance, and is also attributed to the formation of ridge layers as third body reservoirs and a tribo-induced composite transfer layer containing SLD nanoparticles and coating materials.

提交时间: 2017年05月09日 点击量:1021, 下载量:101

9. chinaXiv:201705.00245 [pdf]

Synthesis and characterization of novel 4-phenyl-pyridine unit based alkaline anion exchange membranes

Lu, D [Lu, Di][ 1,2 ]; Wen, LL [Wen, Lele][ 1,3 ]; Xue, LX [Xue, Lixin][ 1 ]
分类: 材料科学 >> 材料科学(综合)

For exploring more types of suitable polymeric membranes for application in alkaline fuel cells (AFCs), a series of 1,2-dimethylimidazolium functionalized poly(arylene ether sulfone)s containing 4-phenyl- pyridine units in the main chain (named as DIm-PPYPAES) were firstly synthesized as anion exchange membranes (AEMs) in this work. Proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize and confirm the chemical structure of the synthesized copolymers and the derived membranes. The DIm-PPYPAES membranes with different ionized levels ranging from 1.15 meq. g 1 to 1.77 meq. g 1, exhibited good thermal stability, solubility behavior and a relatively high level of hydroxide conductivity. The highest hydroxide conductivity of 83.35 mS cm 1 at 80 C was achieved for the DIm-PPYPAES-4 membrane with a moderate IEC of 1.77 meq. g 1. Moreover, after 15 days of treatment with a 2 M NaOH solution at 60 C, the DIm-PPYPAES membrane still exhibited relatively high ionic conductivity even above 10 mS cm 1 at 30 C and retained their integrated shapes.

提交时间: 2017年05月09日 点击量:1015, 下载量:112

10. chinaXiv:201705.00242 [pdf]

Improving thermal and mechanical properties of epoxy composites by using functionalized graphene

Pan, LL [Pan, Lulu][ 1 ]; Ban, JF [Ban, Jianfeng][ 3 ]; Lu, SR [Lu, Shaorong][ 1 ]; Chen, GX [Chen, Guoxin][ 2 ]; Yang, J [Yang, Jin][ 1 ]; Luo, QY [Luo, Qiyun][ 1 ]; Wu, LY [Wu, Linyan][ 1 ]; Yu, JH [Yu, Jinhong][ 1,2 ]
分类: 材料科学 >> 材料科学(综合)

Perylene tetracarboxylic anhydride (PTCDA) was reacted with 6-aminocaproic acid to form the corresponding perylene bisimide (PBI). PBI was used as the foundation for oligomerisation of glycidol in a ring-opening reaction of glycidol leading to a hyper branched, water-soluble glycidol derivative of perylene (PBI-HPG). PBI-HPG was bound to the reduced graphene oxide via p–p stacking resulting in a compound termed PBI-HPG/RGO. The structure and morphology of PBI-HPG/RGO were investigated by infrared spectroscopy (FT-IR), wide angle X-ray diffractometry (WAXD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). PBI- HPG/RGO was blended at different loadings in order to improve the thermal and mechanical properties of epoxy composites. The maximum Tg of the epoxy composites was about 20 C and the decomposition temperature (Td) was 26 C higher than that of neat epoxy. The incorporation of PBI- HPG/RGO yields a material with an impact strength of 39.6 kJ m 2 and a tensile strength at 0.7 wt%. It increased by 50.8% and 62.3%, respectively, compared to the neat epoxy.

提交时间: 2017年05月09日 点击量:1495, 下载量:460

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