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Poly(vinylidene fluoride) reinforced by carbon fibers: structural parameters of fibers and fiber-polymer adhesion

APPLIED SURFACE SCIENCE 2012年第24期258卷 9570-9578页

作者： Wang, Jianghong Wu, Defeng Li, Xiang Zhang, Ming Zhou, Weidong Yangzhou Univ Sch Chem & Chem Engn Yangzhou 225002 Jiangsu Peoples R China Yangzhou Univ Testing Ctr Yangzhou 225002 Jiangsu Peoples R China

Poly(vinylidene fluoride) (PVDF) composites containing carbon fibers (CFs) with or without surface treatment were prepared via melt mixing. The mechanical properties of the PVDF/CF composites were then studied to explore the relations between the short-range and long-range structures of CFs and the properties of the composites. The results showed that the presence of CFs had a reinforcement effect on the PVDF and the Nielsen model was used to describe the concentration effect of CFs, especially at the lower concentration levels. The short-range aspect ratio structure and the long-range orientation structure of the CFs are the two most important structures that affected the final properties of the composites. The effective aspect ratio and orientation degree of the CFs in the PVDF matrix can be evaluated by the Halpin-Tsai and the Krenchel-COX models, which agree well with the experimental observations. After surface treatment, the CFs show stronger reinforcement effect due to reduced interfacial tension and increased interfacial area between two phases (C) 2012 Elsevier B. V. All rights reserved.

关键词： Poly(vinylidene fluoride) Carbon fiber Composites structural parameters Interfacial tension

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Effect of structural parameters on the torsional behavior of C/SiC pipe

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CERAMICS INTERNATIONAL 2017年第17期43卷 15828-15833页

作者： Li, Min Xu, Zhenye Mei, Hui Chongqing Radio & TV Univ Coll Elect Informat Engn Chongqing 400052 Peoples R China Northwestern Polytech Univ Sci & Technol Thermostruct Composite Mat Lab Xian 710072 Shaanxi Peoples R China

Based on the principles of classical laminate theory, the 3D finite element analysis model of C/SiC pipe has been established by using finite element analysis software ABAQUS. Tsai-Hill failure criterion was applied to identify the critical areas of failure in composite laminates. Through the finite element simulation, the torsional properties of C/SiC pipe under different length, internal diameters and wall thickness were studied. The simulation results show that with the increase of the pipe length, the angle of twist per unit length decreased. With the increase of internal diameters of the pipe, the anti-torsion performance of the pipe increases gradually, and the angle of twist per unit length gradually decreases until it remains the same, and the wall thickness of the pipe have little effect on the torsional performance. The experimental results show that the simulated torsional properties are in good agreement with the experimental results.

关键词： C/SiC structural parameters Torsional properties Finite element analysis (FEA)

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Conformational stability of CH₃CH₂PH₂BH₃ from temperature dependent FT-IR spectra of xenon solutions and r₀ structural parameters

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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000年第1期56卷 29-46页

作者： Durig, JR Robb, JB Xiao, JP Gounev, TK Univ Missouri Dept Chem Kansas City MO 64110 USA

Variable temperature ( - 55- - 100 degrees C) studies of the infrared spectra (3500-400 cm(-1)) of ethylphosphine-borane, CH3CH2PH2BH3, and ethylphosphine-borane-d(5) dissolved in liquid xenon have been recorded. From these data, the enthalpy difference has been determined to be 86 +/- 8 cm(-1) (1.03 +/- 0.10 kJ/mol), with the trans conformer the more stable rotamer. Complete vibrational assignments are presented for both conformers, which are consistent with the predicted frequencies obtained from the ab initio MP2/6-31G(d) calculations. The optimized geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, and depolarization ratios have been obtained from RHF/6-31G(d) and/or MP2/6-31G(d) ab initio calculations. These quantities are compared to the corresponding experimental quantities when appropriate as well as with some corresponding results for some similar molecules. The r(o) structural parameters have been obtained from a combination of the previously reported microwave rotational constants and ab initio predicted parameters. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： conformational stability FT-IR spectra xenon solutions structural parameters

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Dilution method study on the interfacial composition and structural parameters of water/C₁₂-EO_x-C_12•2Br/n-hexanol/n-heptane microemulsions:: Effect of the oxyethylene groups in the spacer

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2007年第1期310卷 331-336页

作者： Zheng, Ou Zhao, Jian-Xi Yan, Hua Gao, Shao-Kang Fuzhou Univ Coll Chem & Chem Engn Dept Appl Chem Fujian 350002 Peoples R China

The interfacial composition and the structure of the water/C-12-EOx-C-12.2Br/n-hexanol/n-heptane microemulsion have been investigated by the dilution method. The results showed that C-12-EOx-C-12.2Br formed a stable water/oil microemulsion with the assistance of n-hexanol. Owing to the relatively large size of the head group, more n-hexanol molecules are populated on the droplet surface than in the C-12-2-C-12. 2Br system. The radius of the water pool of the C-12-EO3-C-12.2Br system is not as sensitive to W-o as in the C-12-2-C-12.2Br system. Another feature of the present system is that its droplet size is considerably smaller than that of the C-12-2-C-12.2Br system, and also those of the CPC and CTAB systems at relative high water content. This provides a potential application for the synthesis of nanoparticles with small size. (c) 2007 Elsevier Inc. All rights reserved.

关键词： C-12-EOx-C-12 center dot 2Br homologs n-hexanol dilution method interfacial composition of the w/o microemulsion structural parameters

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Local fouling characteristics of CaCO3 in corrugated tubes with different structural parameters

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INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER 2024年 156卷

作者： Han, Zhimin Zhang, Hongyu Wang, Chang Zhou, Xiangyu Northeast Elect Power Univ Sch Energy & Power Engn Jilin Jilin Peoples R China

Enhanced tubes are characterized by better heat transfer efficiency compared to circular tubes and are widely used in heat transfer applications. However, owing to the complex structural characteristics of these tubes, local fouling can occur in some parts of the pipeline. In some serious cases,this may lead to bursting of the tube. To address the local fouling problem of enhanced tubes, this study considers corrugated tubes as the research object. Herein, a numerical simulation approach was adopted to study the local fouling deposition under different structural parameters of corrugated tubes. The fouling deposition under different corrugation heights, widths, and spacings of the corrugated tubes was systematically analyzed. The results showed that corrugated tubes yielded a better fouling suppression effect than circular tubes. In this regard, the local fouling resistance (average) of the corrugated tube is 27% lower than that of the circular tube. Furthermore, the distribution of the corrugated tube local fouling resistance along the length of the pipe was found to be periodic. Different fouling extremes were reported in one cycle. The maximum value was obtained in the front part of the tapering section of the corrugated tubes, and the minimum value was experienced in the middle of the tapering section. Moreover, the local fouling resistance value decreased with an increase in the corrugation height and increased with an increase in the corrugation width or spacing. Overall, this study shows that the corrugation height exhibits a greater fouling inhibition effect on the corrugated tubes compared to the corrugation width and spacing.

关键词： Corrugated tubes structural parameters Fouling model Local fouling resistance Numerical simulation

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Detonation temperature of high explosives from structural parameters

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JOURNAL OF HAZARDOUS MATERIALS 2006年第3期137卷 1303-1308页

作者： Keshavarz, Mohammad Hossein Malek Ashtar Univ Technol Dept Chem Shahin Shahr Iran

A new scheme is introduced for calculating detonation temperature of different classes of high explosives. The ratio of oxygen to carbon and hydrogen to oxygen as well as specific structural parameters are the fundamental factors in the new method. An empirical new correlation is used to calculate detonation temperature of energetic compounds without considering heat contents of explosives and detonation products. Calculated detonation temperatures for both pure and explosive formulations show good agreement with respect to measured detonation temperatures and complicated computer code using BKWR and BKWS equations of state. Predicted detonation temperatures have root-mean-square (rms) percent deviation of 4.6, 14.2 and 4.6 from measured values for new method, BKWR and BKWS equations of state, respectively. (c) 2006 Elsevier B.V. All rights reserved.

关键词： detonation temperature structural parameters correlation elemental composition

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The effect of structural parameters on the tribological properties of structural-coupling self-lubricating coatings

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SURFACE & COATINGS TECHNOLOGY 2020年 403卷

作者： Zhao, Hang Liu, Yu-feng Wu, Xiao-yu Gao, Chang Zhu, Li-kuan Xu, Bin Shenzhen Univ Coll Mechatron & Control Engn Guangdong Prov Key Lab Micro Nano Optomechatron E Shenzhen 518060 Peoples R China

In this paper, a Cu-C/HDS structural-coupling self-lubricating coating (SSC) was successfully prepared on an H13 hot-work die steel (HDS) by wire electrical discharge machining and vacuum pressure thermal-diffusion welding. The effect of structural parameters as well as microstructure, composition and microhardness on the tribological properties of the SSC was investigated in detail. In the SSC, the self-lubricating units (SUs) distribute alternately with the HDS units (HDSUs) to form a striped coupling structure. The HDSUs have a microstructure consisting of gamma-Fe, martensite, (Fe, Cr, V) and Cr-rich carbides, and the SUs consist primarily of the Cu-matrix and graphite. Distinctive microstructures determine that the hardness of the HDSUs is much higher than that of the SUs. As a result, microhardness with alternating softness and hardness occurs on the surface of the SSC. The tribological properties of the SSCs were evaluated through the reciprocating friction and wear test and compared with the HDS substrate and the Cu-C coating at room temperature. The results show that the SSCs exhibit considerably better antifriction properties compared to the HDS substrate. Even some samples are better than the pure Cu-C coating. This result is attributed mainly to the positive role of the SUs and the synergistic effect between the coupling units. The tribological properties of SSCs have a close relationship with the fill ratio and the width ratio. With the increase in the fill ratio and the width ratio, the friction coefficient of the SSC first decreases and then increases slightly, while the wear rate presents mainly an overall upward trend. It mainly involves the supply of lubricants and the wear dominance of the SUs. Moreover, when the self-lubrication property of the SSC is determined by the fill ratio or the width ratio, choosing a smaller width for the SU is beneficial to improve the wear resistance.

关键词： Self-lubricating coating Tribological properties structural parameters Composites

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Study on the thiophosphinic extractants. II. Thermodynamic functions and structural parameters of the w/o microemulsion of the saponified acid systems

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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 2002年第2-3期211卷 249-258页

作者： Fu, X Xiong, YH Wei, QL Xue, SY Zhang, SO Hu, ZS Qingdao Univ Sci & Technol Qingdao 266042 Peoples R China Qingdao Univ Normal Inst Qingdao 266071 Peoples R China

Purified sodium salt of Cyanex302, di (2,4,4-trimethylpentyl) monothiophosphinic sodium, NaDTMPTP, and that of Cyanex301, di (2,4,4-trimethylpentyl) dithiophosphinic sodium, NaDTMPDTP, are prepared from the corresponding extractant respectively. The thermodynamic function DeltaG(0-->i)(0) (standard Gibbs free energy change of transferring alcohol from oil phase to interface phase) and structural parameters of the sodium salt NaA (0.200 g)-alcohol-diluent-H2O microemulsion system are measured. The effects of substitution of oxygen by sulfur in the extractant molecule, the used diluent, alcohol, the temperature and water content V-H2O on the thermodynamic function and structural parameters are discussed and compared with the corresponding sodium salt of phosphinic acid (purified Cyanex272) system, respectively. The replacement of oxygen atom(s) by sulfur in HA or NaA molecules makes their steric configurations and polarities changed. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： cyanex302 cyanex301 cyanex272 thermodynamic function structural parameters water-in-oil microemulsion

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Influence of structural parameters and transition interface on the fracture property of Al₂O₃/Mo laminated composites

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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 2015年第5期35卷 1581-1591页

作者： Song, Junjie Zhang, Yongsheng Fang, Yuan Fan, Hengzhong Hu, Litian Qu, Jianmin Chinese Acad Sci Lanzhou Inst Chem Phys Lanzhou 730000 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Northwestern Univ Evanston IL 60201 USA

This paper proposes a set of new structural parameters to quantify the fracture behavior of Al2O3/Mo laminated composites. The relationships between the relevant structural parameters and mechanical properties of the materials were analyzed. Results show that the variation of structural parameters causes significant changes in the effective proportion of Mo phase and the contribution to the crack propagation energy of the materials, thus realizing the optimization of the materials. Based on these analyses, we formulated a set of principles and theoretical models to design Al2O3/Mo laminated composites. Furthermore, the performance of the Al2O3/Mo laminated composites can be improved further by introducing a transition interface with appropriate Mo content. We demonstrated that the toughness and work of fracture of Al2O3/Mo laminated composites could reach 7.3 MPa M-1/2 and 8757 J m(-2), respectively. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Layered structures Alumina (alpha-Al2O3) structural parameters Transition interface Fracture

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INFLUENCE OF structural parameters OF INTERMITTENT DISCHARGE EQUIPMENT ON HOLE FERTILIZATION PERFORMANCE

JOURNAL OF THE ASABE

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JOURNAL OF THE ASABE 2022年第2期65卷 357-366页

作者： Zhang, Kang Wu, Xue Mei Song, Zhu Jun Zhang, Fu Gui Zhen, Le Guizhou Univ Sch Mech Engn Guiyang Peoples R China

Fertilizers are necessary for high crop yields. In mechanized application of starter fertilizer for tobacco, discharging the fertilizer immediately below the seedlings promotes root growth and nutrient uptake, resulting in a high utilization rate. This placement is called hole fertilizer application and is fertilizer-saving and environment-friendly. To meet the requirements of hole fertilizer application for crops with specific plant spacing, equipment to intermittently discharge fertilizer has been designed based on the structure of a fluted roller. To explore the influence of the structural and working parameters of the intermittent discharge equipment on the uniformity of hole fertilization and the accuracy of marking fertilizer positions, the fertilizer discharge process and marking process were simulated using a discrete element method based on theoretical analysis. The optimal combination of parameters was a tapered circular groove shape with three grooves, the rotational speed of the fluted roller was 30 rpm, and the center distance between two material bins was 40 cm. In the simulation, the coefficient of variation for single-hole fertilizer application was 3.39%, and the marking error was 1.86 cm. Bench tests were performed using the optimal combination of parameters to verify the simulation results. The intermittent discharge equipment was able to achieve hole fertilizer application and mark the fertilizer position. The coefficient of variation for single-hole fertilizer application was 4.35%, and the marking error was 1.95 cm. The bench tests proved that the discrete element method was feasible for optimizing the equipment parameters. This study provides a reference for developing hole fertilizer application equipment and control systems to improve fertilizer use efficiency.

关键词： Fertilizer performance Groove structure Hole fertilizer application Intermittent fertilizer discharge structural parameters

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