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作者： Vogt, Bryan D. Qiang, Zhe Xue, Jiachen Deng, Guodong Karim, Alamgir Cavicchi, Kevin A. Department of Polymer Engineering University of Akron AkronOH44325 United States Material Science Engineering and Commercialization Program Texas State University San MarcosTX78666 United States

ISBN: (纸本)9780841229662

Cooperative assembly of block copolymers (BCPs) with carbonizable polymer precile route to nanoporous carbon materials with well-defined pore size and morphology. There is a subtle balance in reaction kinetics of the carbonizable precursor and ordering of the BCP that controls the extent and length scale over which the ordered structure persists. The use of low molecular weight precursors such as phenolic resin oligomers (resol) enable processing to further order and orient the ordered domains prior to "locking-in" the structure by thermally crosslinking the carbonizable precursor. Processing with solvent, either by exposure to their vapors or use of low volatility solvents in the casting solution, provides one low temperature route to markedly enhance order, but these nanostructures lack long-range orientation. Directional forces through application of a thermal gradient or shear enable large scale orientation of the nanostructures. © 2014 American Chemical Society.

关键词： Block copolymers

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The effect of mineral fillers on the rheological, mechanical and thermal properties of halogen-free flame-retardant polypropylene/expandable graphite compounds

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AIP Conference Proceedings 2015年第1期1664卷

作者： Hannelore Mattausch Stephan Laske Dieter Hohenwarter Clemens Holzer aChair of Polymer Processing Department of Polymer Engineering and Science Montanuniversitaet Leoben Otto-Gloeckel-Strasse 2 8700 Leoben Austria bFederal Institute of Technology Plastics Technology and Environmental Engineering TGM Vienna Wexstrasse 19-23 1200 Vienna Austria

In many polyolefin applications, such as electrical cables or automotive applications, the fire protection is a very important task. Unfortunately flame-retardant polymeric materials are often halogenated and form toxic substances in case of fire, which explains the general requirement to reduce the halogen content to zero. Non-halogenated, state-of-the-art flame retardants must be incorporated into the polymer in very high grades (> 40 wt%) leading to massive decrease in mechanical properties and/or processability. In this research work halogen-free flame-retardant polypropylene (PP) /expandable graphite (EG) were filled with minerals fillers such as layered silicates (MMT), magnesium hydroxide (MgOH), zeolite (Z) and expanded perlite (EP) in order to enhance the flame-retardant effect. The rheological, mechanical and thermal properties of these materials were investigated to gain more fundamental knowledge about synergistic combinations of flame-retardants and other additives. The rheological properties were characterized with a rotational rheometer with plate-plate setup. The EG/EP/PP compound exhibited the highest increase in viscosity (∼ 37 %). As representative value for the mechanical properties the Young’s modulus was chosen. The final Young’s modulus values of the twofold systems gained higher values than the single ones. Thermo gravimetric analysis (TGA) was utilized to investigate the material with respect to volatile substances and combustion behavior. All materials decomposed in one-step degradation. The EG filled compounds showed a significant increase in sample weight due to the expansion of EG. The combustion behavior of these materials was characterized by cone calorimeter tests. Especially combinations of expandable graphite with mineral fillers exhibit a reduction of the peak heat release rate during cone calorimeter measurements of up to 87% compared to pure PP.

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Centrifugal Spinning: An Alternative Approach to Produce Nanofibers at High Speed and Low Cost

Centrifugal Spinning: An Alternative Approach to Produce Nan...

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The 89th Textile Institute World Conference(第89届世界纺织大会)

作者： Yao Lu Xiangwu Zhang Fiber and Polymer Science Program Department of Textiles EngineeringChemistry and ScienceNorth Carolina State University

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Centrifugally-spun nanofibers for advanced energy storage

Centrifugally-spun nanofibers for advanced energy storage

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2014国际纳米技术和新能源材料研讨会——暨世界著名科学家来鄂讲学计划武汉论坛

作者： Xiangwu Zhang Fiber and Polymer Science Program Department of Textile EngineeringChemistry and ScienceNorth Carolina State University

Among the various existing energy storage technologies, rechargeable lithium-ion batteries and supercapacitors have been considered as two important solutions to the increasing needs for high-performance electrochemical power sources. N ovel centrifugally-spun nanofibers with functional properties can dramatically alter surface reaction rates and charge transport throughout the batteries and supercapacitors,

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Lithium-Ion Batteries: Excimer Ultraviolet-Irradiated Carbon Nanofibers as Advanced Anodes for Long Cycle Life Lithium-Ion Batteries (Small 38/2016)

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Small 2016年第38期12卷

作者： Zhen Shen Yi Hu Yanli Chen Renzhong Chen Xia He Lei Geng Xiangwu Zhang Keshi Wu Key Laboratory of Advanced Textile Materials and Manufacturing Technology Ministry of Education Zhejiang Sci-Tech University Hangzhou 310018 P. R. China Engineering Research Center for Eco-Dying & Finishing of Textiles Ministry of Education Zhejiang Sci-Tech University Hangzhou 310018 P. R. China Dyeing and Finishing Institute of Zhejiang Sci-Tech University Zhejiang Sci-Tech University Hangzhou 310018 P. R. China Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC 27695–8301 USA

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Surface modification of halloysite for epoxy nanocomposite applications 72

Surface modification of halloysite for epoxy nanocomposite a...

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72nd Annual Technical Conference of the Society of Plastics Engineers: The Plastics Conference, ANTEC 2014

作者： Zeng, Songshan Reyes, Christopher Rodgers, Paul Wentworth, Samuel Sun, Luyi Department of Chemical and Biomolecular Engineering and Polymer Program Institute of Materials Science University of Connecticut StorrsCT06269 United States Department of Chemistry and Biochemistry Texas State University San MarcosTX78666-4684 United States

ISBN: (纸本)9781634397087

polymer nanocomposites have been extensively investigated over the past two decades, resulting in a wide range of applications because of their excellent performance. Halloysite, a type of naturally occurring aluminosilicate, has attracted increasing interest in polymer nanocomposite applications, especially for the enhancement of mechanical properties owing the tubular structure of halloysite. Herein, we report a facile approach to achieve a high level of dispersion of halloysite nanotubes (HNTs) in epoxy by treating HNTs with a low concentration (0.015mol/L) of sodium hydroxide (NaOH). The NaOH treatment resulted in the formation of hydroxyl groups on the surface of HNTs, leading to a better dispersion of HNTs in polar solvent and epoxy matrix, which was verified by the Zeta potential characterization. Such a higher level of dispersion and strong interface helped enhance the modulus and fracture toughness of epoxy/HNT ( 5 phr HNT) by and 18% and 43%, respectively, in comparison to the neat epoxy. The dynamic mechanical analysis (DMA) revealed a 13% increment in the storage modulus of the composite at 50 °C. The SEM images of the fractured surfaces further confirmed the better dispersion of treated HNTs in the epoxy matrix, as opposed to the large agglomeration of untreated HNTs in the epoxy nanocomposite. Copyright © (2014) by the Society of Plastics Engineers All rights reserved.

关键词： Nanocomposites

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Precursors in stereo-complex crystals of poly(l-lactic acid)/poly(d-lactic acid) blends under shear flow

Precursors in stereo-complex crystals of poly(l-lactic acid)...

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作者： Hemmi, Kota Matsuba, Go Tsuji, Hideto Kawai, Takahiko Kanaya, Toshiji Toyohara, Kiyotsuna Oda, Akimichi Endou, Kou Department of Polymer Science and Engineering Yamagata University 4-3-16 Jonan Yonezawa Yamagata 992-8510 Japan Department of Environmental and Life Sciences Toyohashi University of Technology Toyohashi Aichi 441-8580 Japan Division of Production Science and Technology Gunma University Ota Gunma 373-0057 Japan Institute for Chemical Research Kyoto University Uji Kyoto-fu 611-0011 Japan Teijin Limited Iwakuni Yamaguchi 740-8511 Japan

To improve the mechanical and the thermal performance of poly(lactic acid) materials, this work focuses on the formation of stereo-complex crystals by blending poly(l-lactic acid) (PLLA) with poly(d-lactic acid) (PDLA). The resulting structure was analyzed using time-resolved in situ X-ray scattering, optical microscopy, differential scanning calorimetry and viscoelastic measurements. The objective of this study is to investigate the effect of shear flow imposed prior to crystallization on higher-order structure formation and acceleration of stereo-complex crystal growth of PLLA and PDLA blends using a wide spatial scale analysis and viscoelastic measurements. Density fluctuations of 100 nm scale were observed prior to nucleation by in situ simultaneous wide- and small-angle X-ray scattering measurements. These density fluctuations grew with time and the intensity increased with increasing shear rate. Furthermore, the results revealed that the PLLA and PDLA chains were only partially interpenetrated;consequently, stereo-complex crystals could grow only in the mixed PLLA/PDLA phase. The correlation length of density fluctuation prior to nucleation was strongly dependent on the mixed phases. © 2014 International Union of Crystallography.

关键词： Shear flow

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Mathematical Model and Fabrication of Multi-Layer Electrochemical Glucose Sensors

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International Journal of High Speed Electronics and Systems 2015年第3N04期24卷

作者： Robert A. Croce, Jr. Santhisagar Vaddiraju Allen Legassey Fotios Papadimitrakopoulos Faquir C. Jain Biorasis Inc. 1392 Storrs Road Storrs CT 06269 USA Department of Electrical & Computer Engineering University of Connecticut Storrs CT 06269 USA Nanomaterials Optoelectronics Laboratory Polymer Program Institute of Materials Science University of Connecticut Storrs CT 06269 USA Department of Chemistry University of Connecticut Storrs CT 06269 USA

The design and fabrication of multi-layer amperometric electrochemical glucose sensors is dependent upon the diffusional kinetics of the chemical/biochemical species which contribute to the sensor’s response. Considerable effort has been carried out to coat the working electrode with appropriate glucose flux-limiting membranes which is pertinent for superior in vivo performance, and hence requires a careful understanding of the participating species within the sensor cross-sectional architecture. This contribution reports the computational modeling of Clark’s first generation amperometric glucose sensor coated with an electro-polymerized glucose oxidase (GOx) layer along with a layer of polyurethane (PU) employed to reduce the glucose-influx in order to generate linear operation over the normal physiological glucose range in vivo . The model was programmed using MATLAB and utilizes the finite-difference method for the solution to the enzymatic reaction-based diffusion equations. Additionally, experimental devices were fabricated, tested and compared with the simulated results. The simulation of these devices have been shown to align well with experimentally fabricated devices in terms of amperometric current density. The increase in device linearity with the addition of the outer glucose-flux limiting PU membrane corroborate our experimental findings reported in this study which can be used as a powerful analytical tool in designing high–performance next generation implantable glucose sensors.

关键词： Finite difference computations numerical modeling differential equations glucose sensors

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Influence of electron beam treatment of jute on the thermal properties of random and two-directional jute/poly(lactic acid) green composites

Influence of electron beam treatment of jute on the thermal ...

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作者： Ji, Sang Gyu Hwang, Jeong Hyun Cho, Donghwan Kim, Hyun-Joong Department of Polymer Science and Engineering Polymer/Bio-Composites Research Lab Kumoh National Institute of Technology Gumi Gyeongbuk 730-701 Korea Republic of Program in Environmental Materials Science Seoul National University Seoul 151-921 Korea Republic of

In the present study, randomly aligned jute fiber/poly(lactic acid) (PLA) and two-directionally aligned jute fabric/PLA green composites with jute (50% by weight) treated with electron beam at different dosages (0, 5, 10, 30, 50, and 100 kGy) were fabricated by compression molding technique and the effect of electron beam treatment on their thermal properties was investigated in terms of thermal expansion, thermal stability, dynamic mechanical thermal property, and heat deflection temperature (HDT). The dynamic storage modulus and HDT of neat PLA were significantly increased by incorporating jute fibers or fabrics into PLA, whereas the coefficient of thermal expansion (CTE) and the damping property were decreased, reflecting the enhancement in the interfacial adhesion between the jute and the PLA by electron beam treatment with an optimal dosage of 10 kGy and the reinforcing effect by jute. The result exhibited that the thermal stability, storage modulus, and HDT of jute/PLA green composites were highest with the electron beam irradiation of jute at 10 kGy and lowest at 100 kGy, whereas the CTE and tan δ were lowest at 10 kGy and highest at 100 kGy. The thermal behavior of random jute/PLA green composites shows a similar tendency to that of 2D jute/PLA counterparts and the influence of electron beam irradiation on the thermal properties studied was consistent with each other. The thermomechanical analysis, dynamic mechanical thermal analysis, thermogravimetric analysis, and HDT results were in agreement with each other, showing a comparable effect of electron beam irradiation on composites thermal characteristics. © 2013 Taylor & Francis Group, LLC.

关键词： Irradiation

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Co3O4/carbon composite nanofibers for use as anode material in advanced lithium-ion batteries

Co3O4/carbon composite nanofibers for use as anode material ...

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作者： Li, Shuli Fu, Kun Xue, Leigang Toprakci, Ozan Li, Ying Zhang, Shu Xu, Guanjie Lu, Yao Zhang, Xiangwu Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC 27695-8301 United States

ISBN: (纸本)9780841228139

Co3O4/carbon composite nanofibers were prepared by a combination of electrospinning and carbonization methods using 10 - 30 nm and 30 - 50 nm Co3O4 nanoparticles, respectively, and their potential use as the anode material in rechargeable lithium-ion batteries was investigated. The composite Co3O4/carbon nanofiber electrode containing 30 - 50 nm Co3O4 nanoparticles showed large reversible capacities and good cycleability with charge capacities of 677 and 545 mAh g-1 at the second and twentieth cycles, respectively. In contrast, the composite Co3O4/carbon nanofiber electrode containing 10 - 30 nm Co3O4 nanoparticles showed fast capacity fading during cycling due to severe nanoparticle aggregation. Results suggested that the good electrochemical performance of Co3O4/carbon nanofiber electrode containing 30 - 50 nm Co3O4 nanoparticles was ascribed to the combination of the properties of both Co 3O4 nanoparticles (large Li storage capability) and carbon nanofiber matrix (long cycle life), and therefore this electrode material could be potentially used in high-energy rechargeable lithium-ion batteries. © 2013 American Chemical Society.

关键词： Lithium-ion batteries

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