不同分子量PEO合成的聚乙二醇嵌段聚合物固体电解质研究

用不同平均分子量的聚乙二醇混合物和二氯甲烷在氢氧化钾存在下合成氧亚甲基连接的聚氧乙烯多嵌段聚合物作为电解质基质.通过正交实验,对影响凝胶型固体电解质室温电导率的因素,LiClO4、纳米SiO2、增塑剂碳酸乙烯酯、碳酸丙稀酯以及嵌段聚合物的用量等进行了优化研究和验证.实验结果表明,LiClO40.7g,SiO20.7g,嵌段聚合物为7g,EC/PC的质量比为5:0时,得到室温离子电导率为1.79×10-3S/cm的聚合物固体电解质.拉曼光谱分析表明体系中只有自由离子,没有发现离子对及离子聚集体.可见光透射光谱表明该体系可以用于制备电致变色器件、灵巧调光窗及新型平板显示器.     

PEO/PPC/Nano TiO_2-PMMA复合聚合物电解质膜的制备及性能

以聚甲基乙撑碳酸酯(PPC)和聚氧化乙烯(PEO)为基体材料,添加经聚甲基丙烯酸甲酯(PMMA)接枝改性的纳米TiO2(nano TiO2-PMMA),采用溶液浇铸法制备了锂离子电池PEO/PPC/TiO2-PMMA复合聚合物电解质(CPE)膜。用热重分析、红外光谱、交流阻抗、扫描电镜等方法研究了nano TiO2-PMMA对复合聚合物电解质膜的电化学性能影响。结果表明,当TiO2的接枝率为8.0%时,PEO/PPC/TiO2-PMMA复合聚合物电解质膜具有良好的电化学性能:室温离子电导率达到1.3×10-5 S/cm,电化学稳定窗口达到4.5V以上,锂离子迁移数为0.49。     

原位聚合制备P（AN-MMA）/TiO2复合聚合物电解质

以丙烯腈(AN)和甲基丙烯酸甲酯(MMA)为单体,在钛酸丁酯水解生成的TiO2粒子表面乳液聚合制备复合聚合物P(AN-MMA)/TiO2,并以此聚合物制备了多孔复合聚合物膜。采用核磁共振(NMR)、红外光谱(FT-IR)、差热分析(DSC)、扫描电镜(SEM)等对聚合物膜进行了表征,并测试了所得聚合物电解质的交流阻抗谱。结果表明,AN和MMA通过打开各自的C=C双键形成共聚物,TiO2在基体中分散均匀。当TiO2添加量为10.8%时,复合聚合物电解质的室温离子电导率达到1.12×10-3S/cm。     

锂盐对交联PPCMA聚合物电解质性能的影响

以二氧化碳(CO2)、环氧丙烷(PO)和马来酸酐(MA)三元共聚反应合成聚甲基乙撑碳酸酯马来酸酐(PPCMA),再经交联和浸渍电解液活化,制备了性能优良的PPCMA凝胶聚合物电解质。研究发现,随着交联剂过氧化二异丙苯(DCP)的增加,交联PPCMA的玻璃化转变温度升高,热稳定性增强,PPCMA凝胶聚合物电解质的离子电导率先增加后减小,当DCP用量为1.2%、LiClO4浓度为1.1mol/dm3、LiBOB质量分数为1.3%时,PPCMA凝胶聚合物电解质的室温离子电导率达到最大值1.47×10-2S/cm。Li/PPCMAGPE/LiNi1/3Co1/3Mn1/3O2聚合物锂离子电池的首次放电容量为115.3mAh/g。     

PEO/LiClO_4-(PC)_x-(SiO_2)_y电解质薄膜的制备及性能

以聚环氧乙烷(PEO)/高氯酸锂(LiClO_4)为基体材料,碳酸丙烯酯(PC)为增塑剂,正硅酸乙酯(TEOS)水解制得的纳米SiO_2为掺杂相,采用匀胶法制备了PEO/LiClO_4-(PC)_x-(SiO_2)_y电解质薄膜,考察了PC单掺和PC-SiO_2共掺对电解质薄膜微观形貌、电性能和物相结构的影响。结果表明,随着PC掺量的增加,室温下电解质薄膜离子电导率呈现先增加后减小的趋势,PEO/LiClO_4-(PC)0.4电解质薄膜的电导率达到极值6.26×10~(-6)S/cm,与未增塑PEO/LiClO_4薄膜相比提高了66%,表面平整度有所提高但仍存在少量波纹。PC与纳米SiO2共掺时制备的PEO/LiClO_4-(PC)0.4-(SiO_2)0.08电解质薄膜离子电导率达到最高值为1.55×10-5 S/cm,与PEO/LiClO_4-(PC)0.4电解质薄膜极值相比提高了1.5倍,薄膜表面平整。X射线衍射分析表明,PC和纳米SiO_2的加入大大降低了PEO的结晶度,有利于提高电解质薄膜的离子电导率。     

聚氧化乙烯-聚硅氧烷基离子液体复合聚合物电解质的研究

通过对不同聚硅氧烷(PDMS)含量的聚氧化乙烯-聚硅氧烷(PEO-PDMS)聚合物电解质电化学性能的测试,确定出PDMS最佳添加量,并以此聚合物配比为基体,通过复合不同质量分数的离子液体1-丁基-3-甲基咪唑双三氟甲磺酰亚胺盐([BMIM]TF-SI)或N-甲基、丙基哌啶双三氟甲磺酰亚胺盐(PP13TFSI),制备得到不同体系的离子液体复合聚合物电解质膜。离子液体的加入可显著提高聚合物电解质的室温电导率,样品PPP-100%室温电导率达到5.6×10-4S/cm。同时,样品均具有良好的热学和电化学稳定性。通过两种体系聚合物电解质性能对比得知,PP13TFSI离子液体复合聚合物电解质具有更优性能,有望作为新型电解质材料应用在锂离子电池中。     

聚磷腈纳米纤维掺杂聚氧化乙烯固态电解质制备与性能

通过原位模板诱导自组装法合成了聚磷腈纳米纤维(PPZF),将不同比例的聚磷腈纳米纤维掺杂到聚环氧乙烷(PEO)基质中制备得到固体聚合物电解质(SPE).研究结果表明,纳米纤维在电解质中形成一种3D网络导电通道,利于锂离子贯通迁移,从而提高电导率;含15 wt％PPZF的SPE室温离子电导率达2.21×10-5 S/cm...     

PVDF-HFP基聚合物电解质膜的制备及性能表征

采用相转化法制备了PVDF-HFP基多孔聚合物电解质,研究了PVDF-HFP的溶解温度、溶剂用量以及非溶剂用量等因素对聚合物电解质性能的影响,分别采用交流阻抗法和稳态电流法测定了聚合物电解质膜的离子电导率和离子迁移数,并通过扫描电镜观察了多孔聚合物膜的表面形貌.研究表明,制备PVDF-HFP多孔聚合物电解质膜的合适条件为:溶胶温度50~60℃、溶胶时间2 h、溶剂与PVDF的质量比为9~11、非溶剂与PVDF的质量比为0.5~0.25.该条件下制得的多孔聚合物电解质膜的孔隙率达到70%左右、离子迁移数在0.3左右、室温离子电导率达到1.6×10-3S.cm-1.     

基于季铵化壳聚糖-聚乙烯醇互穿网络型复合碱性聚电解质膜EI北大核心CSCD

通过对溶胶-凝胶法所制的纳米SiO_2进行季铵化改性得到季铵化SiO_2(QSiO_2),再将其与季铵化壳聚糖(QCS)和聚乙烯醇(PVA)的共混膜基体进行复合,经戊二醛交联制备了一系列不同QSiO_2添加量的互穿网络型QCS-PVA/QSiO_2复合碱性聚电解质膜。采用红外光谱、扫描电镜、热重分析、交流阻抗等考察了膜的结构、热稳定性和OH-离子电导率等。结果表明,无机粒子的加入使得复合膜的热稳定性提高,离子电导率呈现先上升后下降的趋势,在QSiO_2质量分数为5%时,其室温离子电导率达到最高0.0644 S/cm,是未添加QSiO_2的纯膜电导率(0.022 S/cm)近3倍,有望作为碱性聚电解质膜用于燃料电池中。     

纳米η-Al2O3双组元法合成Na-β″-Al2O3固体电解质

以纳米η-Al2 O3为原料,氧化镁(MgO)为稳定剂,采用双组元法制备Na-β″-Al2 O3固体电解质.通过Archimedes法,SEM和三点抗弯法研究试样的致密性、显微结构和力学性能;采用XRD和交流阻抗谱仪研究试样的β″-Al2 O3相含量和离子电导率.结果表明:双组元法有利于提高试样的结构均匀性;纳米η-Al2 O3比高纯α-Al2 O3更易于合成Na-β″-Al2 O3固体电解质;适量MgO的加入有利于提高试样中β″-Al2 O3相的含量和试样的致密性,减小试样的晶界电阻,提高试样的离子电导率;过多的Mg O掺杂量导致晶内气孔尺寸的长大,反而增大了试样的晶粒电阻,导致试样的离子电导率降低.当MgO的加入量为2％(质量分数)时,试样在300℃时的离子电导率最大,为0.0396 S·cm-1.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from