原位合成法制备磷钨酸掺杂的聚乙烯醇/聚偏氟乙烯质子交换膜及其在直接甲醇燃料电池中的应用

将磷酸和钨酸钠溶于聚乙烯醇(PVA)和聚偏氟乙烯(PVDF)的二甲基亚砜极性有机溶液中,利用原位合成法制备了膜中分布均匀的磷钨酸掺杂的聚乙烯醇/聚偏氟乙烯质子交换膜(PWA-d-PVA/PVDF)。应用多功能材料实验机表征了膜的力学强度,使用交流阻抗谱和气相色谱仪研究了PVDF含量对PWA-d-PVA/PVDF膜的质子导电、溶胀和阻醇等性能的影响。同时通过热重和电镜扫描等方法对膜的热稳定性和形貌进行了表征。结果表明,膜中PVDF含量增大,膜的溶胀度降低,热稳定性提高,强度增大。与Nafion膜的性能相比,PVDF质量分数为20%的PWA-d-PVA/PVDF膜的溶胀度降低了23.8%,甲醇渗透率降低了1个数量级。PWA-d-PVA/PVDF(20%)膜在甲醇浓度为2mol/L时的直接甲醇燃料电池(DMFC)中测得最大功率密度为15.08mW/cm2。     

PAMPS/PVA复合质子交换膜的电导率及阻醇性能

制备了聚2-丙烯酰胺-2-甲基丙磺酸(PAM PS)/聚乙烯醇(PVA)复合质子交换膜,并研究了膜的组成、甲醇水溶液浓度等对膜力学强度、电导率和甲醇渗透率的影响。实验发现,当PAM PS含量为50%时,此复合膜拉伸强度可达21.8 M Pa,电导率σ可达1.5×1-0 2S/cm,并且甲醇透过率P仅为9.8×1-0 8cm2/S。     

磷钨酸掺杂PVA/纳米SiO2复合膜甲醇渗透及质子导电性能的研究

研究了磷钨酸( PWA)掺杂聚乙烯醇(PVA)/纳米二氧化硅(nano SiO2)复合质子导电材料的甲醇渗透性能和质子导电性能。研究结果表明,有机无机纳米复合膜的甲醇阻隔性能随着SiO2 的加入而提高,随着PWA的加入而降低,复合膜和PVA的甲醇渗透率随甲醇浓度的增大而降低。随着温度的升高复合膜的质子导电率也相应增加,复合膜的常温质子导电率可达10-5S·cm-1。质子导电率与温度的关系不符合Arrhenius关系,可用WLF方程或VTF方程来拟合,这种复合膜的质子输送过程主要与聚合物链运动有关。纳米SiO2 的加入有利于提高复合膜在较高温度时的水保留能力,70℃时复合膜的吸水率是纯PVA吸水率的4 倍,使得复合膜可以在较高温度下使用。     

聚偏氟乙烯-磺化聚苯乙烯质子交换膜的制备与表征

采用热诱导溶液聚合和相转移技术,制备了新型聚偏氟乙烯-磺化聚苯乙烯(PVDF-SPS)质子交换膜。采用X射线衍射光电子能谱(XPS)、环境扫描电镜(ESEM)和红外光谱(FT-IR)对PVDF-SPS质子交换膜进行了表征,研究了质子膜的吸水率、质子传导率和甲醇渗透系数。结果表明,PVDF-SPS质子膜具有优良的亲水性能,较高的质子传导率和较低的甲醇渗透系数。PVDF-SPS质子交换膜在25℃的质子传导率和甲醇渗透系数分别为2.93×10-2S/cm和8.61×10-8cm2/s,其质子传导率与甲醇渗透系数比值为3.40×105S.s/cm3,超过Nafion-117膜的20倍。     

季铵化壳聚糖-聚乙烯醇阴离子交换膜的性能

碱性直接甲醇燃料电池(ADMFC)具有电极反应速率高,甲醇渗透率低的优点,阴离子交换膜是ADMFC的核心之一.以壳聚糖(CS)和环氧丙基三甲基氯化铵为原料合成季铵化壳聚糖,将其与聚乙烯醇(PVA)共混后制得一系列不同配比的季铵化壳聚糖(QCS)/聚乙烯醇阴离子交换膜,对膜的导电率和甲醇渗透系数进行了测试和分析.结果表明:季铵化壳聚糖与聚乙烯醇有较好的相容性,所制季铵化壳聚糖(QCS)/聚乙烯醇共混膜结构致密均匀,膜的吸水率和溶胀度随季铵化壳聚糖含量增大而减小,离子导电率随季铵化壳聚糖含量增大而提高,80℃时季铵化壳聚糖含量为60%的共混膜导电率最高可达2.5×10-2 S/cm.膜的甲醇渗透系数低于Nafion膜.     

磺化聚酰亚胺/SiO2复合膜的制备及其质子交换性能研究

制备了具有不同硅含量的磺化聚酰亚胺/二氧化硅(SPI/SiO2)复合膜,研究了SiO2的引入对复合膜的力学性能、耐热性能、尺寸稳定性以及抗氧化和耐水解稳定性的影响规律,并对其质子传导率和甲醇渗透率进行了评价。结果表明,与商业化的Nafion115膜相比,复合膜表现出更优异的阻醇特性和选择透过性,其中SPI/SiO2-2复合膜具有更突出的高温质子传导特性。     

PVA/FA/H-ZSM-11复合质子交换膜的制备及性能研究

以聚乙烯醇(PVA)为基材,掺杂一定量的反丁烯二酸(FA)和H-ZSM-11分子筛,采用流延法制备了PVA/FA/H-ZSM-11复合质子交换膜。用傅里叶变换红外光谱、X射线衍射仪、热重分析仪等对膜进行了表征,并测试了复合质子交换膜的吸水溶胀率和质子电导率等性能。结果表明,当PVA/FA/H-ZSM-11复合质子交换膜中m(PVA)∶m(FA)∶m(H-ZSM-11)质量比为12∶0.5∶1时,完全水合24 h时电导率最高为13.59×10~(-2)s·cm~(-1),吸水溶胀率为14.17%,H-ZSM-11分子筛的加入在抑制了复合质子交换膜溶胀性的同时提高了质子电导率,其溶胀过程符合Scott二阶溶胀动力学模型,且复合质子交换膜的热稳定性较好。     

纳米SiO2/SPFEK复合质子交换膜的制备及性能

以自制的磺化聚芴醚酮和正硅酸乙酯为原料,采用溶胶凝胶(Sol-gel)法合成了掺杂纳米SiO2的复合质子交换膜,利用能量分散谱(EDS)线扫描、热失重分析法、扫描电镜对膜的结构、热稳定性、微观形态进行了表征。并考察了质子交换膜的各种性能。结果表明,纳米SiO2能提高膜的质子传导率和氧化稳定性能。当SiO2掺杂质量分数为9%时,复合膜的质子传导率在80℃时为5.96×10-2(S/cm),在80℃的Fenton’s试剂(3%的过氧化氢和2 mg/L的FeSO4)中进行氧化稳定性测试,膜在117 min时才开始碎裂,表现出良好的氧化稳定性。     

有机膦酸掺杂聚乙烯醇电解质膜的制备与性能

以聚乙烯醇(PVA)为基体,戊二醛(GA)为交联剂,通过溶液浇注法,将3种有机膦酸(OPA)2-羟基膦酸基乙酸(HPAA)、2-膦酸丁烷-1,2,4-三羧酸(PBTCA)、氨基三亚甲基膦酸(ATMP)掺杂到聚乙烯醇中,制备新型的磷酸化质子交换膜。利用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TGA)、交流阻抗谱等对磷酸化质子交换膜的结构和性能进行了研究。结果表明,OPA的加入使PVA结构由晶态向非晶态转变,且有效地提高了PVA复合膜的质子电导率,并随着OPA含量的增加,其质子电导率也随之增加,当OPA的质量分数为6.7%时,室温下,其电导率最高可达5.79×10-3S/cm,膜的力学性能有一定的下降。     

磺化聚芳醚酮砜/PVA复合质子交换膜的制备与性能

为了进一步提高质子交换膜在中高温时的质子导电率,文中以高磺化度的磺化聚芳醚酮砜(SPAEKS)和聚乙烯醇(PVA)为原料,通过溶液共混法制备了PVA不同含量的磺化聚芳醚酮砜/PVA复合膜。通过对复合膜的性能测试发现,PVA的引入提高了膜的热稳定性、吸水率和保水能力。而且SPAEKS/PVA复合膜的质子传导率高于SPAEKS膜,在80℃时,复合膜的质子传导率都在0.07 S/cm以上,能够满足中高温质子交换膜燃料电池的使用要求。     

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 ...     

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     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.