纳米尺度PS/Ag核壳结构复合球的制备与表征

采用分步法制备了聚苯乙烯/银(PS/Ag)核壳结构复合纳米球。首先采用无皂乳液聚合法并利用丙烯酸(AA)的羧基对制备的PS球进行改性,使其表面带负电荷;然后通过静电吸附作用在改性PS球的表面沉积[Ag(NH3)2]+,水浴(80℃)环境中利用十二烷基磺酸钠(SDS)作为还原剂将PS球表面的[Ag(NH3)2]+还原,制备出PS/Ag核壳结构复合球。通过动态激光粒度分析仪和透射电子显微镜对PS/Ag核壳纳米球的粒度分布、形貌和结构进行了表征,研究了AA的用量对复合球粒径及包覆的Ag壳厚度的影响。结果表明,随着AA用量的增大,所包覆的银层更加致密,厚度增大,当AA用量为15%时可得到Ag完全包覆的PS/Ag复合纳米球。     

内核尺寸对核/壳结构PS/SiO_2复合磨料抛光特性的影响

核/壳结构有机/无机复合微球作为一种新型抛光介质,在实现高效无损伤抛光方面具有重要的应用价值。以无皂乳液聚合法制备的聚苯乙烯(PS)为内核,通过溶胶-凝胶法合成了一系列具有不同内核尺寸的PS/SiO2复合微球。利用FT-IR、FESEM和TEM等手段对样品进行表征,并借助AFM考察了复合磨料内核尺寸对SiO2介质层抛光质量的影响规律。结果表明,所制备单分散PS微球尺寸在200~600 nm,复合微球的壳层由SiO2纳米颗粒(5~10nm)所组成,壳厚在10~15 nm。材料去除率(MRR)随复合磨料内核尺寸的减小而降低,而抛光后晶片表面粗糙度(RMS)的变化则不明显。当复合磨料内核尺寸为210 nm时,抛光后RMS和MRR分别为0.217 nm和126.2 nm/min。提出将核壳结构有机/无机复合磨料理解成一种表面布满无机纳米颗粒的微型"抛光垫",尝试用有效磨料数量以及壳层中单个SiO2颗粒的压入深度对CMP实验结果进行解释,并进一步讨论了有机内核在抛光过程中的作用。     

PS/SiO2纳米杂化材料的制备及作为菜籽油添加剂的摩擦学性能

用无皂乳液聚合法一步制备了聚苯乙烯/表面有机化二氧化硅（PS/SiO2）纳米杂化材料，采用红外光谱（FF-IR）、透射电子显微镜（TEM）以及热分析（TGA-DSC）等对材料的核-壳结构进行了表征，表明PS/SiO2纳米杂化材料为平均粒径在60nm左右的良好分散圆球。利用四球机考察了添加剂在菜籽油中的摩擦学性能。结果表明，合成的PS/SiO2纳米杂化材料能提高菜籽油的抗磨性能及承载能力，并能降低摩擦系数，其最佳用量为1.0％。     

功能性聚丙烯酰胺类微球的制备及应用

介绍了功能性聚丙烯酰胺类微球的各种制备方法,主要为分散聚合法和无皂乳液聚合法。其中重点介绍了改进的无皂乳液聚合法-超声波无皂乳液聚合法、紫外光引发无皂乳液聚合法和微波加热无皂乳液聚合法;同时,还介绍了功能性聚丙烯酰胺类微球的种类和应用,诸如:温敏性聚丙烯酰胺微球、磁性聚丙烯酰胺微球、pH值响应聚丙烯酰胺类微球以及聚丙烯酰胺与无机微粒形成的复合微球。并对功能性聚丙烯酰胺类微球研究作了展望。     

微米级PVDAT@PS微球的制备及生物应用研究

该研究首次利用功能单体2-乙烯基-4,6-二氨基-1,3,5-三嗪(VDAT)在水相中合成具有生物应用前景的微米级核壳微球。首先,我们利用分散聚合制备出了微米级,单分散,且表面带有足够负电荷的聚苯乙烯微球(PS)模板。再利用半连续无皂乳液聚合法在阳离子引发剂的作用下,于水相中将微溶于热水的单体VDAT引发聚合。通过静电作用将带正电荷的VDAT聚合物(PVDAT)包覆于带负电荷的PS微球表面,成功合成PVDAT@PS功能微球。最后利用该功能微球对不同双链DNA的吸附,初步研究其在生物领域的应用。     

核壳结构TiO2/Ag反蛋白石的制备与形貌观察

用化学还原法制备了银包覆聚苯乙烯(PS)微球结构,通过垂直沉积法排列出具有密堆积结构的PS-Ag蛋白石模板,然后采用溶胶-凝胶法渗透TiO2,最后焙烧处理除去PS,制备出了规整的核壳结构TiO2/Ag反蛋白石。采用扫描电镜、透射电镜和X射线衍射对该样品进行了分析。结果表明,PS球表面包覆的为纳米尺度的金属Ag;所制备的PS/Ag核壳微球蛋白石经过480℃、12h焙烧处理后获得的核壳TiO2/Ag反蛋白石结构的单胞参数可以通过调节包覆银层的厚度来调变,即改变AgNO3与PS球的质量比获得具有不同银包覆层厚度、不同单胞参数的三维蛋白石和反蛋白石结构。     

静电凝聚法制备苯乙烯-丙烯酸共聚物/氧化铈核壳纳米复合材料

致力于苯乙烯-丙烯酸共聚物(P(St-co-AA))微球/氧化铈核壳纳米结构的制备,以无皂乳液聚合制备的P(St-co-AA)微球为负电组成,水热法合成的氧化铈纳米粉体为正电组成,设计了静电凝聚法复合工艺,对复合工艺条件进行了初步的探索。结果表明:采用无皂乳液聚合制备的P(St-co-AA)微球呈正球形,颗粒尺寸均一,尺寸在160~390nm范围内可控;以CTAB为表面活性剂,采用水热法在100℃条件下成功制得了颗粒尺寸在10~20nm的氧化铈纳米粉体。在水溶液体系中,在静电凝聚作用下,所制备氧化铈在P(St-co-AA)微球表面紧密堆积,形成了P(St-co-AA)/氧化铈核壳结构。可通过调节P(St-co-AA)微球的尺寸与负电性以及复合过程中pH值来调控所得核壳结构形貌。正负颗粒电性的匹配是构筑核壳结构的关键,一味地增加颗粒表面正电性或负电性对于实现调控复合过程形成纳米核壳结构并非有利。当苯乙烯与丙烯酸单体比例为10∶1时所得P(St-co-AA)微球在pH 2.0~3.0下所得核壳结构形貌均一,分散性较好。     

乳液聚合法制备核壳纳米粒子研究进展

核壳结构纳米复合颗粒因其特殊的结构而呈现出独特的物理、化学性能,具有广阔的应用前景。介绍核壳纳米复合材料的2类制备方法,综述了乳液聚合法制备核壳结构纳米微球的研究近况,主要分析了传统乳液聚合、微乳液聚合、细乳液聚合以及无皂乳液聚合等制备技术,展望了乳液聚合法制备核壳结构纳米微球的发展趋势。     

有机微球填充水性环氧涂层的制备及其防腐性能

用无皂乳液聚合法制备单分散的聚甲基丙烯酸甲酯(PMMA)和聚苯乙烯(PS)微球,将其添加到水性环氧树脂中制备出有机微球/水性环氧复合涂料,然后用空气喷涂法在钢片表面制备出复合涂层。用动态光散射(DLS)和扫描电子显微镜(SEM)对制备的有机微球进行了表征,用电化学测试(EIS)、盐雾测试和附着力测试等手段研究了不同颜基比(颜料和树脂的质量比:P/B)的有机微球/水性环氧复合涂层的耐蚀性。结果表明,两种有机微球的粒径均一且具有高度的单分散性,颜基比P/B=0.007的PS/水性环氧复合涂层具有最佳电化学、耐盐雾和附着力性能。复合涂层的抗介质渗透能力明显优于清漆涂层,因为有机微球独特的表面效应提高了涂层的致密性。     

胶晶/嵌段共聚物双重模板制备多级孔材料

采用分段乳液聚合法和无皂乳液聚合法制备了聚苯乙烯(PS)微球,以此单分散胶态晶体和嵌段共聚物P123为模板剂,通过Y型分子筛前驱体的填充和模板剂的去除制备了具有大-介-微多级孔的材料.采用XRD、SEM和TEM等手段表征了PS微球及多级孔材料.结果表明,分段乳液聚合可以制备平均粒径为50nm的PS微球,无皂乳液聚合可以制备450nm左右的PS微球;以其作为大孔模板剂分别考察了PS微球粒径、模板剂用量、水用量等因素对多级孔材料合成的影响,结果表明,PS微球的粒径越大,材料中大孔的分散性越好.合成多级孔材料的条件为:PS微球乳液与前驱体的比值(质量比)为1.0~0.5,水与前驱体的比值为7.5,P123与前驱体的比值为0.1.     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to