聚丙烯基阴离子交换纤维制备工艺对其性能的影响

采用共辐射引发接枝共聚方法在聚丙烯纤维上接枝苯乙烯,通过氯甲基化和胺化反应制备强碱性阴离子交换纤维。研究了反应条件对接枝率、交换容量和纤维强度的影响。结果表明,共辐照接枝反应中,当二乙烯苯含量2%,剂量率0.5 kG y/h~1.0 kG y/h,照射时间5 h~8 h时,接枝纤维的接枝率和力学强度较高。功能化反应中,当氯甲基化反应温度40℃~45℃,反应时间15 h~20 h,胺化反应温度30℃,反应时间15 h~20 h时,制备的纤维具有较好的力学性能和较高的交换容量。     

聚丙烯基强碱性阴离子交换纤维的结构表征及性能研究

采用共辐射引发接枝共聚法在聚丙烯纤维上接枝苯乙烯-二乙烯苯,通过氯甲基化反应和胺化反应制备强碱性阴离子交换纤维.利用分析仪器对制备产品的结构进行表征,并对其溶胀性、机械强度、吸附交换性能等物理和化学性能进行了测定.结果表明,制备的强碱性阴离子交换纤维具有较高的交换容量、快的吸附速度、较好的机械性能和稳定的化学性能,是一种性能优良的离子交换材料.     

含羧基和吡啶基两性离子交换纤维的结构控制

采用X射线光电子能谱、红外、热失重-红外联用及扫描电镜等手段研究了含羧基和吡啶基两性离子交换纤维的结构,及其对金属离子和氨基酸的吸附分离特性.结果表明,两性离子交换纤维含有羧基和吡啶基,其总交换容量、阳/阴离子交换基团的比率以及纤维的表面形貌可通过选择共接枝单体对种类及其投料比来控制,从而控制两性纤维的吸附选择性随着共接枝单体吡啶组分含量的增加,阴离子交换容量逐渐上升,阴离子交换基团占总交换基团的比率也随之增加,两性纤维的表面形貌综合了两种单体单组份接枝时的特征.由于吡啶和羧基的协同作用,两性纤维对Cu2 有很大的吸附量,而且当酸碱两种基团含量接近时,协同作用更强.     

强碱性壳聚糖分离介质的制备及其性能研究

利用反相悬浮交联法制备了壳聚糖基质,基质再与环氧丙基三甲基氯化铵反应,制得强碱性的壳聚糖阴离子分离介质.研究了分离介质的最佳制备条件,测定了其最大阴离子交换容量和滴定曲线,最后用5′-鸟苷酸对其进行交换性能表征.结果表明,最佳制备工艺为:以1.0％(m/V)的NaOH为催化剂,1.0g壳聚糖基质与5.0mL环氧丙基三甲基氯化铵于50℃反应3.0h,产物为强碱性阴离子分离介质,其最大交换容量为2.88mmol/g干介质,交换吸附结果表明对5′-鸟苷酸最大吸附量为98.59mg/g干介质.     

多胺型阴离子交换纤维吸附Cr(Ⅵ)的热力学

采用自制的多胺型阴离子交换纤维,研究其对Cr(Ⅵ)的吸附特性.在研究的温度及浓度范围内,该纤维对Cr(Ⅵ)的平衡吸附量及吸附速率随温度的升高而增大.吸附是一个快速吸附过程,20min内即可达到吸附平衡,且该吸附过程符合Boyd液膜扩散模式.纤维对Cr(Ⅵ)吸附的平衡数据符合Langmuir和Freundlich吸附等温方程,且为优惠型吸附.测试了Cr(Ⅵ)在该多胺型阴离子交换纤维上的吸附焓、自由能和吸附熵,并对此吸附行为作了合理解释.结果表明,该吸附为吸热过程,升温有利于吸附的进行;多胺型阴离子交换纤维对Cr(Ⅵ)的吸附过程以化学吸附为主.     

弱酸离子交换纤维的结构表征与性能研究

采用预辐射接枝法,引发聚丙烯(PP)纤维接枝丙烯酸(AA),制备出接枝率为235%～298%,平均交换容量为9.65mmol/g,物理机械性能良好的弱酸离子交换纤维(PP-g-AA).利用分析仪器对PP-g-AA纤维的结构进行表征,并对其机械强度、热稳定性、交换容量、接枝率、化学稳定性等物理与化学性能进行了测试.结果表明,利用预辐射接枝法制备的PP-g-AA纤维具有较高的交换容量、快的吸附速度、较好的机械性能和稳定的化学性能,是一种性能优良的功能材料.     

微结构对环铵型酚酞聚芳醚砜阴离子交换膜性能的影响

制备了一系列结构微小差异的环铵型酚酞聚芳醚砜阴离子交换膜材料(PES-PPH-R-OH),并通过核磁共振氢谱对其结构进行了表征,详细评价了膜的热性能、力学性能、微相分离结构、离子交换容量(IEC)、吸水率、溶胀率及离子传导率等性能,重点研究并揭示了功能基团微小化学结构差异对相应膜性能的影响规律.研究结果表明,功能环铵基团的微小结构差异(单个元素的差别)对膜的微相分离结构、吸水率、电导率等性能有显著影响.其中,PES-PPH-Pip-OH膜具有最高的电导率,80℃时,其电导率高达83.53 mS/cm,有望成为新型阴离子交换膜并在燃料电池中得到应用.     

Structures control of carboxyl/pyridine-containing amphoteric ion exchange fibers

采用X-射线光电子能谱、红外、热失重－红外联用及扫描电镜等手段研究了含羧基和吡啶基两性离子交换纤维的结构，及其对金属离子和氨基酸的吸附分离特性。结果表明，两性离子交换纤维含有羧基和吡啶基，其总交换容量、阳/阴离子交换基团的比率以及纤维的表面形貌可通过选择共接枝单体对种类及其投料比来控制，从而控制两性纤维的吸附选择性。随着共接枝单体吡啶组分含量的增加，阴离子交换容量逐渐上升，阴离子交换基团占总交换基团的比率也随之增加，两性纤维的表面形貌综合了两种单体单组份接枝时的特征。由于吡啶和羧基的协同作用，两性纤维对Cu2＋有很大的吸附量，而且当酸碱两种基团含量接近时，协同作用更强。     

三聚氰胺协同戊二醛联合交联QCS构筑燃料电池用阴离子交换膜EI北大核心CSCD

以三聚氰胺为中间改性物,借助戊二醛作为交联剂改性季铵化壳聚糖制备阴离子交换膜。通过改变三聚氰胺含量,探讨其作为交联中间体对阴离子交换膜力学性能、导电性能以及耐碱稳定性等相关性能的影响,并对其进行扫描电镜观测微观结构。扫描电镜结果表明,三聚氰胺与季铵化壳聚糖交联过程中,膜表面呈现褶皱状,形成致密连续的膜结构。三聚氰胺引入后,膜的力学性能、导电性能及耐碱稳定性均得到改善,当三聚氰胺含量达到4%时,膜样品拉伸强度可达到33.79 MPa,在70℃时其导电率达4.83×10^(-2)S/cm,将膜浸渍于6 mol/L KOH(60℃)中120 h,电导率仅损失2.81%,表现出优异的耐碱稳定性。     

季铵化聚砜/改性蒙脱土阴离子交换膜的制备与表征

以聚乙烯亚胺(PEI)和二甲基二烯丙基氯化铵-丙烯酰胺共聚物(PAADDA)为改性剂,对蒙脱土K10纳米片进行了包覆。将改性K10添加于氯甲基化聚砜的N,N-二甲基乙酰胺溶液中制备复合膜,经季铵化和碱化处理得到复合的阴离子交换膜。采用傅里叶变换红外光谱、X射线衍射仪、热重分析仪对改性蒙脱土和阴离子交换膜进行了表征,并测试了阴离子交换膜的吸水率、力学性能和离子传导率。结果表明,PEI和PAADDA成功包覆于K10纳米片表面,复合的阴离子交换膜吸水率、热稳定性和力学性能与季铵化聚砜膜相比都有明显改善,PAADDA改性K10含量为5%的阴离子交换膜具有最高的离子传导率,60℃时超过3.0×10-2S/cm。     

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.