有机改性蒙脱土基复合相变材料的制备及相变动力学分析

以癸酸(CA)、肉豆蔻酸(MA)、硬脂酸(SA)三元低共熔物为相变材料,有机改性蒙脱土(OMMT)为层状封装材料,采用熔融浸渗法制备 CA-MA-SA/OMMT 复合相变材料,相变材料和层状材料的最佳质量比 m(CA-MA-SA)∶m(OMMT)=7∶3。采用 X 射线衍射(XRD)、红外光谱(FT-IR)和差示扫描量热分析(DSC)对复合相变材料的结构、性能进行表征。结果表明：三元脂肪酸低共熔物被有效封装在改性后的蒙脱土层间,复合相变材料的相变温度为20.14℃,相变潜热为89.14 J·g-1。相变动力学分析结果,复合相变材料的相变反应级数为1.18,活化能为14.22 kJ·mol-1。活化能说明低共熔物与蒙脱土之间是嵌合关系,不是化学吸附。     

一种定形相变贮能材料的制备

本实验探讨了利用熔融插层法将棕榈酸插入到蒙脱土层间制备定形相变贮能材料的方法,研究了其适宜的制备条件,用XRD、IR、DSC等方法对定形相变材料的结构和性能进行了表征与测试.研究结果表明:棕榈酸被有效地密封在蒙脱土层间,制得的材料具有良好的贮能性能,相变贮能过程中形态稳定.     

二元脂肪酸/蒙脱土复合相变储能材料的制备及性能研究

利用溶液插层法合成了二元脂肪酸/蒙脱土复合相变储能材料,并通过XRD、FT-IR、DSC、储放热实验和稳定性实验对复合相变材料的结构、储热性能和稳定性进行了表征.结果表明,二元脂肪酸进入到蒙脱土的纳米层间,形成稳定的复合体系,这种复合相变材料具有优良的结构性能和良好的储热、传热性能,并且经过1000次连续储放热后,复合相变材料的相变温度和相变潜热变化不大,表现出较高的稳定性,具有相对长效的储放热功能,可望在节能方面得到广泛的应用.     

石蜡/蒙脱土纳米复合相变材料的制备及分析

为了制备具有较好导热性能、潜热密度较大的相变材料,首先利用蒙脱土在水中分散,制得搭接结构的水凝胶,然后将熔融态的相变材料加入到蒙脱土(MMT)水凝胶中,进行高速分散,XRD和DSC结果显示,所制材料为具有纳米结构的复合相变材料.     

十二醇/蒙脱土复合相变储能材料的制备及性能研究

采用超声震动和液相插层相结合的方法制备出十二醇/蒙脱土复合储能材料.用XRD、IR、SEM、DSC等方法对其结构及储能性能进行了研究.结果表明,复合相变材料具有较适宜的相变温度,较高的相转变焓,较好的热稳定性,储能性能适合做建筑相变材料.     

OMMT/EP/CF三元复合材料的制备及耐热性能研究

为了提高碳纤维复合材料的热学性能及高温力学性能,通过有机化蒙脱土改性环氧树脂(EP)制备了有机化蒙脱土/环氧树脂/碳纤维(OMMT/EP/CF)三元复合材料,研究了有机化蒙脱土在环氧树脂中的插层效果,有机化蒙脱土的类型与加入份数对OMMT/EP/CF三元复合材料力学性能及热学性能的影响,同时研究了温度对OMMT/EP/CF三元复合材料的力学性能的影响.研究表明,加入了有机化蒙脱土后,复合材料的力学性能及热学性能均有较大幅度的提高,同时还表明随着温度的升高,复合材料的性能逐渐降低.     

悬浮聚合法制备纳米蒙脱土/聚合物( 苯乙烯-共聚-二乙烯基苯) 复合材料及性能

采用悬浮聚合法制备了纳米蒙脱土/聚合物(苯乙烯-共聚-二乙烯基苯) 复合材料。钠基蒙脱土(SMMT) 经十六烷基三甲基溴化铵(CTAB) 离子交换后获得有机蒙脱土(OMMT) 。采用XRD 和FTIR 分析表征了有机蒙脱土的结构与性能。通过XRD、TEM、SEM、和FTIR 对复合材料微观结构进行了表征; 通过热重分析仪( TG) 对复合材料的热稳定性能进行了研究。讨论了蒙脱土含量和交联剂用量对复合材料热稳定性能的影响。结果表明, 钠基蒙脱土的层间距为1. 48 nm , 经有机改性蒙脱土的层间距为2. 85 nm , 纳米蒙脱土/聚合物复合材料的层间距约为4 nm; 纯聚苯乙烯最大质量损失温度为399 ℃, 当蒙脱土含量为5 %、交联剂用量为10 %时, 纳米蒙脱土/聚合物最大质量损失温度提高到437 ℃。在实验条件下, 纳米蒙脱土/聚合物复合材料具有更好的热稳定性能。      

脂肪族聚氨酯弹性体/蒙脱土复合材料的制备与性能

使用原位插层聚合法制备了一系列不同有机蒙脱土含量的基于异佛尔酮二异氰酸酯的脂肪族聚氨酯弹性体/蒙脱土纳米复合材料,通过X射线衍射(XRD)、差示扫描量热测试(DSC)、热重分析(TGA)等研究了有机蒙脱土含量对脂肪族聚氨酯弹性体结构与性能的影响。XRD结果表明,成功地合成了聚氨酯/蒙脱土插层型纳米复合材料。TGA结果表明,纳米复合材料的热稳定性随着有机蒙脱土含量的增加而提高。有机蒙脱土对聚氨酯基体有较好的增强和增韧作用,而当有机蒙脱土含量为7%时,纳米复合材料的力学性能最佳。     

CA-SA/OMMT/PMMA复合相变储能材料的制备与性能研究

以癸酸(CA)/硬脂酸(SA)共熔物、有机蒙脱土(OMMT)、甲基丙烯酸甲酯(MMA)为原料,偶氮二异丁腈(AIBN)为引发剂,采用本体聚合法制备一种脂肪酸类复合相变储能材料。采用电子扫描显微镜、光学显微镜、红外光谱仪、差示扫描量热仪、热重分析仪等对复合相变储能材料的表面形态、化学结构、热性能及热稳定性等进行测试,并对渗漏性及储热调温效果进行了评价。结果表明:脂肪酸与基体材料的复合方式为物理共混,该复合相变储能材料具有较好的相变蓄热性能及热稳定性。脂肪酸与有机蒙脱土的质量分数分别为60%、10%时,复合相变储能材料中的脂肪酸共熔物泄漏少,相变温度为20℃,相变焓为69.3J/g。     

聚丙烯/蒙脱土纳米复合材料的制备和表征

用熔融插层法制备了聚丙烯/蒙脱土纳米复合材料。X射线衍射测试(XRD)表明,制备的纳米复合材料均为插层型。扫描电镜(SEM)观测到纳米复合材料没有明显的有机无机相畴,即蒙脱土和聚丙烯有较好的相容性。差热分析测试(DSC)表明,蒙脱土的加入,对复合材料的熔点影响不大。热重分析测试(TGA)表明,蒙脱土的加入,使复合材料的热稳定性得到很大提高。动态热机械分析测试(DMTA)表明,蒙脱土的加入使储存模量得到很大提高,玻璃化转变温度略有下降。     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.