高性能端芳香氨基聚醚/环氧树脂胶粘剂的研究

用端芳香氨基聚醚(ATPE)与E-44环氧树脂组成了高强、高韧的胶粘剂.研究了胶粘剂的固化反应和固化产物的交联密度、冲击断面形貌与力学性能,及其随ATPE化学结构变化的规律.结果表明,增大ATPE分子中聚醚链段长度(M^-PE),胶粘剂体系的固化温度和反应热焓值(ΔH)均提高;胶粘剂固化产物的综合力学性能随着M^-PE增大出现最佳值.改变ATPE中末端-NH2在苯环上的位置,发现3-ATPE体系的ΔH最大;2-ATPE体系的综合力学性能最佳.     

CTBN含量对环氧胶粘剂性能的影响

以端羧基丁腈橡胶(CTBN)和环氧树脂E-44为原料,选用二月桂酸二丁基锡为催化剂,制得EP-CTBN接枝预聚物,并以4,4′-二氨基二苯砜为固化剂制得环氧胶粘剂,并将其应用于挠性覆铜板(FCCL)。通过红外光谱和环氧保留率的测定,研究了预聚物制备的反应过程;通过SEM、TG和力学性能的测试,探讨了CTBN含量对环氧胶粘剂性能的影响。结果表明:CTBN的端羧基与E-44的羟基发生了酯化反应,在固化过程中橡胶支链从基体中析出而形成均匀孔洞结构;随CTBN含量的增加,环氧胶耐热性提高;当CTBN用量为50%(wt,质量分数,下同)时,FCCL剥离强度达到1.30N/mm、耐折次数为5149次,均达到FCCL行业标准。     

有机硅嵌段改性聚氨酯/环氧树脂互穿网络聚合物的研究

以甲苯-2,4-二异氰酸酯(TDI)、聚醚二元醇为主要原料制得-NCO封端的预聚体,并按一定比例和环氧树脂E-51混匀;另外合成一系列分子量不同的氨基聚硅氧烷(AG),并利用多元胺类作固化荆,合成一系列氨基聚硅氧烷改性的聚氨酯／环氧互穿网络聚合物。测试了材料的力学性能、表面接触角、吸水率,同时对材料进行了红外光谱和表面电子能谱(ESCA)分析。结果表明,氨基聚硅氧烷／聚氨酯／环氧互穿网络聚合物是一种具有良好疏水性能的新型低表面能材料,同时其力学性能的变化与氨基聚硅氧烷的含量以及分子量的大小等密切相关。     

改性阻燃环氧树脂胶粘剂的研制

以三聚氰胺聚磷酸酯(MPP)为阻燃剂,以聚酯型聚氨酯预聚体改性环氧树脂E-44为基体,制备改性阻燃环氧树脂胶粘剂.通过对改性基体材料进行电子探针(EPMA)以及冲击强度测试,对改性阻燃胶粘剂进行剪切强度、热稳定性以及阻燃性能测试,从而确定了聚氨酯与阻燃剂用量对胶粘剂性能的影响.结果表明:环氧树脂100份,聚氨酯预聚体30份,阻燃剂30份,制备的改性阻燃胶粘荆具有优异的韧性和阻燃性能,其拉伸剪切强度为21.3MPa,氧指数达29.6.     

自修复环氧胶粘剂分子设计

在自修复聚合物复合材料中,修复剂黏度和高聚物强度是保证自修复过程实现的重要因素。文中以合成用于自修复材料的环氧树脂微胶囊为目的,在双酚A型环氧树脂(E-51)中加入稀释剂正丁基缩水甘油醚(BGE)降低黏度,采用傅里叶红外(FT-IR)分析稀释剂对环氧胶粘剂与微胶囊咪唑类固化剂交联反应的影响,表征了在固化过程中稀释剂参与环氧胶粘剂与咪唑类固化剂的交联反应;使用差示扫描量热(DSC)技术对该固化反应进行动力学研究,确定出稀释剂的最佳用量;通过拉伸实验测定了环氧树脂固化产物的强度,表明BGE的加入增强了环氧树脂的胶粘性能。     

环氧/丁腈胶粘剂的两相结构、形态及性能

使用E-51环氧树脂、端胺基丁腈橡胶(ATBN)、液态芳香二胺(E100)制备了一系列不同ATBN含量的环氧-丁腈胶粘剂。利用SEM、DMTA、应力-应变、抗剪切强度测试手段研究了不同ATBN含量的试样的相态结构、断面形貌以及力学性能。结果表明,随着ATBN/E-51比例的递增,试样由“海-岛”结构(软相为岛)过渡到两相共连续结构,接着又回到“海-岛”结构(硬相为岛)。试样的相分离受固化速率和相分离速率相互竞争的影响,所形成的两相结构胶兼具橡-塑特性,在宽温域(-50℃~75℃)具有优秀的延伸率、粘合强度。     

固化剂对聚酰亚胺挠性覆铜板剥离强度的影响

采用双氰胺(DICY)、间苯二胺(m-PDA)、长链柔性二胺(DAMI)固化双酚A型环氧树脂(E-51),制备了三种环氧胶粘剂,分别考察了三种固化剂对挠性覆铜板剥离强度的影响。根据差示扫描量热仪(DSC)曲线,通过t-β外推法得到了各固化剂固化环氧胶粘剂的固化工艺。采用扫描电子显微镜(SEM)考察其不同的破坏形式。结果表明,采用双氰胺固化的环氧胶粘剂粘接的挠性覆铜板,剥离后聚酰亚胺薄膜、铜箔表面都留有大量的胶粘剂,此破坏形式属于内聚破坏。同时双氰胺固化的环氧胶粘剂剥离强度最高,粘接强度达到0.74 N/mm,符合日本JPAC行业标准。     

钛酸酯催化环氧树脂固化动力学研究

用FTIR“原位”技术,研究了钛酸酯(Tc-114)偶联剂对环氧E-44和二氨基二苯基甲烷(DDM)固化反应的催化作用,得出固化程度与时间的关系曲线。又根据DSC曲线,分别算出加有Tc-114和不加Tc-114的两个固化体系的反应表观活化能和反应级数。结果表明,Tc-114的存在使环氧固化反应活化能降低,催化作用明显。     

苯氧基改性聚氨基环三磷腈对环氧树脂固化物的阻燃作用

通过极限氧指数(LOI)测定、垂直燃烧试验和锥形量热分析研究了苯氧基改性聚氨基环三磷腈(PPHACTPA)对酚醛胺固化环氧树脂(E-44/NX-2003)的阻燃作用,并与聚氨基环三磷腈(PHACTPA)进行了比较。结果表明,PPHACTPA对E-44/NX-2003的阻燃作用与PPHACTPA中苯氧基的数量有关。当每个磷腈环约含有1个苯氧基时(PPHACTPA-1),其阻燃作用略优于PHACTPA,而每个磷腈环所含苯氧基数增至2(PPHACTPA-2)时,其阻燃作用明显降低,差于PHACTPA。PHACTPA和PPHACTPA主要是通过凝聚相机理对E-44/NX-2003产生阻燃作用。阻燃剂在高温下生成具有强脱水作用的磷酸类化合物而促进环氧树脂固化物炭化,同时环氧体系分解生成的惰性气体使炭层发泡形成膨胀性炭层。这种致密的膨胀性炭层通过隔热隔氧及抑制环氧体系进一步地分解而产生阻燃作用。PPHACTPA-1更易转变成磷酸类化合物,因而促进成炭的能力更强,阻燃作用更好。PPHACTPA-2含磷量低,因而促进成炭的能力较差,阻燃作用较弱。     

高附着力聚脲胶粘剂的制备和性能

利用芳氨基的空间位阻效应,分别以芳香族端氨基聚醚、芳香族端氨基聚醚改性的HDI作为聚脲的A、B组分,制备了一种力学性能优异的聚脲胶粘剂。考察了A、B组分配比对胶粘剂力学性能的影响,并利用FT-IR光谱对涂层的氢键化程度进行了分析。研究结果表明,当B/A的质量比为1.55时,涂膜与金属铝材的附着力最高,达25.98MPa,其完善的氢键化程度仅为4.31%。说明芳环的引入降低了聚脲基团中NH的分子间氢键,而使其游离出来与金属底材形成胶粘点,从而提高了聚脲胶粘剂的附着性能。     

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.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.