含磷双酚A甲醛酚醛环氧树脂的合成与反应动力学研究

含磷环氧树脂是目前阻燃环氧树脂的主要发展方向,其在电子工业和复合材料方面有广泛的应用.本方法采用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与双酚A甲醛酚醛环氧树脂合成了新型含磷双酚A甲醛酚醛环氧树脂,通过红外谱图和核磁共振图谱确认了其结构,并简单的探讨了反应机理;采用DSC分析方法研究DOPO与双酚A甲醛酚醛环氧树脂的反应动力学,得到DOPO与双酚A酚醛环氧树脂反应的表观活化能Ea为54.379kJ/mol,反应级数n为1.08,表明该反应为一级反应.     

环氧树脂/聚丙烯酸酯复合乳液的制备Ⅰ:丙烯酸酯单体及聚合对环氧树脂乳胶粒的溶胀行为

采用环氧树脂/聚乙二醇嵌段共聚物为乳化剂及相反转法制备了环氧树脂E-44水乳液,探讨了乳化剂用量对相反转点的影响,以及相反转搅拌速度对环氧树脂乳胶粒子粒径的影响.结果表明,随乳化剂用量的增加,相反转点变小;随搅拌速度的增加,乳液的平均粒径显著减小.探讨了丙烯酸酯类混合单体及聚合反应对环氧树脂乳胶粒的溶胀行为.结果表明,混合单体对环氧树脂乳胶粒子有溶胀作用,当单体与环氧树脂的质量比(Mm/MEP)达到0.8时,乳胶粒被胀破,但复合预乳液的稳定性并未下降;聚合后,环氧树脂乳胶粒的平均粒径进一步增大且分布变宽,当Mm/MEP达到0.6后,部分乳胶粒因粒径过大而发生沉降.     

硅氧烷改性环氧树脂复合水分散液的制备及粒径研究

采用化学方法制备了稳定的硅氧烷改性环氧-苯丙复合水分散液,红外光谱表征聚合物结构,动态激光光散射测量水分散液粒径及其分布,透射电镜观察粒子形态。结果表明:环氧树脂的改性是化学改性,当m(苯丙单体)∶m(环氧树脂)=10∶7.95,亲水单体(M AA)含量为22.2%,硅氧烷含量为2%时,水分散液粒径最小、最稳定。放置时间对水分散液粒径影响不大。改性后粒子呈不规则的球形,粒径减小。     

改性环氧树脂灌封材料的研制

用端羧基丁腈橡胶(CTBN)与环氧树脂AG-80反应制得改性环氧树脂(Ⅰ);以硅硼树脂与双酚A型环氧树脂反应得到改性环氧树脂(Ⅱ);将改性环氧树脂(Ⅰ)和(Ⅱ)按比例在室温下充分混匀为A组分,把固化剂、阻燃剂等混配成B组分,将A和B组分按不同配比均匀混合配成灌封材料,并以IR、拉力机等仪器分别对改性树脂、灌封材料进行结构及力学性能的测试表征.筛选出的最佳固化条件为,当A组分与B组分用量为25:1时,于80～100℃固化2～4h,可得到理想的灌封效果.     

聚醚型聚氨酯/环氧树脂互穿网络聚合物的结构与性能研究

以4,4’-二苯基甲烷二异氰酸酯和聚醚及双酚A型环氧树脂为原料经共聚合成了聚氨酯(PU)/环氧树脂(EP)互穿聚合物网络(IPNs).通过改变聚氨酯结构及环氧树脂含量制备系列PU/EP的IPNs,并对其性能进行了研究.研究表明随着聚氨酯中两官能度聚醚用量增加,IPNs体系的亲水性增强、表面自由能增大;此外随着环氧树脂含量增多,整个IPNs体系的疏水性增强;力学性能测试表明,聚氨酯结构以及环氧树脂含量对PU/EP的IPNs材料力学性能影响较大.     

一种新型耐热聚合物——酞菁树脂

一、前言空间技术等部门已采用环氧树脂和聚酰亚胺作为胶粘剂、涂料、密封材料及纤维增强复合材料,但这两种树脂各自都有不足之处。环氧树脂只能在200℃以下使用,而聚酰亚胺则加工性能差,更由于其酰亚胺化是化学反应,在固化(即酰亚胺化)过程中要放出低分子,因而使其应用范围受到限制。近年来一些科学家开发了一类酞菁聚合物,这种新型耐热树脂由双邻苯二甲腈基化合物经环化聚合而成。单体的结构通式为:     

互穿网络型乙烯基酯树脂/环氧树脂的增韧与热性能

使用双酚A型环氧乙烯基酯树脂(VER)与双酚F型环氧树脂(EP)同步固化的方法对环氧树脂进行增韧改性.研究了共混体系的固化反应过程、力学和热性能以及形态结构.结果表明,当环氧树脂与乙烯基酯树脂的质量比为90∶10时,所得到的树脂体系在韧性提高的同时,耐热性能(Tg)也有明显的提高,获得了一种兼具韧性和耐热性能的树脂基体.     

高性能萘基环氧树脂的合成

采用化学结构改性的方法,以萘酚和福尔马林溶液为原料,合成了分子骨架中相对于苯基体积较大、刚性强、平面结构、疏水性高的萘环为主链结构环氧树脂-2,2'-二缩水甘油醚基-1,1'-联萘(DGEBN)和邻邻'-二缩水甘油醚基-二萘基-亚甲基(DGEFN);然后分别以双氰双胺(DICY)、4,4'-二氨基-二苯基甲烷(DDM)、4,4'-二氨基-二苯基砜(DDS)作为固化剂,对DGEBN、DGEFN、DGEBA固化体系性质进行研究;研究结果表明,萘基环氧树脂固化物比苯基环氧树脂(DGEBA)固化物具有更高的玻璃化转变温度(Tg),极好的热稳定性和较低的吸湿性,是一种高性能的新型环氧树脂体系.     

高性能氟-硅改性核壳型纳米乳液制备及应用研究

以乙烯基三乙氧基硅烷(VTES)、甲基丙烯酸十二氟庚酯(DFMA)、丙烯酸正丁酯(BA)作为壳单体,以苯乙烯(St)、甲基丙烯酸甲酯(MMA)作为核单体,合成了氟硅改性核壳结构纳米丙烯酸乳液.研究了核壳结构及VTES、DFMA功能单体对涂膜的性能影响.采用红外光谱、激光光散射(DLS)和透射电镜(TEM)对乳液的化学结构、粒径分布和微观形貌进行表征;通过接触角测量对涂膜表面亲疏水性能进行表征.结果表明:核壳结构的纳米乳液粒径分布窄且均匀;VTES、DFMA的加入对涂膜的附着力、耐水性、耐紫外光、耐污性有提高,当VTES、DFMA加入量分别为单体总量的6％、8％时,所制得的纳米乳液的稳定性好,涂膜的综合性能好,其接触角高达110.2°,耐水性突出.     

新型磷硅改性双酚A型环氧树脂的制备及其固化反应动力学研究

采用羟基封端聚二甲基硅氧烷(HTPDMS)、9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与双酚A型环氧树脂合成了新型的含磷硅双酚A型环氧树脂,通过红外谱图以及核磁共振图确认了其结构,并简单讨论其反应机理;采用DSC分析方法研究其固化动力学,得到其与4,4’-二氨基二苯甲烷(DDM)固化的平均表观活化能Ea为40.74kJ/mol,反应级数n为0.90。     

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.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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 ...