非对称型联苯酯类液晶的制备与性能研究

以联苯双酚为起始原料,在KI的催化下与溴代正戊烷进行Williamson Ether的合成。溴丙烯与对羟基苯甲酸反应后即用氯化亚砜酰化,并与之前所制的联苯单醚酯化成4-烯丙氧基苯甲酸酯-4′-戊氧基-3,3′,5,5′-四甲基联苯。对合成的非对称型联苯酯类液晶化合物结构进行了红外和核磁表征,最后通过差示扫描量热仪(DSC)和TG对化合物的热重进行分析,并通过热台偏光显微镜(POM)进一步研究了非对称型联苯酯类化合物的材料性能。     

基于一种新型含菲并咪唑基二胺单体的聚酰亚胺的合成与性能

通过三步反应合成了一种新型具有高度扭曲构型的芳香二胺单体1,2-双(4-(4-氨基-2-三氟甲基苯氧基)苯基)-菲并[9,10-d]咪唑(PIPOTFA),将它与四种商业化二酐4,4′-六氟异丙基邻苯二甲酸酐(6FDA)、3,3′,4,4′-二苯醚四甲酸二酐(ODPA)、3,3′,4,4′-联苯四甲酸二酐(BPDA)和3,3′,4,4′-二苯甲酮四甲酸二酐(BTDA)通过高温一步法聚合制得了四种聚酰亚胺均聚物。这些聚酰亚胺在N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)和N,N-二甲基甲酰胺(DMF)等非质子极性溶剂中均具有良好的溶解性。热分析测试结果表明,这些聚酰亚胺具有优异的热稳定性,其玻璃化转变温度在265～290℃之间,氮气气氛下5%和10%热失重温度分别为517～561℃和547～587℃,700℃时的残炭率为60%～70%。这些聚酰亚胺薄膜呈淡黄色,在450nm处的透过率为11%～68%,截止波长为375～383nm。     

3,3’,5,5’-四甲基联苯-4,4’-二羟乙基醚的合成与表征

以3,3’,5,5’-四甲基联苯二酚(TMBP)和2-氯乙醇为原料两步法合成了3,3’,5,5’-四甲基联苯-4,4’-二羟乙基醚。探讨了反应物物质的量比、碱用量、催化剂及反应温度对转化率的影响。结果表明,在n(TMBP)∶n(NaOH)∶n(2-氯乙醇)=1∶3.0∶2.5,反应时间为10h,反应温度为110℃条件下,总转化率达95.9%,纯度达99.1%。并用红外、质谱以及核磁等方法对产物结构进行了表征。     

3,3′-二甲氧基联苯醌二亚胺与苯环和噻吩共聚物的金属配合物催化法制备及性质

Ni(II)配合物为催化剂,具有给电子基团甲氧基的N,N′-二氯-3,3′-二甲氧基联苯醌二亚胺分别与1,4-二溴苯,2,5-二溴噻吩共聚得到了相应的聚合物:聚(3,3′-二甲氧基联苯醌二亚胺-苯)(聚合物-Ⅰ)和聚(3,3′-二甲氧基联苯醌二亚胺-噻吩)(聚合物-Ⅱ)。单体通过1H-NMR和红外光谱进行了表征。所得聚合物的红外光谱、紫外-可见吸收光谱以及循环伏安特性等性能进行了探讨。结果表明,聚合物-Ⅰ和聚合物-Ⅱ分别在317、506、329、385、430nm处出现吸收峰。循环伏安图表明所得聚合物有一定的电化学活性。     

3,3',5,5'-四甲基-4,4'-二氨基二苯甲烷及其聚酰亚胺的制备及其性能研究

以2,6-二甲基苯胺为原料,通过一步反应制备了3,3′,5,5′-四甲基-4,4′-二氨基二苯甲烷(TMDDM),并对其结构进行表征。将TMDDM、4,4′-二氨基二苯醚(ODA)与4,4′-氧双邻苯二甲酸酐(ODPA)以不同的配比进行三元共聚,通过热亚胺化合成了6种TMDDM/ODA/ODPA-聚酰亚胺(PI)薄膜,随后对6种薄膜进行了结构表征和性能研究。结果表明:6种PI薄膜具有优良的热性能、疏水性、紫外-可见光透过率、机械性能和溶解性。     

砜基取代高折射率高透明性聚酰亚胺的合成与性能

首先合成了同时含有砜基与硫醚键的二胺单体,4,4′-双(4-胺基苯硫基)二苯砜(BADPS).采用BADPS分别与4种二酐单体,3,3′,4,4′-联苯四羧酸二酐(BPDA)、3,3′,4,4′-二苯醚四羧酸二酐(ODPA)、4,4′-双(3,4-二羧基苯硫基)二苯硫醚二酐(3SDEA)以及1,2,3,4-环丁烷四羧酸二酐(CBDA)通过两步聚合工艺制备了一系列聚酰亚胺(PI).制备的PI薄膜具有优良的综合性能,包括良好的热稳定性、可见光波长范围内优良的透明性以及高折射率与低双折射.10mm厚的PI薄膜在450nm处的透光率超过80%.全芳香族PI(PI-1～PI-3)的折射率＞1.70,双折射＜0.02.     

空穴传输材料TTB的合成及其在有机光导体中的应用

以对甲苯胺的自身缩合反应制备4,4’二甲基二苯胺,收率为50.28%;再与4,4’二碘联苯经乌尔曼反应合成了N,N,N’,N’四(4甲基苯基)[1,1’联苯]4,4’二胺(TTB),收率为84.56%。通过紫外吸收光谱、红外吸收光谱、质谱、高效液相色谱以及元素分析对产物的组成和结构进行了鉴定。用合成的TTB作为空穴传输材料制成功能分离型有机光导体,测得其静电特性数据为V0=-860V,VR=-50V,E1/2=0.3lx.s。实验证明TTB是一种性能优良的空穴传输材料。     

一类含双叔丁基苯结构聚酰亚胺的合成与性能

通过分子设计制备一种含双叔丁基结构的刚性芳香二胺单体——4,4′-二氨基苯基-3″,5″-二叔丁基甲苯,将该二胺单体分别与3种不同的商品化芳香二酐(3,3′,4,4′-联苯四酸二酐(BPDA)、3,3′,4,4′-二苯醚酐(ODPA)、3,3′,4,4′-二苯酮四酸二酐(BTDA))采用一步高温缩聚制备了3种新型聚酰亚胺NPI(3a～3c)。该类聚酰亚胺具有优异的溶解成膜性能,在室温可溶解于N-甲基-2-吡咯烷酮、N,N-二甲基乙酰胺、间甲酚等高沸点溶剂中,在加热时还能溶解于CHCl_3,CH_2Cl_2,THF等低沸点溶剂,并可通过其聚合物溶液浇铸得到柔韧的薄膜;所制聚酰亚胺薄膜具有优良的热性能,玻璃化转变温度(T_g)范围为262～303℃,在N_2中质量损失10%的温度超过523℃;具有优异的光学性能,所制薄膜还具有较浅的颜色和良好的光学透过性,在450 nm波长光下的透光率为69%～76%,截止波长为341～353 nm。     

四甲基联苯二胺及有机可溶聚酰亚胺的合成与性能

以对二甲苯为原料,通过溴代、偶合、硝化和还原反应成功合成了2,2′,5,5′-四甲基联苯-4,4′-二胺(TMBPDA)。TMBPDA分别与4,4’-双酚A型二醚二酐(BPADA)和4,4′-双酚AF型二醚二酐(FBDA)通过高温一步法缩聚生成聚酰亚胺PI-A和PI-AF。结果表明,两种聚酰亚胺不仅在N-甲基-2-吡咯烷酮(NMP),N,N-二甲基甲酰胺(DMAc)中展示出良好的有机可溶性,同时拥有优良热性能,由差示扫描量热仪(DSC)测得玻璃化转变温度(Tg)分别为251℃和255℃。此外,两种聚酰亚胺薄膜在可见光范围内具有良好的透明性,在450 nm处的透光率均超过了88%。     

具有极低熔体黏度的苯乙炔封端热固性聚酰亚胺树脂

为了开发适于树脂传递模塑(RTM)成型的低熔体黏度热固性聚酰亚胺树脂,采用2,2′,3,3′-三苯二醚四甲酸二酐(3,3′-HQDPA)和3,3′,4,4′-三苯二醚四甲酸二酐(4,4′-HQDPA)的混合物与3种不同的二胺单体合成了3种系列的苯乙炔封端的热固性聚酰亚胺树脂,其中二胺为4,4′-二氨基二苯醚(ODA),4,4’-二氨基-2,2’-双三氟甲基联苯(TFDB)和2-苯基-4,4′-二氨基二苯醚(p-ODA)。文中系统地研究了酰亚胺预聚物的结构和相对分子质量对预聚物的聚集态结构、熔体黏度及对固化后薄膜的热性能、力学性能的影响。研究结果表明,与ODA和TFDB不同,p-ODA的特殊化学结构使得由它合成的酰亚胺预聚物(相对分子质量为750)表现为无定形态,并在低温区具有极低的熔体黏度。它在200℃至280℃区间内任意温度恒温2 h后,熔体黏度都低于1 Pa·s,更适宜RTM成型。     

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.……     

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...     

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.     

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 ...