PMDA与BDA型聚酰亚胺膜透气性能比较

聚酰亚胺是一类具有众多优良性能的气体分离膜材料。本文通过比较芳香族型聚酰亚胺（均苯四酸二酐（ＰＭＤＡ）型聚酰亚胺）与脂肪族型聚酰亚胺（丁烷四酸二酐（ＢＤＡ）型聚酰亚胺）对ＣＯ２和ＣＨ４的透气性能，初步探讨了二酐及二胺结构对聚酰亚胺膜透气行为的影响。     

可溶性共聚取代聚醚酰亚胺的H2／CH4和H2／N2的分离性能

本文合成了一系列可溶性共聚取代聚醚酰亚胺（ＨＱＤＥＡ／６ＦＤＡＤＭＭＤＡ），研究了它们的Ｈ２／ＣＨ４和Ｈ２／Ｎ２分离性能。随着６ＦＤＡ含量的增多，伴随着自由体积的增大，透Ｈ２系数呈线性增大，Ｈ２／ＣＨ４和Ｈ２／Ｎ２的分离系数均呈线性减小。当６ＦＤＡ含量占二酐组分的２０ｍｏｌ％和３０ｍｏｌ％时，共聚取代聚醚酰亚胺兼具有高的透Ｈ２性和Ｈ２／ＣＨ４及Ｈ２／Ｎ２选择性，是比较理想的Ｈ２分离与回收的膜材料。     

双醚二酐型聚醚酰亚胺的分子结构与透气性能

合成了一系列单环芳二胺型聚醚酰亚胺，研究了它们对Ｈ２、Ｏ２和Ｎ２３种气体的透过性能。这类双醚二酐（ＨＱＤＥＡ）型聚醚酰亚胺的分子结构对其透气性和透气选择性有很大的影响，随着二胺单体分子中甲基的增多，聚醚酰亚胺的透气性增大，透气选择性减小；由３，５－二氨基苯甲酸合成的ＨＱＥＤＡ－ＤＡＢ具有较高的透Ｈ２系数和很高的Ｈ２／Ｎ２分离系数。     

二胺改性BPDA－ODA型聚酰亚胺的H_2／N_2分离性能

本文合成了一系列二胺改性的ＢＰＤＡ－ＯＤＡ型共聚酰亚胺膜，改性聚酰亚胺与未改性的ＢＰＤＡ－ＯＤＡ相比，透气性得到了明显的改善，改善的程度与第二种二胺单体的结构和用量有关。３０℃时，在ＢＰＤＡ－ＯＤＡ中加入２０ｍｏｌ％三甲基间苯二胺（３ＭＰＤＡ）或四甲基对苯二胺（４ＭＰＤＡ）时，共聚酰亚胺ＢＰＤＡ－ＯＤＡ／３ＭＰＤＡ（８０／２０）或ＢＰＤＡ－ＯＤＡ／４ＭＰＤＡ（８０／２０）的透Ｈ２系数和Ｈ２／Ｎ２分离系数分别大于６．５ｂａｒｒｅｒ和１６０，是比较好的气体分离膜材料。     

改性双来亚酰亚胺树脂的研究

合成了２，２′－亚甲基－二（４－甲基－６－烯丙基）苯酚，和它增韧二苯甲烷型双马来酰亚胺树脂，对改性双马亚酰亚胺预聚物的凝胶化时间、ＤＳＣ分析和ＦＴ－ＩＲ分析的研究，得到了改性双马亚酰胺树脂体系的固化条件来１８０℃／１ｈ＋２００℃／２ｈ＋２５０℃４／ｈ；热重分析法研究了双马亚酰亚胺树脂体系的热分解反应动力学，得出体系的的热分解反应活化能为２７４．４ｋＪ／ｍｏｌ；改性双马来酰亚胺树脂体系常弯曲强度为１     

聚异酰亚胺

聚异酰亚胺赵育（化工部成都有机硅研究中心）１．前言聚酰亚胺具有热膨胀系数小，机械性能好、电性能优良、耐温等级高等许多优良性能，所以是电子、宇航、通讯等尖端技术领域中很有发展前途的重要材料。使聚酰亚胺应用受到限制的重要原因有两个：其一，它是一种不溶难熔...     

某些氨羧络合剂对黑白药液稳定性的影响

研究了乙二胺四乙酸（ＥＤＴＡ）、丙二胺四乙酸（ＰＤＴＡ）、二乙三胺五乙酸（ＤＴＰＡ）和三乙四胺六乙酸（ＴＴＨＡ）对黑白显影液稳定性的影响。结果表明，加入４种氨羧络合剂后，显影液的稳定性顺序为ＰＤＴＡ＞ＥＤＴＡ＞ＤＴＰＡ＞ＴＴＨＡ；用Ｐｂ２＋－双硫腙／氯仿反萃取法测定氨羧络合剂的量时发现，络合剂的消耗对显影液稳定性有很大作用     

二胺改性BPDA—ODA型聚酰亚胺的H2／N2分离性能

本文合成了一系列二胺改性的ＢＰＤＡ－ＯＤＡ型共聚酰亚胺膜，改性聚酰亚胺与未改性的ＢＰＤＡ－ＯＤＡ相比，透气性得到了明显的改善，改善的程度与第二种二胺单体的结构和用量有关。３０℃时，在ＢＰＤＡ－ＯＤＡ中加入２０ｍｏｌ％三甲基间苯二胺（３ＭＰＤＡ）或四甲基对苯二胺（４ＭＰＤＡ）时，共聚酰亚胺ＢＰＤＡ－ＯＤＡ／３ＭＰＤＡ（８０／２０）或ＢＰＤＡ－ＯＤＡ／４ＭＰＤＡ（８０／２０）的透Ｈ２系数和Ｈ２／Ｎ２分     

几种共聚醚酰亚胺的H2／N2分离性能

合成了一系列双醚二酐（ＨＱＤＥＡ）型共聚醚酰亚胺，研究了它们的Ｈ２／Ｎ２分离性能。刚性二胺单体的引入可明显降低聚醚酰亚胺的链段活动性，改善Ｈ２／Ｎ２分离性能。３０℃时，ＨＱＤＥＡ－ＭＤＡ／ＤＡＢ（８０／２０）和ＨＱＤＥＡ－ＭＤＡ／ＴＤＡ（８０／２０）的透Ｈ２系数分别比均聚物ＨＱＤＥＡ－ＭＤＡ高２４％和１５％，Ｈ２／Ｎ２分离系数分别比ＨＱＤＥＡ－ＭＤＡ高９％和３０％。     

共缩聚型可溶性聚酰亚胺的合成与性能研究(3)

以４,４′－二（４－氨基苯氧基）二苯砜及４,４′－二氨基二苯醚或４,４′－二氨基二苯甲烷为共缩聚二胺单体与二苯醚３,３′,４,４′－四甲酸二酐缩聚并经化学亚胺化合成了共缩聚型聚酰亚胺。当共缩聚二胺单体中４,４′－二（４－氨基苯氧基）二苯砜／４,４′－二氨基二苯甲烷和４,４′－二（４－氨基苯氧基）二苯砜／４,４′－二氨基二苯醚的摩尔比分别为１０∶０～５∶５及１０∶０～３∶７时,所得聚酰亚胺可溶于强极性溶剂。可溶性聚酰亚胺的玻璃化转变温度（Ｔｇ）在２５５～２６５℃,并随结构中４,４′－二（４－氨基苯氧基）二苯砜的摩尔比上升而略有下降。聚酰亚胺在Ｎ２中的热降解起始温度在５５５～５９０℃,并且与二胺单体的结构及比例基本无关。     

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 ...