可溶性双马来酰亚胺树脂的研制及其耐热性研究

报导研制具有良好溶液性质的４，４＇－二氨基二苯甲烷双马来酰亚胺（ＢＭＩ）树脂体系的新方法。它是由ＢＭＩ、４，４＇－二氨基二苯甲烷（ＭＤＡ）、电子富集物Ｂ三元共混物预聚而成。这种预聚物可用丙酮作溶剂制造预浸料。重点研究了该树脂的百分配比与其溶解性和耐热性的关系。     

改性双马来酰亚胺/T300复合材料研究Ⅰ.改性双马来酰亚胺基体树脂的制备

研制了具有良好溶液性质的双马来酰亚胺树脂体系的新方法。该树脂由４，４′－二氨基二苯甲烷双马来酰亚胺，４，４′－二氨基二苯甲烷，改性物Ｂ三元共混物预聚而成。研究结果表明，预聚体在丙酮中具有良好的溶解性，预聚体固化后具有较高的耐热稳定性，可以作为高性能复合材料的候选基体树脂。     

改性双马来酰亚胺/T300复合材料研究:I.改性双马来酰亚…EI

研制了具有良好溶液性质的双马来酰胺树脂体系的新方法，该树脂由４，４′二氨基二苯甲烷双马来酰亚胺，４，４′－二氨基二苯甲烷，改性物Ｂ三元共混物预聚而成，研究结果表明，预聚体在丙酮中具有良好的溶解性，预聚体固化后具有较高的耐热稳定性，可以作为高性能复合材料的候选基体树脂。     

共缩聚醚酯聚酰胺亚胺的合成和性能研究

用对－氨基苯甲酸酯封端的聚（四次亚甲基）醚（ＡＰＴＭＯ），４，４－二氨基二苯酰胺（ＤＡＢＡ）及均苯四甲酸二酐（ＰＭＤＡ），利用溶液聚两步法合成了一系列不同硬段含量的共缩聚醚酯聚酰胺亚胺。用动态力学分析（ＤＭＡ）、示差扫描量热（ＤＳＣ）研究了样品的热性能和相态结构，用热重分析（ＴＧＡ）和应力－应变试验测定了材料的热稳定性能和力学性能。结果表明，共缩聚醚酯聚酰胺亚胺具有两相结构，有良好的力学性能和热稳     

可溶性聚酰亚胺的合成与性能研究

采用“柔顺性”二胺单体４，４＇－二（４－氨基苯氧基）二苯砜与二氨基二苯砜及二苯甲酮四甲酸酐进行共缩聚并在高温溶液亚胺化合成了可溶于ＮＭＰ、ＤＭＡｃ、ＤＭＦ等强极性溶剂的可溶性聚酰亚胺，并发现在本研究体系中，单纯提高分子链柔顺性并不能很好地提高ＰＩ的可溶性，必须结合共缩聚方法以破坏分子链规整性，所得ＰＩ只有在４，４’－二（４－氨基苯氧基）二苯砜与二氨基二苯砜的摩尔比在３：７～６：４时才可溶。所得可溶性ＰＩ的特性粘度为０．２１～０．３８ｄｌ／ｇ（ＮＭＰ为溶剂，Ｔ＝３０℃），以ＤＳＣ测得的玻璃化转变温度在２５０～２９０℃，氮气中热分解温度在５００℃以上。     

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     

烯丙基酚氧树脂改性BMI的研究

介绍３种烯丙基酚氧树脂改性ＢＭＩ体系，详细研究了这些体系的溶解性，反应性，耐热性，结果表明，烯丙基酚氧树脂／Ｏ，Ｏ‘－二烯丙基双酚Ａ／ＢＭＩ体系具有良好的反应性；预聚物可溶于普通溶剂丙酮中，固化物具有良好的韧性和耐热性，其ＨＤＴ〉２８０℃，Ｔｇ〉３００℃，冲埚强度大于１５ｋＪ／ｍ＾２。     

改性双马来酰亚胺树脂的研究

合成了２，２′－亚甲基－二（４－甲基－６－烯丙基）苯酚，用它增韧二苯甲烷型双马来酰亚胺树脂，对改性双马来酰亚胺预聚物的凝胶化时间、ＤＳＣ分析和ＦＴ－ＩＲ分析的研究，得到了改性双马来酰亚胺树脂体系的固化条件为１８０℃／１ｈ＋２００℃／２ｈ＋２５０℃／４ｈ；热重分析法研究了双马来酰亚胺树脂体系的热分解反应动力学，得出体系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温弯曲强度为１２４ＭＰａ，弯曲模量为３７７４．６ＭＰａ，２５０℃下弯曲强度保留６９％，弯曲模量保留７８％。     

主链含长柔性链的聚酰亚胺的合成与性能研究

以α,ω－二（４－氨基苯氧基）ｎ烷与六氟叉丙基二－（３,４－邻葳二甲酸酐）缩聚并经化学亚胺化合成了主链含长柔性链的聚酰亚胺。该类聚酰亚胺在ＤＭＡ、ＤＭＦ、ＮＭＰ、ＴＨＦ、间甲酚氯仿中有很好的溶解性,且与柔性链的长度无关。     

双马／二元胺／环氧体系的组成对性能的影响

以普通的４，４－二氨基二苯甲烷双马来酰亚胺为基础，用二元胺和环氧树脂进行改性。着重研究了不同结构的二元胺和环氧树脂及其复合材料性能的影响，结果表明，ＤＤＳ必性体系的生优于ＤＤＥ改性体系，但其预物丙酮溶解性差于ＤＤＥ预聚物。ＢＭＩ／二元胺摩尔比高的改性树脂耐热性高，但韧性低，丙酮溶解性差。不同结构的环改性以树脂耐热性相差不大，但环氧的结构对双马改性环氧树脂的耐热性、韧性影响较大。环氧用量增加，工艺改     

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 ...