异氰尿酸三(2—羟乙基)酯在高分子合成中的应用

异氰尿酸三(-2羟乙基)酯(THEIC)是(?)六十年代初首先在美国研制成功的。近十多年来,美国、日本等国使用THEIC合成了聚酯、聚酯-酰亚胺、聚酯-酰胺-酰亚胺、聚氨酯等。并制得了涂料、漆包线漆、粘合剂、     

煤沥青粉填充氯醋/聚氨酯复合材料的热特性

采用差示扫描量热分析(DSC)、热重分析(TG)研究了煤沥青粉填充氯醋/聚氨酯复合材料的玻璃化转变温度、粘流温度及热分解特性,在氮气氛下以不同升温速率讨论并计算得热解动力学相关参数及热解速率经验方程式。结果表明,煤沥青粉填充氯醋/聚氨酯弹性体复合材料的玻璃化温度为-46℃,粘流温度为145℃,其耐热特性与氯醋/聚氨酯材料基本一致。该复合材料热降解分两阶段,活化能E为(97.9±1.1)kJ/mol(、229.8±3.9)kJ/mol,反应级数n为1.2和0.9。     

从专利谈聚酰亚胺的发展动向

在250℃以上连续使用几年也不热变形、热老化,仍能保持材料特性的聚酰亚胺类耐热高分子材料,引起了产业界各方面的关注.聚酰亚胺类树脂现已广泛应用于 LSI、微器件、电子线路基板、航天机器内装机械零件、耐热电绝缘薄膜、镀铜膜层压板、油压机的密封材料、漆包线漆、飞机电气装备零件、导弹头用复合材料,及飞机的一次结构材料等方面。它是实现电子机器、器件的     

漆包线脱漆剂的研制和应用

一、前言在电器工业、电机工业以及其它工业上经常会用到漆包线,在使用过程中必须将漆包线端头的绝缘漆彻底清除才能焊接。除去绝缘漆的方法很多。有人工刮漆、机械刮漆以及使用脱漆剂,漆包线的漆膜具有高的机械强度和耐溶剂性。人工刮漆速度慢,耗     

酯交换法合成聚氨酯的预聚反应动力学

熔融酯交换法是合成聚氨酯材料的一种全新工艺方法。文中基于熔融酯交换法,并根据其特点,对预聚动力学进行了研究。利用液相色谱法研究了1,6-六亚甲基二氨基甲酸甲酯(HDU)与聚乙二醇(PEG)在110℃,115℃,120℃和125℃熔融酯交换合成聚氨酯的预聚表观反应动力学;计算了这4个温度的正逆反应速率常数与平衡常数;按照Arrhenius计算了该反应的表观活化能为99.62 k J/mol,指前因子为2.51×1012m L/(mol·min);按照Van’t Hoff方程计算了该反应的表观反应焓为101.34 k J/mol。     

热塑性聚氨酯改性环氧树脂的制备与微观特性表征

为了获得一种柔性环氧树脂,选用聚四氢呋喃醚二醇(PTMEG)和二苯基甲烷二异氰酸酯(MDI)制得的热塑性聚氨酯弹性体(TPU)预聚体对E-51型环氧树脂(EP)进行改性,通过拉伸强度、断裂伸长率和弯曲强度等力学性能测试方法得到聚氨酯改性环氧树脂中环氧树脂、TPU预聚体和固化剂的最佳掺配比例。借助红外光谱(FTIR)、差示扫描量热仪(DSC)、热失重(TG)与扫描电镜(SEM)表征聚氨酯改性环氧树脂的微观特性。结果表明：当聚氨酯预聚体改性EP的适宜反应温度为80℃、聚氨酯预聚体的掺量为20%、A和B组分的最优掺配比例为2∶1时,改性体系的力学性能最佳,表干时间为3.5 h,完全干燥时间为9 h,抗拉强度为53.1 MPa,断裂伸长率为153.34%,弯曲强度为48.14 MPa,弯曲变形为13.61 mm,黏结强度为1.89 MPa,T_5%和T_10%分别为386.4℃、437.2℃,玻璃化转变温度为-27.9℃。通过FTIR与SEM对其改性机理进行分析发现,聚氨酯改性EP达到提高材料韧性的效果,且改性过程属于化学改性范畴。本研究可为合理地选择环...     

基于网络结构设计制备宽温域高阻尼聚氨酯弹性体

从网络结构角度出发,设计以聚乙二醇单甲醚(mPEG)与甲苯2,4-二异氰酸酯(TDI)反应所制得预聚体为悬挂链,聚酯二元醇和TDI反应制得预聚体为弹性链,超支化H201作为交联扩链剂制备无规网络结构的聚氨酯弹性体。采用动态力学分析仪、原子力显微镜以及正电子湮没寿命谱等表征其结构与性能,从自由体积、微相分离、氢键作用等结构与性能之间的关系深入探讨聚氨酯宽温域高阻尼机理。研究结果表明,随着悬挂链含量增加,R值(n(-NCO)/n(-OH))减小,聚氨酯的微相分离程度降低,相容性增加,氢键作用增强,自由体积增大,聚氨酯的有效阻尼(tanδ≥0.3)温域可达175℃(-60~115℃),为一种基于网络结构设计的新型聚氨酯阻尼材料。     

水性聚氨酯乳液的无溶剂法制备及乳化工艺研究

以异佛尔酮二异氰酸酯(IPDI)、新戊二醇己二酸酯二元醇(NPGA-1500)为主要原料,以三乙胺(TEA)为中和剂,以乙二胺(EDA)为扩链剂,通过无溶剂法制备了水性聚氨酯乳液。研究了搅拌转速、三乙胺中和时间、乳化温度、加水速度、乙二胺扩链方式等因素对无溶剂型水性聚氨酯乳液性能的影响。结果表明,在3 000r/min转速、5min中和时间、40℃乳化温度、50mL/min加水速度、乙二胺后扩链的条件下,可制得粒径为(180±19)nm,且稳定性和涂膜力学性好的无溶剂型水性聚氨酯乳液。     

重防蚀涂装体系在广岛和重庆的自然环境试验

大量的工业设施受酸雨和海洋腐蚀较为严重,中国重庆和日本广岛的自然环境具有一定的特殊性和代表性,针对4种用途13种涂装工艺的重防蚀涂装体系进行了耐酸雨和海洋严酷环境腐蚀规律的自然环境对比试验.结果表明:在重庆的涂层腐蚀均比广岛严重;所有暴露3年的试样,在重庆的划痕单侧最大腐蚀宽度几乎都超过3 mm,而在广岛几乎都在3 mm以下;即使按耐强腐蚀环境设计的重防蚀涂装试样,在重庆的腐蚀也比较严重.重庆的自然环境腐蚀严酷度等级比广岛高1个等级,在酸雨地区对钢铁具有较好保护作用的涂装体系(防蚀性和装饰性保护层)有两种:(1)热浸Zn→环氧底漆→聚氨酯面漆;(2) 厚膜无机富锌漆→喷涂层→环氧底漆→环氧底漆→聚氨酯中涂漆→聚氨酯面漆.     

有机硅改性聚氨酯的性能研究

含硅聚醚与二异氰酸酯(TDI)反应,氨丙基三甲氧基硅烷进行封端,制得一种有机硅改性聚氨酯,通过红外光谱表征了聚氨酯的结构。探讨了各种因素对聚氨酯成膜物性能的影响。研究结果表明:R值为1.5,反应温度为35℃～40℃,自制硅醚:N210的比值为1∶7,封端率为10%时,所得的含硅聚醚聚氨酯的性能较好。     

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.……     

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.     

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 ...