紫外光固化超支化聚酯丙烯酸酯/二氧化硅杂化材料的制备

以季戊四醇为"核",2,2-二羟甲基丙酸为支化单体,用逐步聚合的方法合成了不同代数超支化聚酯;将不同代数超支化聚酯分别与六亚甲基二异氰酸酯和丙烯酸羟乙酯半加成产物进行反应,得到一系列超支化聚酯丙烯酸酯低聚物。最后,将得到的超支化聚酯丙烯酸酯低聚物与改性纳米二氧化硅进行复合,得到可紫外光固化的超支化聚酯丙烯酸酯/二氧化硅杂化材料。对合成的超支化低聚物的结构用红外光谱、核磁共振谱和凝胶色谱进行表征。紫外光谱显示所有超支化低聚物在210 nm处有强的紫外吸收。超支化低聚物的玻璃化转变温度用差示扫描量热仪进行测量,结果显示温度范围为-68.68℃到-25.4℃。此外,对紫外光固化超支化聚酯丙烯酸酯低聚物的热性能用热重分析仪进行了表征。     

紫外光固化超支化聚酯丙烯酸酯/二氧化硅杂化材料的制备EI北大核心CSCD

以季戊四醇为"核",2,2-二羟甲基丙酸为支化单体,用逐步聚合的方法合成了不同代数超支化聚酯;将不同代数超支化聚酯分别与六亚甲基二异氰酸酯和丙烯酸羟乙酯半加成产物进行反应,得到一系列超支化聚酯丙烯酸酯低聚物。最后,将得到的超支化聚酯丙烯酸酯低聚物与改性纳米二氧化硅进行复合,得到可紫外光固化的超支化聚酯丙烯酸酯/二氧化硅杂化材料。对合成的超支化低聚物的结构用红外光谱、核磁共振谱和凝胶色谱进行表征。紫外光谱显示所有超支化低聚物在210 nm处有强的紫外吸收。超支化低聚物的玻璃化转变温度用差示扫描量热仪进行测量,结果显示温度范围为-68.68℃到-25.4℃。此外,对紫外光固化超支化聚酯丙烯酸酯低聚物的热性能用热重分析仪进行了表征。     

聚乙二醇二丙烯酸酯齐聚物的合成及其红外激光固化性能研究

使用3种方法合成了具有不同分子量的聚乙二醇二丙烯酸酯（PEGDA）齐聚物,包括：聚乙二醇（PEG）与丙烯酸反应,聚乙二醇与丙烯酰氯反应,聚乙二醇钠与丙烯酰氯反应,并在此基础上对3种合成方法进行比较。研究了聚乙二醇二丙烯酸酯齐聚物的红外激光固化反应,利用红外分析测定双键转化率,发现随着齐聚物分子量增大,激光固化后的双键转化率有所上升。     

溶胶-凝胶法制备纳米SiO2/丙烯酸酯预聚物

以3-氨丙基三乙氧基硅烷和三缩丙二醇双丙烯酸酯为原料,合成丙烯酸酯三乙氧基硅烷（APTP）,再用溶胶-凝胶法对其水解缩合制备纳米SiO2/丙烯酸酯预聚物（HAPTP）。对合成产物进行了表征,研究了APTP缩合水解对涂料及其固化膜性能的影响。结果表明,APTP经水解缩合后,有纳米SiO2生成。和APTP涂料相比,在相同的...     

紫外光固化有机硅的合成研究

以端氢硅油(PHMS)和1,6-已二醇二丙烯酸酯(HDDA)为原料在铂催化剂的作用下,用硅氢加成反应合成了两端带有双键的紫外光固化有机硅.采用红外光谱内标法测定了端氢硅油中活泼氢的转化率,讨论了反应温度、反应时间、反应物质的量比等因素对转化率的影响.确定了最佳反应条件:反应温度为90℃、反应时间为4h、1,6-已二醇二丙烯酸酯与端氢硅油的物质的量比为1.4:1.0.     

酚醛环氧丙烯酸酯光固化的动力学研究EI

以酚醛环氧丙烯酸酯为预聚体,季戊四醇三丙烯酸酯为交联剂,采用自由基聚合型光固化体系,测定了树脂膜的双键转化率、硬度及凝胶转化率等,研究了不同光敏引发体系的引发活性及光固化过程的各种影响因素及反应规律。结果表明,本文采用的三种引发体系的引发活性为安息香双甲醚(DMPA)>二苯酮/三乙醇胺(BP/TEOA)>二苯基二硫化物(DPDS)。固化速度随预聚体的增多而加快,而涂层的交联程度则主要和预聚体与交联剂的配比有关。     

高性能高硅烷含量硅丙复合乳液的研究

利用醇解反应，将γ-甲基丙烯酰氧基丙基三甲氧基硅烷中水解速度较快的甲氧基置换成水解速度较慢的乙氧基或异丙氧基，通过乳液共聚合成了高硅烷含量的硅丙复合乳液。用NMR，GC对硅烷单体进行了结构分析及转化率测试，并利用红外光谱对共降物进行了表征。研究了高有机硅含量对共聚物膜力学性能及吸水率的影响，证实了高含量硅烷组分能显著地提高丙烯酸酯乳液的物理性能。     

环氧丙烯酸酯涂料的UV固化研究

采用傅里叶红外光谱,对以γ-缩水甘油醚氧丙基三甲氧基硅烷与丙烯酸为主要原料所制备的低黏度环氧丙烯酸酯涂料的UV固化过程进行了定量分析。结果表明,环氧丙烯酸酯的UV固化反应是打开CC双键的自由基聚合反应,双键转化率的高低决定了涂膜的固化程度与硬度。随着固化时间的延长,环氧丙烯酸酯中CC双键的交联反应先快后慢,所得涂膜的硬度相应增加;固化时间为96s时,CC双键的转化率达到最高,涂膜的铅笔硬度为H;进一步延长固化时间,涂膜的硬度不再增加。     

辐射固化用聚硅氧烷的合成及表征

以端氢硅油（PHMS）和二缩三丙二醇二丙烯酸酯（TPGDA）为原料在铂催化剂的作用下,用硅氢加成反应合成了两端带有双键的辐射固化聚硅氧烷。采用红外光谱内标法测定了端氢硅油中活泼氢的转化率,通过正交试验确定了最佳反应条件：反应温度为100℃、反应时间为4h、二缩三丙二醇二丙烯酸酯与端氢硅油的物质的量比为1．2：1．0,反应催化剂氯铂酸为0．4％。产品经IR和HNMR表征,证明是所需产物。     

不饱和超支化聚酯的合成与表征

采用丙烯酸对端羟基超支化聚酯进行端基改性,使端基由羟基变成双键.并采用红外光谱和核磁氢谱对原料和产物的结构进行表征,证明得到了端基为双键的不饱和超支化聚酯,通过核磁氢谱的峰面积计算出基团的转化率在 90％以上.该不饱和超支化聚酯有望应用于自由基反应的交联剂和光固化材料.     

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 ...