水下凝胶聚氨酯的制备及其性能研究

研究了水下凝胶聚氨酯的合成、封闭以及在水中解封闭工艺条件,实验结果表明:在亲水性聚醚多元醇中添加10%的油溶性聚醚多元醇,可显著提高水下凝胶聚氨酯的粘接强度。采用添加了油溶性聚醚多元醇的水溶性聚醚多元醇在85℃与甲苯二异氰酸酯预聚,反应时间180min,制得水溶性聚氨酯,对制取的水溶性聚氨酯活性基团进行封闭,以苯酚为封闭剂,氰酚摩尔比为1∶1.2,二月桂酸二丁基锡为催化剂,其用量为0.3%,产品置于热水中解封,凝胶效果良好。     

水性聚氨酯固化剂的研究进展

介绍了用于合成聚氨酯固化剂的异氰酸酯类型,综述了聚氨酯固化剂亲水性改性方法及封闭型水性聚氨酯固化剂的封闭机理、封闭剂类型,并指出了水性聚氨酯固化剂研究的不足和未来的发展趋势。     

封闭型无溶剂聚氨酯的研究进展

传统溶剂型聚氨酯(PU)的使用容易造成环境污染,阻碍了PU在功能性膜、涂饰剂、发泡材料等领域的广泛应用。封闭型无溶剂聚氨酯(SFPU)具有绿色环保、低能耗、高稳定性、操作简单等优势,成为近年来PU领域的研究热点,尤其是活性可控的SFPU能够实现高效封闭与解封闭,促进了PU材料的进一步发展。然而,由于封闭剂种类及结构的差异,形成的封闭型SFPU预聚体的解封闭温度波动大、易黄变,此外,解封时小分子封闭剂的逸出破坏了产物结构的规整性,降低了其力学性能。因此,近年来除研究单体对封闭型SFPU理化性能的影响外,研究者们主要在封闭剂的选择方面不断进行尝试,并取得了相关成果,在提高封闭型SFPU材料稳定性的同时有效降低了其解封闭温度。目前,封闭型SFPU在120℃下可实现完全解封闭。现有的常用封闭剂主要为醇类、酚类、肟类、胺和酰胺类、活泼亚甲基类、吡唑和三唑类、亚硫酸氢盐类等。在这些封闭剂中,醇类结构的封闭剂使用最早,封闭的预聚体具有较低的活性和较高的解封闭温度,赋予材料极好的稳定性;尽管肟类封闭剂在较低的解封闭温度下能够释放活性异氰酸酯基,有助于重新裸露出的异氰酸酯基与扩链剂进行扩链,但其耐黄变性较差;毒性较小的吡唑和三唑类封闭剂具有含氮五元环的结构,产物不易黄变。封闭型SFPU起初采用直接封闭异氰酸酯单体的方法制备,但该法的扩链效果较差、成膜性能差。近几年的研究工作采用封闭SFPU预聚体的方法,即先合成SFPU预聚体,再进一步对预聚体进行封闭,确保了封闭型SFPU的高分子量和良好的成膜性。本文对封闭型PU的研究进展进行了综述,包括封闭型溶剂PU、封闭型水性聚氨酯(WPU)和封闭型SFPU这三类工艺,并讨论了封闭型PU的类型与合成、常用封闭剂、封闭-解封闭反应机理、解封闭温度的影响因素、解封闭温度的测定方法。最后总结了目前封闭型SFPU的优点和不足之处,指出解决其解封闭时封闭剂逸出、解封闭温度较高和黏度较大三大难点是该项技术应用进程中的关键。     

咪唑封闭水性聚氨酯复鞣剂的制备及表征

通过分子设计,以咪唑为封闭剂,1,6-己二异氰酸酯（HDI）、二羟甲基丙酸（DMPA）、2,2-二（4-羟基苯基）丙烷、聚酯二醇为原料制备出咪唑封闭水性聚氨酯复鞣剂（BPU）。用FT-IR、动态激光光散射（DLS）、TEM、TGA、DSC分别对BPU分子结构、乳胶粒形态及热性能进行了表征,分析了BPU复鞣剂的分子作用基础。结果表明产物分子结构中出现了羧基、咪唑环和聚氨酯结构;乳胶粒呈较为规则的、具有核壳结构的球形,粒径的多分散性是BPU具有良好选择填充性的微观原因。TGA和DSC分析显示BPU耐热性较高并随封闭率增加而略有降低;BPU解封温度范围为107.5～124.5℃,峰值为115.1℃;应用过程中BPU解封程度极低,利于助染性能的提高。     

咪唑封闭聚氨酯的制备及在纸张增强中的应用

以咪唑为封闭剂,1,6-己二异氰酸酯(HDI)、二羟甲基丙酸(DMPA)、双酚A、聚酯二醇为原料制备出阴离子封闭聚氨酯(ABPU)。用傅里叶变换红外光谱(FT-IR)、动态激光光散射(DLS)、透射电镜(TEM)分别对ABPU分子结构及乳胶粒形态进行了表征,研究了ABPU封闭率对纸张力学性能的影响。结果表明,增加ABPU封闭率,能明显提高纸张的强度指标,尤其是湿拉伸指数。产物分子结构中出现了羧基、咪唑环和聚氨酯结构;乳胶粒径与羧基含量密切相关,乳胶粒呈不规则的、具有核壳结构的球形。     

羧基丁苯胶/封闭聚氨酯纸基复合材料的制备及防水增强作用

以咪唑为端异氰酸酯基封闭剂,制备封闭聚氨酯预聚体,然后以羧基丁苯胶水溶液进行反相乳化,并加入氮丙啶,制得系列水分散羧基丁苯胶/封闭聚氨酯植物纤维防水增强剂(XSBRL/BPU)。XSBRL/BPU的综合性能与BPU封闭率、羧基丁苯胶/封闭聚氨酯比例、交联剂氮丙啶含量及复合乳液的添加量有关。当封闭率BR=10%、m(BPU)/m(XSBRL)=2/1、ω(氮丙啶)=2%、ω(乳液)=8%时,纸基复合材料具有良好防水性能、黏合强度和机械性能,其中,耐折度为158次、施胶度为180s、干抗张指数为63.4N.m.g-1、湿抗张指数为33.8N.m2g-1、湿强度为53.3%。     

铝及铝合金阳极氧化膜常温封闭技术

为提高铝及其合金氧化膜的耐蚀性和耐污能力,必须对膜作常温耐封闭处理。为此,研究了在GA-93（A）封闭剂中添加环己酮,减少缓冲剂的用量,以提高铝及其合金氧化膜常温封闭质量的方法。讨论了封闭材料表面的影响,结果表明,封闭后的材料表面质量符合ISO3210要求。用本封闭剂处理的铝材料表面光滑。     

咪唑系水性封闭型聚异氰酸酯交联剂的制备与性能

以异佛尔酮二异氰酸酯(IPDI)和2,2-二羟甲基丙酸(DMPA)制备亲水性的异氰酸酯(NCO)封端的线型预聚体,再以预聚体与三羟甲基丙烷(TMP)反应合成支化结构中间体,最后以8种咪唑(IDZ)衍生物分别对残留的NCO基团进行封闭,制得一系列水性封闭型聚异氰酸酯交联剂。以傅里叶变换红外光谱表征了交联剂的结构,以热分析法着重研究了封闭剂的结构对交联剂解封温度的影响,结果表明交联剂的最低解封温度为100℃;稳定性研究表明交联剂在水性聚氨酯乳液中有较好的力学稳定性和适用稳定性。     

铝阳极氧化膜中温封闭剂的研制

研制了一种ＭＳ 5 0中温封闭剂 ,它克服了一般低温封闭剂的管理难、不能用于染色料封闭、速度慢的缺陷及沸水对水质要求高、能耗大、易起灰、时间长的缺陷 ,具有较强的实用性。1　试　验铝阳极氧化试验 :选取 1ｄｍ2 的 6 0 6 3铝合金 ,常规预处理后进行硫酸阳极氧化 ,膜厚 10～ 2 5 μｍ ;染色 :按染料要求进行 ;封闭试验 :选取意大利、日本等二种中温封闭剂作比较 ;封闭液成分的测定 :Ｎｉ2 + 按常规络合滴定方法分析 ;质量检测 :将已封闭铝材样品按染色分别滴红或蓝的青年牌墨水 ,1ｍｉｎ后水洗 ,观察染色 ,颜色越浅越好。2　配方筛选经…     

封端异氰酸酯研究进展（Ⅰ）

封端异氰酸酯是制备单组分聚氨酯涂料和粘合剂的重要原料之一，用于异氰酸酯封端的封闭剂种类很多，本文重点对酚类封端异氰酸酯的解封、醇解、胺解等进行了研究。     

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.     

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...     

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.     

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.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.