高分子表面活性剂对超声辐照下苯乙烯乳液聚合的影响

在超声辐照引发苯乙烯乳液聚合中加入一种新型的以羧甲基纤维素为基础的高分子表面活性剂(CMC—A9)，讨论了高分子表面活性剂对反应动力学的影响。实验表明，超声辐照下初级自由基并非由通常认为的高分子表面活性剂产生，而是十二烷基硫酸钠在超声辐照下断裂，产生自由基。通过对反应动力学的研究，发现超声辐照下乳液聚合机理不同于常规乳液聚合，聚合反应过程只有两个阶段，即加速期和减速期，不存在恒速期。加入CMC—A9高分子表面活性剂，可以在较短的时间内和较低的超声功率下达到较高的单体转化率。     

超声辐照引发MMA微乳液聚合产物结构表征

表征了超声辐照引发ＭＭＡ微乳液聚合产物的结构,透射电镜观察结果表明,超声辐照引发ＭＭＡ微乳液聚合得到的ＰＭＭＡ乳胶粒平均粒径为３６．５ｎｍ。粒径分布窄;粘度法测试表明得到的ＰＭＭＡ分子量约为５百万;红外光谱法和核磁共振氢谱法测试结果表明,超声辐照引发微乳液聚合得到的ＰＭＭＡ以间同立构为主。     

超声波无皂乳液制备BA/AM/纳米SiO2复合材料

将超声波辐照技术引入到聚合物纳米材料的制备过程,通过超声产生的分散、活化及引发等作用实现纳米粒子分散的同时进行无皂乳液聚合,制备了丙烯酸丁酯(BA)／丙烯酰胺(AM)／纳米SiO2复合材料。实验结果表明．采用经丙烯酸丁酯表面改性后的纳米SiO2粒子．生成的乳液分散稳定性好。FT-IR及TEM证实了聚合物对纳米粒子的包裹。研究了超声波强度、超声辐照时间、单体配比等因素对单体转化率和聚合速率的影响。结果表明,提高超声波强度,延长超声辐照时间以及提高丙烯酰胺在单体配比中的含量．均能提高单体转化率和聚合反应速度。     

用可聚合表面活性剂在超声辐照下乳液聚合制备聚苯乙烯纳米粒子

合成了一种离子型可聚合表面活性剂马来酸酐衍生物磺酸钠(M12),它既可作为乳化剂又能充当引发剂,在超声辐照下乳液聚合制备了聚苯乙烯纳米粒子。产物的红外光谱分析表明,可聚合表面活性剂与苯乙烯发生了共聚,随M12加入量的增加,M12共聚组成提高。用凝胶渗透色谱、透射电镜对超声辐照乳液聚合产物的分子量、乳胶粒形貌和大小进行了表征,发现得到的是高分子量(>106)的聚苯乙烯纳米粒子,粒径为15nm～45nm,分布较窄。对该聚合反应影响因素的研究结果表明,表面活性剂M12浓度增加、超声波输出功率增加、温度升高、加快氮气流速和单体浓度减少都有利于提高单体转化率。     

改性水性丙烯酸酯胶黏剂的研究进展

目的 综述近年来水性丙烯酸酯胶黏剂改性方法和合成技术的国内外研究进展,以期为水性丙烯酸酯胶黏剂的进一步研究及在包装材料领域的应用提供参考。方法 介绍丙烯酸酯胶黏剂的组成,综述水性丙烯酸酯胶黏剂的主要改性方法,阐述种子乳液聚合、反相乳液聚合、核壳乳液聚合、微乳液聚合、细乳液聚合、无皂乳液聚合、超声辐照乳液聚合、乳液互穿聚合物网络和Pickering乳液聚合等技术合成不同种类和性能丙烯酸酯胶黏剂的相关研究,概述丙烯酸酯胶黏剂在包装、纺织等领域的具体用途。结论 对水性丙烯酸酯胶黏剂的未来趋势和研究前景进行了展望,将多重改性方法有机结合,开发高性能水性丙烯酸酯胶黏剂,合成并应用新型生物基胶黏剂、特种功能性胶黏剂、低成本绿色水性丙烯酸酯胶黏剂。     

可见光乳液聚合制备OMMT/聚甲基丙烯酸甲酯纳米复合乳液及表征

结合可见光固化技术和乳液聚合技术应用于纳米级复合乳液的制备。选用甲基丙烯酸甲酯为单体，在可见光发光二极管最大发射波长为430nm(LED@430nm)的光源辐照下，以荧光增白剂和二苯基碘鎓六氟磷酸盐组成的二元光引发体系制备了有机改性蒙脱土(OMMT)/聚甲基丙烯酸甲酯纳米复合乳液。结果表明：高浓度十六烷基三甲基溴化铵改性所得OMMT在相同反应条件下有效地促进了单体的转化率；更重要的是，可见光引发乳液聚合反应有效地提高了纳米复合乳液传统制备方法的效率，在可见光LED光源辐照下，仅需30min即可高效制备纳米级复合乳液。     

频率对声致羟自由基形成的影响

本文用声化学效率的概念，报道了频率对声致羟自由基形成的影响，在氮气或空气环境中，高频超声辐照所致ＯＨ的化学产率比低频超声辐照时高。     

超声辐照对PP/EPDM共混物在加工过程中微相结构的影响

研究了超声辐照对聚丙烯／三元乙丙橡胶(PP／EPDM)共混物挤出过程及二次加工中微相结构的影响．结果表明随超声功率的增加EPDM相的比表面积增大，界面作用增强．超声辐照使EPDM在PP中形成的良好的分散效果在经过热压二次成型后仍大部分得以保持．动态流变分析显示超声振动使PP／EPDM共混物的内部结构变得更加均匀．Palierne乳液模型计算结果表明，超声辐照使共混物中两相的界面张力降低，这说明超声辐照使两相间形成了良好的界面结构和牢固的界面作用，有效地阻止了EPDM液滴在共混过程以及随后的热压成型加工过程中的合并．     

超声辐照对高密度聚乙烯热稳定性及结晶性的影响

采用自行设计的超声辐照装置,研究了不同超声辐照功率(0 W,100 W,200 W,300 W,400 W)及不同超声辐照时间(0 min,5 min,10 min,15 min)对高密度聚乙烯(HDPE)的热稳定性、结晶性及流变性能的影响。通过同步热分析仪分析得出超声辐照功率越大,辐照时间越长,HDPE的热稳定性能越好,400 W下辐照15 min的HDPE 5%失重温度比未辐照的HDPE 5%失重温度提高了近26%;通过X射线衍射及差示扫描量热分析得出超声辐照会有细化晶粒的作用,辐照功率和辐照时间对结晶度均有影响且在功率200 W辐照5 min时,结晶度达到最大;通过旋转流变仪表征得出经超声辐照处理的HDPE的剪切黏度都有所降低,在400 W的超声功率下辐照10 min时,剪切黏度达到最低,利于加工成型。     

微波辐照辅助核/壳型聚硅氧烷/聚丙烯酸酯复合乳液的制备与表征

微波辐照乳液聚合技术具有产率高、节能省时等优点.本工作利用微波辐照,采用半连续种子乳液聚合法制备了具有明显核壳结构的聚硅氧烷/聚丙烯酸酯复合乳液;利用傅里叶变换红外光谱、粒度分析、核磁分析、透射电镜、热重分析等技术手段对产物进行了系统化表征,研究了偶联剂(γ-甲基丙烯酰氧基丙基三异丙氧基硅氧烷,C-1757)的用量对乳液聚合和复合胶膜性能的影响.结果表明:复合乳胶粒的平均粒径均小于100 nm,具有明显的核/壳结构;随着偶联剂用量的增加,复合乳胶粒粒径增大,分布变窄,制备的复合胶膜吸水率明显降低,力学性能和热稳定性显著提高.     

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.     

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.     

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.……     

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.     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

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