当前合成宝石国际市场的发展动态

合成宝石指与天然宝石物理化学性质相同的人造合成宝石.目前,市场上常见的合成宝石有:合成钻石、合成红宝石、合成蓝宝石、合成祖母绿、合成尖晶石、合成金红石、合成欧泊、合成紫晶等.常见的制作方法有焰熔法、熔融法、水热法和助熔剂熔化生长法,其中,以水热法生长工艺最为复杂,合成出来的晶体在外观方面更接近优质天然宝石,因而在国际市场上更受消费者欢迎,价格也相对较高.     

离子液体的合成研究进展

综述了离子液体的合成研究进展,具体的合成方法包括：传统的一步和两步合成法;新型的超声波辅助合成、微波辅助合成、电化学合成和液液萃取法。对一步和两步合成法进行分析和比较;对新型超声波辅助、微波辅助、电化学合成和液液萃取等合成方法的工艺流程进行分析,发现超声波辅助、微波辅助可以大幅度缩短合成时间,电化学合成和液液萃取法可以得到高纯度的离子液体。     

中孔沸石分子筛合成研究进展

对当前国际国内中孔分子筛的合成研究状况进行了综述 ,重点介绍了分子筛合成的新方法、模板剂的作用、合成机理、影响合成的因素、元素掺杂等合成中的关键问题 ,并展望了分子筛合成的发展趋势。     

高岭土合成Y型分子筛研究进展

综述高岭土合成Y型分子筛研究进展,分别从原位合成、纳米分子筛、高硅分子筛和其他合成方法进行评述,并分析各种合成方法的优缺点。原位合成Y型分子筛是合成性质优良Y型分子筛的重要方法,相关研究不断深化成熟,以此方法合成特殊性能的Y型分子筛成功应用于催化裂化催化剂。合成具有特殊形态和结构组成的分子筛如小晶粒Y型分子筛、高硅Y型分子筛是近年来的研究热点。分别从优化合成条件、加入分散剂和使用微波加热法介绍小晶粒Y型分子筛合成研究进展。高硅Y型分子筛的合成主要分为直接合成和二次改性方法,直接合成法反应条件苛刻,存在原料浪费等问题;二次改性方法工艺流程长,易导致合成成本增加。重点讨论具有特种性能的特种Y型分子筛合成研究进展,对离子液体合成Y型分子筛、干胶转化合成Y型分子筛和高岭土合成复合分子筛等新方法进行综述,并结合其他先进的分子筛合成方法,指出Y型分子筛合成的研究方向和前景。     

3,4-二氢嘧啶-2 -酮衍生物合成研究进展

报道了最近6年来3,4二氢嘧啶酮衍生物合成研究进展,包括催化合成法、绿色合成法以及天然产物合成中的一些研究进展,为该类化合物的合成提供了详尽的文献综述。有望在药物合成、不对称合成和天然产物合成方面提供有意义的指导。     

苯并烯氟菌唑及关键中间体合成方法述评

综述了琥珀酸脱氢酶抑制剂苯并烯氟菌唑的合成方法;根据酰胺键的合成方式,合成方法可分为酰氯合成法、酰胺合成法、酯交换法、酸缩合法及肟合成法5种。对这些方法所涉及的关键中间体的合成也进行了总结,发现肟合成法具有收率高、原料易得和易于工业化操作等特点,是目前大量合成苯并烯氟菌唑的最有效方法。     

片段法合成多肽的研究

以片段合成法和直接合成法分别合成一个比较长的多肽,并用质谱和HPLC进行检测,结果显示用片段合成法合成的多肽,其合成效率、合成纯度均明显高于直接法。     

皂石矿物的合成工艺和性能简介

综述了皂石的合成方法,以及合成条件对皂石结构、性质的影响。合成方法包括水热合成法、微波辅助合成法以及非水热合成法。皂石的晶形、性质、形貌、纯度受原料和合成条件,比如温度、时间、初始p H以及聚合物的加入等因素影响。皂石的合成为粘土类矿物的形成机理,理化性质和相关的应用提供了更好的理解。     

粉煤灰合成除磷沸石的试验研究

利用粉煤灰合成沸石用于除磷,探讨了碱液浓度、合成温度、合成时间以及液固比对除磷沸石合成的影响。试验结果表明,碱液浓度1 mol/L、合成温度100℃、合成时间12h、液固比5：1时,合成沸石除磷性能最佳,对塌陷塘水中磷的去除率高达92.85%。     

现代绿色合成化学

绿色化学越来越引起了人们的广泛关注,不少来自不同领域专家学者对其做出了卓越贡献。本文在介绍了绿色合成化学的概念、理论和特点;并总结了几种新型的合成方法。包括超临界合成法、微波合成法、等离子体合成法、超声合成法和电化学合成法等绿色合成方法,并分别对其合成的原理,特点和应用等方面进行了简要的介绍。最后,对未来绿色合成化学的发展做了展望。     

塑料旋转成型的特点与研究

介绍了塑料旋转成型的原理和主要特点，对旋转成型制品中易出现的气泡和弯曲，收缩现象，以及冲击强度低的原因进行了分析研究，相应地提出了减少或消除旋转成型制品中的气泡，减少或消除制品收缩和弯曲，以及提高制品冲击强度的主要途径。     

Bubble development in a polymeric resin under vacuum

Understanding the gas diffusion and evaporation behavior in a polymeric resin under vacuum is of great importance because many types of polymer and composite products are manufactured by applying a vacuum to the production system. This article proposes a theoretical model that can describe bubble growth under vacuum by combining the mechanisms of gas diffusion and evaporation. To confirm such a model, we carried out experimental analyses including evaporation experiments with a bell jar or a tube as well as vacuum‐assisted resin transfer molding (VARTM). Particularly in the VARTM process, it was identified that many bubbles were nucleated and grew at the fiber‐matrix interface due to the applied vacuum pressure. Those results suggest that more attention should be paid to vacuum‐assisted material processing to prevent bubbles from existing in the final products. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

微发泡注塑制品表面质量的优化研究

以聚丙烯(PP)和高纯氮气为原料,采用高压短时和低压长时两种注气方式进行了微发泡注塑实验,并在以低压长时为注气方式的实验中,在不同熔体温度、注气压差和储料长度下,研究了冷却时间与制品表面出现大气泡概率之间的关系.结果表明,通过高压短时注气方式得到的制品表面出现大气泡的概率较高,严重影响制品质量;采用低压长时注气方式,制...     

Optimisation of bubble size in qc rotationally moulded parts

Abstract

Rotational moulding is one of the most important methods of manufacture of hollow plastic products. However, there are several unsolved problems that confound the overall success of this technique, including surface pin holes and internal bubbles of moulded parts, caused by inappropriate mould design and processing conditions. In this report, an L′18 experimental matrix design based on the Taguchi method was conducted to optimise the bubble size of rotationally moulded parts. Experiments were carried out on a laboratory scale biaxial rotation moulding unit. The polymeric material used to mould the parts was linear low density polyethylene. After moulding, the size of the bubbles on the surface of moulded parts was characterised by an image analysis system. For the factors selected in the main experiments, the cooling conditions and the particle size of the material were found to be the principal factors affecting the bubble size of rotationally moulded thermoplastics. In addition, mould pressurisation helped decrease the size of the bubbles. The bubble size of moulded parts was not affected by the water content of the polymeric powder, but increased with the viscosity of the materials.     

Versuchsaufbau zur beschleunigten Bildung von Fouling aus Magermilchkonzentrat

Air bubbles on heating surfaces have a siginificant influence on fouling of protein containing products. The formation of fouling has been investigated in a pilot plant under constant conditions. Fouling layers were analyzed with respect to mass, thickness and composition. Adsorption of air bubbles on the heating surface, together with a high wall temperature difference, and a low flow velocity resulted in a considerable shortening of the induction period as well as heavy deposits of fouling. The growth of air bubbles within the fouling layer increased with experimental progression.     

旋转成型工艺条件对制品内部气泡多少影响

讨论旋转成型的工艺参数对气泡形成影响和消险办法；提出要获得高质量的制品，必须使用高ＭＦＩ的物料，并具有较小的粒度，较高的加热温度。     

Mass transfer without and with chemical reaction in dispersed gas-liquid two-phase flows

Using a concentric sphere model, velocity profiles around bubbles in a bubble swarm were derived for clean and for relatively contaminated gas bubbles. The theoretical Sherwood numbers were calculated, including the effect of void fraction. These mass transfer predictions were compared with experimental results for the absorption with reaction of carbon dioxide into monoethanolamine solutions. The results indicated an appreciable contamination of the bubbles by surface active material.     

Effect on surface charges of bubbles and fine particles on air flotation process

The adhesion of fine particles onto bubbles in flotation was studied on the basis of surface charge measurements of the bubbles and particles. The surface charges of the bubbles were measured by the use of a micro-electropheresis apparatus devised in our previous study and the mechanism of the bubble charging was studied under various experimental conditions. In distilled water, the bubbles were negatively charged and the iso-electric point appeared at pH = 2.5. The surface charges of the bubbles in the surfactant solution were determined by the surfactant molecules adsorbed at the surface and depend strongly on the values of pH. The flotation efficiency of latex particles (0.923 μm) was found to be strongly influenced by the surface charges of both the particles and the bubbles. The force between the particle and the bubble was estimated from the observation of the particle attachment to the bubble surface, and a simple equation including the effects of the hydrodynamic and surface charge interactions was proposed to determine the floatability limit.     

用于不饱和聚酯树脂的消泡剂

本文分析了不饱和聚酯树脂加工过程中气泡产生的原因，描述了消泡剂的作用、机理和应用以及对产品质量所带来的积极影响。     

Bubble Nucleation and Growth in Microcellular Injection Molding Processes

Bubble nucleation and growth are the key steps in polymer foam generation processes. The mechanical properties of foamed polymer are closely related to the size of bubbles created inside the material. Thus, it is necessary to study how to improve mechanical strength by producing extremely fine bubbles inside polymer resin. We developed a theoretical framework to help produce uniformly distributed microcellular bubbles and experimentally verified the theoretical analysis results using an injection molding machine modified to make microcellular foaming products.