可聚合乳化剂的类型及乳液聚合

介绍了一些新型的乳化剂－可聚合乳化剂,分别亲水基类型,可聚合基团类型和可聚合基团在分子中位置等对其进行了分类,综述了各类可聚合乳化剂研究及应用情况,展望了其发展前景。     

Influence of Emulsifiers on the Formation and Crystallization of Solid Lipid Nanoparticles

The production of solid lipid nanoparticles by means of hot homogenization uses two different techniques: emulsification (liquid state) and crystallization (solid state). Both these processes depend on many parameters, such as composition, energy input, or geometry of the emulsification device. In former investigations known from the literature, the influence of the emulsifier concentration and the potential of controlling the polymorphic forms of the solidified particles were not investigated in detail. Here, these two factors were analyzed on the example of palm oil particles stabilized with emulsifiers suitable for foods. The influence of the emulsifier concentration on the resulting droplet and particle sizes is very high, up to a certain level. However, beside this influence, the polymorphic form of the solidified particles can be controlled by the right choice of emulsifier type and concentration.     

Development and Application of a Rheological Method to Investigate Crystallization of Palm Oil

Structuring of fatty products is important in producing palatable food products. Saturated fat (SAFA) crystals are needed to bring structure to many products (such as bakery or confectionery). In a product control of the structure by fat nucleation and crystallization, it is important to deliver the correct performance. Many techniques only work on quiescent systems and give limited information about the sheared systems that are generally found in industrial production of products. This article presents a novel rheological technique that can be used to probe crystallization and network structure under sheared conditions. The results show that crystallization of palm oil can be divided into different key stages. These result from initial nucleation, structuring by the crystals, polymorphic transformation, further structure building, and then subsequent relaxation. Significant postcrystallization (sintering) events occur over at least a day. It is seen that the shear rate leads to possibilities for crystallization control. Higher shear gives a reduction in network strength (as measured by G′) of the initial crystal network. However, after longer posthardening, results are very similar. This work enables the development of a fast tool that can be used to monitor structure formation in fats and reveals the relative importance of the nucleation–crystallization and postcrystallization events in sheared systems.     

环氧树脂乳液及其乳化剂的进展

综述了国内外环氧树脂乳液的制备技术及新型乳化剂的最新研究进展。介绍了环氧树脂乳液用助剂、乳液的稳定性及乳液的应用。详细介绍了外加乳化剂型环氧树脂乳液。     

乳液增稠技术的研究进展

增稠剂可以提高物系黏度,使物系保持均匀稳定的悬浮状态或乳浊状态,或形成凝胶。目前常用的增稠剂有纤维素及其衍生物类、聚丙烯酸及其共聚物类、非离子缔合型聚氨酯类等,对不同增稠剂特性的了解对于根据需要选择合适的增稠剂非常重要。主要以纤维素及其衍生物类、聚丙烯酸及其共聚物类、非离子缔合型聚氨酯类这三类主要的增稠剂为主,综述了乳液增稠的相关增稠机理以及研究应用技术。     

Emulsion Semi-Batch Terpolymerization Process Using Hybrid Emulsifiers for Synthesizing New Emulsion Pressure Sensitive Adhesives (EPSAs)

In order to obtain a suitable formulation of designing direct synthesis of acrylic latexes to be used as emulsion pressure sensitive adhesives (EPSA), having high shear resistance together with high peel strength and tack, free radical emulsion polymerization of hard monomers, such as styrene (St), vinyl acetate monomer (VAM), methyl methacrylate (MMA) and butyl methacrylate (BMA), and soft monomers, butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA) along with multifunctional monomers, namely acrylic acid (AA), were carried out. The effect of the type of hard and soft acrylic monomers, the type and level of emulsifiers, and the initiator concentration on the emulsion polymer stability and final properties of the EPSA were investigated. The results obtained showed an optimized composition. This composition led to a significant increase in shear strength and peel strength to 909 kPa and 0.45 N/mm, respectively, while the synthesized PSA was still too tacky, 5.5 cm, according to adhesion performance testing. For making this successful balance of the conflicting adhesion properties of PSA, a series of anionic and nonionic emulsifiers were investigated. It was interestingly found out that the hybrid emulsifiers (anionic coupling with nonionic) with the optimized compositions could enhance the stability of the emulsion system and improve the properties of PSA compared with the mono-emulsifier. We also tried to adjust the initiator concentration with the level of the optimized hybrid emulsifier, polyoxyethylene alkyl phenyl ether (K30), dioctyl sulfosuccinate (DOSS), and sodium vinyl sulfonate (SVS) with the ratio 2:1:1, resulting in a highly preferred proportion of the 0.5 part of the initiator versus 1.25 parts of the hybrid emulsifier in terms of the total weight of the monomers.     

Melt Crystallization of Ammonium Dinitramide (ADN) Investigated by Means of X-ray Diffraction

Ammonium dinitramide (ADN) is a promising oxidizing agent for solid rocket propellants. In situ XRD investigations of ADN and ADN suspensions have been performed in order to understand and refine the emulsion crystallization process for manufacturing spherical ADN particles (prills). The investigation revealed that the melt crystallization behavior depends on ADN quality, humidity, maximum temperature of temperature cycles, and suspension agents. Further investigations will focus on additives for controlling the mechanisms investigated, e.g., by seeding.     

可聚合乳化剂的类型及乳液聚合（续）

介绍了一些新型的乳化剂－可聚合乳化剂,分别按亲水基类型,可聚合基因类型和可聚合基因在分子中位置等对其进行了分类。综述了各类可聚合乳化剂研究及应用情况,展望了其发展前景。     

新型药物结晶技术

以药物结晶实例介绍了近年来发展的新型药物结晶方法：超临界流体结晶：准乳化结晶；微重结晶法。同时介绍了结晶技术在药物晶型控制，压缩性能和释放性能改进方面的应用。     

反应型乳化剂及其在乳液聚合中的应用

对各类反应型乳化剂的结构特征、合成方法及其在乳液聚合中应用的最新研究进展作了详细介绍,并对反应型乳化剂的应用前景进行了展望。     

Retardation of Crystallization of Diacylglycerol Oils Using Polyglycerol Fatty Acid Esters

Liquid oil containing high concentrations of diacylglycerols (DAG > 80 %, hereafter referred to as DAG-rich oil) is generally more likely to cause precipitation at chilled temperatures (clouding phenomena) than triacylglycerol-based oil. The clouding phenomena that occur during long-term storage of DAG-rich oil are unwanted in consumer products and therefore, must be prevented. In the present study, we attempted to retard precipitation by adding food emulsifiers, polyglycerol fatty acid esters (PGFE) containing different fatty acid moieties. DSC, polarized optical microscopy, and X-ray diffraction studies revealed that the addition of 0.2 % PGFE containing palmitic and oleic acid moieties very effectively retarded precipitation in the DAG-rich oil. To confirm these observations, we prepared a model DAG oil to mimic DAG-rich oil and examined the retardation behavior of high-melting DAG fractions using PGFE. The results are discussed in terms of the effects of PGFE additives on the pre-nucleation processes of high-melting fractions in DAG-rich oil.     

聚醋酸乙烯酯乳液合成工艺的研究

介绍了聚醋酸乙烯酯乳液的合成工艺 ,主要考察了单体、乳化剂、引发剂、反应温度及聚乙烯醇对乳液粘度、固含量的影响。当反应温度为 75℃ ,乳化剂、引发剂用量分别为单体总量的 0 .15%和 0 .6 %条件下 ,得到粘度为 5 .8Pa·s、固含量为 4 2 %、pH值为 6～ 8,带蓝光的乳白色聚醋酸乙烯酯乳液。     

乳状液膜分离技术在废水处理中的研究进展

乳状液膜分离技术是一种新型、高效、低成本的分离手段,近年来在环境保护是到广泛应用,本文较详细的介绍了这一新型手段在废水处理方面的研究和应用情况。     

沉淀结晶过程中的添加晶种技术

总结了沉淀结晶过程中的添加晶种技术 ,对添加的晶种量、晶种大小 ,以及添加时的结晶条件等作了探讨 ,并对包含有晶种操作和不含晶种操作的沉淀结晶产品作了比较 ,认为添加晶种操作对于多数沉淀结晶过程是有益的     

新兴的高压结晶分离技术及其研究现状

本文对高压结晶分离技术的原理、特点、应用及其研究现状进行了综述。     

Effectiveness of Polyoxyethylene Nonionic Emulsifiers in Emulsification Processes Using Disc Systems

Additives such as emulsifiers and stabilizers (viscosity enhancers or polymers) are needed to stabilize emulsion systems against coalescence and creaming. A way to reduce emulsifier input by determining the effectiveness of different emulsifiers is described. Only disc systems with optimized configuration are applied for emulsification. Polysorbates are taken as an example for emulsifiers. The viscosity was increased with pectin as a viscosity enhancer to allow higher energy inputs by the disc systems and, therefore, to improve droplet disruption. The attainable mean diameters of oil droplets stabilized only by pectin were compared with the resulting mean diameters of oil droplets of emulsions containing polysorbates. Polysorbate 20, the emulsifier with the highest water solubility of all here described emulsifiers, proved to be the most effective in decreasing the mean diameter of the disperse phase when using disc systems. An optimal emulsifier concentration of 2 wt‐% for emulsions at low viscosities is observed for all polysorbates and for the whole range of oil concentration.     

聚丙烯酸酯乳液生产工艺研究

聚丙烯酸酯外用乳胶漆其优良的性能主要决定于丙稀酸脂聚合乳液的性能。从聚丙稀酸脂单体、聚丙烯酸酯的乳化聚合、配方及助剂等方面对生产操作及工艺研究进行了探讨,以获得质量更佳的乳液,确保漆膜的优良特性。     

草甘膦连续结晶技术的开发与应用

测定了实际料液中草甘膦的溶解度和过饱和度特性,并根据此特性设计建立了由2个Krystal结晶器串联组成的年产10000t草甘膦连续结晶系统.运行结果表明:系统设计合理,达到了设计目标;连续结晶工艺相对间歇结晶工艺具有占地面积小、自动化程度高、操作简单、操作人员少、产品粒度均匀、节能降耗达50%以上等优点;系统可连续稳定运行60 d以上.     

Encapsulation of Aqueous Components in Solid Fat Beads: Studies of a Model Dye and a Probiotic Culture

Solid fat beads containing aqueous droplets of either a water soluble dye (Brilliant Blue) or a suspension of viable probiotic bacteria (Bifidobacterium animalis ssp lactis) were produced by dropping a water‐in‐molten fat emulsion into cold water or onto a cold plate, respectively. Hydrogenated palm stearin beads containing 20 % dye solution were 4.6 ± 0.2 × 2.7 ± 0.4 mm and the average bead weighed 0.0103 ± 0.0003 g. The dye was completely released into an external aqueous phase after 24 h stirring at temperatures above the melting point of the fat but at temperatures where the fat was solid very little dye was released into an external aqueous phase. When a bacterial suspension was used as the internal phase of 20 % hydrogenated palm stearin/80 % palm kernel oil beads, the beads contained 8.44 log CFU/g. The encapsulated organisms were more resistant to acid stress than an unencapsulated control (loss of 0.7 versus 5.75 log CFU/g). This approach offers a way to protect probiotic bacteria during transit through the stomach. Practical application: by encapsulating bacteria in solid fat they become more resistant to acids. Small beads could be added to foods or swallowed as a pill as a way to deliver viable probiotic organisms to the lower digestive tract.