功能型多孔聚合物微球的制备及其缓释性能研究

利用超声分散改进的二步溶胀法制备4～9μm的聚苯乙烯-二乙烯苯(PSt-DVB)多孔微球,并以防晒剂parsol 1789为模型组分考察了其缓释性能.通过SEM和BET等手段表征微球表面形貌和孔结构,并研究了超声分散时间、种球类型、交联单体浓度等因素对微球性能的影响.确认超声分散的应用可以明显缩短溶胀时间;种球的粒径和分子量受分散介质极性影响较大,种球的单分散性直接决定最终粒子的形貌;随交联单体浓度增大,微球比表面积上升、孔径下降.制得的多孔聚合物微球用作化妆品活性物载体时,具有良好的缓释作用.     

种子溶胀聚合法制备微米级聚苯乙烯微球

以分散聚合法制备的平均粒径为7.7μm的聚苯乙烯微球为种子,与溶胀剂和单体、引发剂的混合物经二步溶胀聚合法溶胀聚合后,制备大粒径单分散聚苯乙烯微球,并讨论溶胀剂的种类、溶胀剂用量、单体用量、单体和引发剂的加入方式、溶胀温度等因素对聚苯乙烯微球粒径及单分散性的影响。结果表明:当邻苯二甲酸二丁酯与聚苯乙烯种子的质量比为7,单体与聚苯乙烯种子质量比为9,且引发剂与单体同时加入,溶胀温度30℃时,可制得平均粒径为12.2μm左右且单分散性较好的聚苯乙烯微球。     

大粒径由羧基修饰的交联聚苯乙烯微球的制备与表征

以分散聚合法制得的聚苯乙烯微球为种子,以1,2-二氯乙烷为溶胀剂、己二酸二辛脂(DOA)为助溶胀剂、二乙烯基苯(DVB)为交联剂及甲基丙烯酸(MAA)或丙烯酸(AA)为水溶性功能性单体,采用活性溶胀聚合法成功制得大粒径由羧基修饰的交联聚苯乙烯微球.研究了溶胀剂种类及活性种球粒径对交联聚苯乙烯羧基微球最大平均粒径及粒径分...     

微米级聚苯乙烯微球合成过程反应条件的优化

用分散聚合法合成4~8μm的单分散聚苯乙烯微球,实验考察反应温度对体系的黏度、微球分子量及微球密度等结构参数的影响,同时考察反应温度以及单体、引发剂和稳定剂等分散聚合的主要组分对所合成的聚合物微球粒径及粒径分布的影响。结果表明,反应温度为70℃时,制备的单分散聚苯乙烯微球结构最致密,微球产率较高,微球耐有机溶剂的能力较强;随着初始单体浓度、引发剂用量的增加和反应温度的升高,最终得到的聚苯乙烯微球粒径虽有所增大,但微球粒径分布变宽;随着稳定剂用量的增加,最终微球粒径减小,粒径分布变窄。     

微米级单分散聚苯乙烯微球的制备

用分散聚合法合成2～6μm单分散好的聚苯乙烯微球,分别考察单体、稳定剂的两步加料方式,以及初始单体浓度、引发剂用量、反应温度等对所合成的聚合物微球粒径及粒径分布的影响。结果表明:两步加料方式可以显著改善微球的单分散性;随着初始单体浓度、引发剂用量增加和反应温度的升高,最终得到的聚苯乙烯微球粒径虽有所增加,但微球粒径分布变宽。将反应液体积放大、单次合成聚苯乙烯微球量不低于250g时制备出的2～6μm系列的聚苯乙烯微球,用扫描电镜等进行表征可知,所制备的聚苯乙烯微球球形度均大于0.95,相对标准偏差均小于5%。     

双马来酰亚胺交联单分散聚苯乙烯微球的制备及表征

采用分散聚合法,以苯乙烯为单体,二苯甲烷双马来酰亚胺(BDM)为交联剂,制备了单分散交联聚苯乙烯微球(St/BDM)。研究了分散聚合反应中单体(St)、引发剂(AIBN)、分散剂(PVP)、交联剂(BDM)用量对微球粒径和粒径分布的影响。通过优化反应条件,合成了平均粒径为3.03μm(ε=0.05)的单分散交联聚苯乙烯微球。热稳定性分析和耐溶剂性实验结果表明,二苯甲烷双马来酰亚胺(BDM)交联的聚苯乙烯微球热稳定性和耐溶剂性能比线性的聚苯乙烯微球有了很大的提高。当失重5%时,聚合物的热分解温度由交联前的306℃上升到交联后的328℃。     

柚皮素分子印迹聚合物微球的制备

用无皂乳液聚合法合成了微米级聚苯乙烯微粒,并以其为种球,采用单步溶胀聚合法制得了单分散柚皮素分子印迹聚合物微球(MIPMs),考察了溶胀比、水油比、溶剂种类及交联剂用量等对MIPMs形态、粒径及粒径分布的影响,并用静态吸附实验考察了MIPMs的分子识别性能.结果表明,当用1.50μm的聚苯乙烯为种球,环己醇或氯仿为溶剂,20mmol 乙二醇二甲基丙烯酸酯为交联剂,水油比为7∶1,溶胀比控制在27～60之间时,可获得一系列粒径在4.5～6.0μm单分散的MIPMs.制得的MIPMs对模板分子具有较强的特异吸附能力,以槲皮素为竞争底物,其分离因子达1.96.     

单分散聚苯乙烯微球的制备及二维胶体晶体的自组装

以苯乙烯为原料、过硫酸钾为引发剂,采用无皂乳液聚合法成功地制备出具有良好球形度的单分散聚苯乙烯微球.研究了在聚苯乙烯微球合成过程中单体浓度、引发剂浓度、聚合时间对粒径及分布的影响.实验结果表明,适当改变单体浓度、引发剂浓度、聚合时间可以得到不同粒径的聚苯乙烯微球,且微球单分散性良好.采用自组装技术组装单分散聚苯乙烯微球,获得了二维有序聚苯乙烯胶体晶体.     

溶胀法制备含铕配合物的聚苯乙烯荧光微球

用溶胀剂溶胀单分散的聚苯乙烯微球,使稀土配合物铕-二苯甲酰甲烷-邻菲罗啉[Eu(DBM)3phen]渗透进入微球中,制备出含铕配合物的聚苯乙烯荧光微球。系统的研究了制备过程中溶胀剂的选择和用量、Eu(DBM)3phen的用量及溶胀时间对微球形貌和荧光强度的影响。用环境扫描电子显微镜、荧光显微镜和荧光分光光度计对微球的形貌、粒径和荧光强度进行了表征。结果表明,通过条件优化,可以制备出单分散的高亮度荧光微球,微球中铕配合物的最大含量为5.5%,并且荧光微球在pH=1～14范围内均有良好的稳定性,在生物医学领域有很好的应用前景。     

微波辐射分散聚合制备单分散聚苯乙烯微球

微波辐射代替传统加热方法,进行苯乙烯分散聚合,制备拉径大小在200nm-500nm之间,且为单分散的聚苯乙烯微球;探讨了单体、稳定荆、引发荆的浓度对微球粒径大小和分布的影响。研究结果表明,微波辐射分散聚合制备的聚苯乙烯微球拉径,小于常规加热分散聚合制备的微球粒径,且微波辐射制得的微球单分散性更好。     

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.     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

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.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.