丙交酯的合成与聚合

丙交酯是由乳酸合成聚乳酸的中间体,采用新型La Ti复合氧化物催化乳酸合成丙交酯,粗丙交酯经乙酸乙酯纯化后,差热分析仪测得其熔点为126 4℃,纯化后的丙交酯在一定条件下,经辛酸亚锡引发,开环聚合成聚乳酸,并用红外光谱和差热分析仪对聚乳酸进行了表征。     

氧化锌-辛酸亚锡催化合成丙交酯

采用氧化锌和辛酸亚锡为催化剂,在高真空条件下共同催化合成丙交酯.比较了两种催化剂加入方式的不同对丙交酯产率的影响,发现当脱完自由水后同时加入氧化锌(ω=1%)和2 mL辛酸亚锡,丙交酯的粗产率可以达到90%以上.     

D,L-丙交酯的合成条件优化研究

制备了SO42-/Al2O3/La3 固体超强酸和辛酸亚锡复配作为丙交酯合成的催化剂.经多种催化剂的催化效率比较,进行多组实验发现该催化剂在较高反应压力下高产丙交酯的合成条件.结果表明,催化剂、反应温度、脱水时间等对丙交酯的产率有显著影响.     

生物可吸收材料PDLLA的聚合条件研究

通过乳酸脱水合成出高纯度的D ,L 丙交酯。以辛酸亚锡为引发剂 ,进行丙交酯开环聚合为聚乳酸 (PDLLA)的实验研究。讨论了D ,L 丙交酯开环聚合的影响因素和PDLLA聚合条件     

聚乳酸／纳米二氧化硅复合材料分子量的影响因素

以丙交酯和改性后的纳米二氧化硅为原料,在催化剂作用下,用原位聚合法制备了聚乳酸纳米二氧化硅复合材料。讨论了催化剂的种类和用量、反应时间、反应温度、纳米二氧化硅的用量等因素对复合材料分子量的影响。结果表明,最优的反应条件为:采用辛酸亚锡为催化剂,催化剂用量和二氧化硅用量分别为丙交酯用量的0.25%(质量分数,下同)和5%,在140℃油浴中,氮气保护下反应72 h,可得到重均分子量为1.5091×105的聚乳酸纳米二氧化硅复合材料。     

单模聚焦微波作用下端炔基修饰的聚(L-丙交酯)的合成与表征

在单模聚焦微波辐射作用下,以辛酸亚锡为催化剂,炔丙醇为小分子引发剂引发L-丙交酯开环聚合合成了端炔基修饰的聚(L-丙交酯)。通过正交实验考察了各种反应条件对产物产率的影响,得出最佳的聚合反应条件如下:反应温度110℃,微波功率45W,辐照时间45min,催化剂用量0.1%。在此基础上,通过改变n(L-丙交酯)∶n(炔丙醇)投料比合成了一系列端炔基修饰的聚(L-丙交酯),通过FT-IR、1H NMR、DSC、XRD和GPC对其结构与性能进行了研究。结果表明,在微波作用下,快速、高效地合成了端炔基修饰的聚(L-丙交酯)目标产物,且产物的结构与性能可以通过改变n(L-丙交酯)∶n(炔丙醇)投料比在一定程度上进行调控,随着L-丙交酯投料量增大,产物的分子量逐渐增大,熔点逐渐升高。     

合成中间体丙交酯的制备与纯化

用辛酸亚锡Sn(oct)2作为催化剂制备丙交酯,经重结晶得到高纯度的丙交酯。通过熔点测定、红外光谱对丙交酯进行了确认。讨论了制备过程中的影响因素,与氧化锌作催化剂相比,改进了合成方法,缩短了反应时间,提高了产率。     

低温常压下高分子量左旋聚乳酸的微波合成及表征

以辛酸亚锡为催化剂低温常压下引发左旋丙交酯(LLA)开环聚合,快速高效地合成了性能良好的高分子量左旋聚乳酸(PLLA).通过正交实验研究了催化剂用量、反应温度和时间对产物分子量的影响,在催化剂用量0.21%(质量分数),反应温度100℃,反应时间60min时得到产物粘均分子量高达16.21×104.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)对产物的结构进行分析,结果证明利用微波能有效地合成左旋聚乳酸,通过差式扫描量热(DSC)、X衍射(XRD)、旋光度和力学性能对左旋聚乳酸膜的性能进行表征,结果显示产物纯净,其结晶度为85.6%,光学纯度为98%,有良好的力学性能.     

3-甲基吗啉-2,5-二酮与L-丙交酯共聚物的制备和表征

以辛酸亚锡为催化剂,合成了3-甲基吗啉-2,5-二酮(MMD)与L-丙交酯(L-LA)的共聚物,并用FT-IR、HNMR、粘度测定法对共聚物进行了表征.结果表明,氨基酸被引入到聚乳酸的主链中,且聚合物的组成可根据投料比例的不同在较大范围内调节.     

超临界CO2中聚乳酸的合成及表征

以辛酸亚锡为催化剂用超临界二氧化碳作溶剂成功地实现了L-丙交酯的开环聚合,聚合产物用FT-IR、^1H-NMR、^13C-NMR、DSC和GPC进行了分析表征,结果表明：超临界二氧化碳流体中左旋丙交酯开环聚合不是离子型聚合．可能是配位一插入聚合。所合成的聚乳酸具有很高的光学活性;所得聚合物无论分子量大小,都具有熔点和中等结晶度,且随分子量的增大而升高。     

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 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.     

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.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.