新型改性聚乳酸及其亲/疏水性研究

合成了基于马来酸酐改性聚乳酸（MPLA）和丁二胺的新型改性聚乳酸（BM-PLA），旨在提高聚乳酸的亲水性，克服乳酸和MPLA在降解过程中的酸性，并为进一步引入多肽和胶原等生物信号分子提供活性基团。通过红外光谱测定到了丁二胺已成功引入到MPLA中，利用接触角和吸水率评价了BMPLA的亲/疏水性变化，表明丁二胺改性所得BMPLA的亲水性相对于PDLLA和MPLA已大大改善，测定了材料在12周降解过程中的pH变化。表明丁二胺改性聚乳酸不表现酸致自加速降解特征，未出现pH陡降现象，已完全克服了聚乳酸和马来酸酐改性聚乳酸降解过程中的酸性，上述研究结果提示，丁二胺改性聚乳酸是一族新型的具有优良亲水性和良好降解行为的组织工程材料，预示着它可望具有优良的细胞亲和性，在组织工程中具有重要的应用潜力。     

反应挤出法制备马来酸酐接枝聚乳酸

采用反应挤出方法制备了聚乳酸(PLA)与马来酸酐(MAH)的接枝共聚物,研究了工艺条件和配方对产物接枝率和熔体流动速率的影响。结果表明,聚乳酸的接枝反应主要依赖于大分子侧链自由基进行,过高的螺杆转速或过高的挤出反应温度会引发聚乳酸的降解反应,不利于产物接枝率的提高;在适宜的反应条件下(马来酸酐含量2%,DCP含量0.35%,温度180℃,螺杆转速100 r/min),可以方便制得马来酸酐接枝聚乳酸产物(接枝率≥0.45%);SEM观察显示,马来酸酐接枝聚乳酸有效改善了PLA/淀粉共混材料的相容性。     

超临界CO2反复循环萃取法制备PLA/TCP多孔组织工程支架材料

相对于传统的超临界CO2（SC—CO2）一次性升压法，采用SC—CO2反复循环萃取法制备了聚乳酸（PLA）／磷酸三钙（TCP）复合多孔支架材料，以提高材料的孔洞连通率。本文研究了材料的开孔率，不同PLA和TCP配比材料的孔洞形态以及材料的力学性能。结果表明，反复循环萃取法制备的材料比传统的一次性升压法制备的材料的开孔率可以提高10%左右，孔径在200-300μm之间，孔壁上有丝网型等几种适合细胞种植的特殊微隙形态；TCP在PLA支架中的分散性很好；材料压缩模量和压缩强度分别可达71.8和7．1MPa，比单纯的PLA材料明显增加。     

芦苇秸秆纤维改性及与聚乳酸的共混

秸秆天然纤维作为填料或增强材料可应用于复合材料领域,但由于其存在大量的亲水基团,与非极性聚合物材料界面相容性差影响着复合材料的性能,因此对植物纤维的化学改性成为改善界面结合的有效手段。文中采用固相力化学法制备马来酸酐酯化改性芦苇秸秆(MA-RS),扫描电镜(SEM)观察到马来酸酐结合外力的作用下秸秆发生解纤,纤维具有较高长径比;同时红外光谱及X射线光电子能谱测试表明,纤维表面马来酸酐基团的取代度随处理时间的延长而逐渐增大。改性秸秆与聚乳酸共混制备得到复合材料,由于马来酸酐的接枝改变秸秆纤维表面性质,提高了秸秆纤维与聚乳酸之间的相容性和界面结合力。力学测试结果表明,拉伸强度提高约16%,冲击强度提高约30%;SEM观察断面形貌表面,改性秸秆比未改性秸秆与PLA基体具有更好的界面相容性。     

MAH/GMA共接枝聚乳酸对木粉/PLA复合材料性能的影响

采用熔融接枝法分别制备马来酸酐接枝聚乳酸、甲基丙烯酸缩水甘油酯接枝聚乳酸和马来酸酐/甲基丙烯酸缩水甘油酯共接枝聚乳酸,并利用红外光谱对接枝共聚物进行结构表征。分别以三种接枝共聚物为相容剂,采用注塑成型制备了木粉/PLA复合材料。利用扫描电子显微镜(SEM)对复合材料的断面形貌进行微观分析,结果表明,加入不同接枝共聚物后木粉/PLA复合材料两相看不出明显相界面,界面相容性得到改善。对不同接枝共聚物制备的复合材料的力学性能、加工流动性能和动态流变性能测定的结果显示,加入MAH/GMA共接枝聚乳酸后的木粉/PLA复合材料和未添加相容剂的复合材料相比,拉伸强度和冲击强度分别提高了9.54%和7.23%,复合体系的平衡扭矩和剪切热提高,储能模量及复数黏度均增大。     

聚(D,L-乳酸)基仿生聚合物材料的合成与表征

探索一种新型聚乳酸基仿生聚合物材料的制备新方法.具体实验步骤是:利用聚乳酸上叔碳原子的自由基反应活性,在过氧化二苯甲酰的催化作用下,将马来酸酐引入聚乳酸侧链上,以此提供高反应活性的酸酐键;然后利用酸酐基团与-NH2发生N-酰化反应这一特点,将脂肪族二胺引入聚乳酸侧链上,从而克服聚乳酸降解产物的体液环境呈酸性的缺陷;再用碳二亚胺作缩合剂,在二胺改性聚乳酸材料中共价引入一种细胞粘附肽段Arg-Gly-Asp-Ser(RGDS),赋予材料生物活性和生物特异性,这样就制备了一种新型聚乳酸基仿生材料.采用MALLS、FTIR和XPS对仿生材料进行结构表征;采用罗丹明比色法、茚三酮显色法和氨基酸分析仪检测法对仿生材料中的马来酸酐、二胺和粘附肽RGDS进行定量测定.结果表明,按文中所述之制备技术,在不改变聚乳酸材料主链结构的前提下,该仿生材料中粘附肽RGDS的含量是5.12μmol/g.这就形成了一种具有类似细胞外基质的新型仿生材料.     

高分子专利

专利名称:一种生物活性聚乳酸的制备方法、产品及应用专利申请号:200310121036.7公开号:CN1556130申请日:2003.12.31公开日:2004.12.22申请人:潘君本发明提供了一种采用马来酸酐改性的聚乳酸和生物活性物质为原料,制备生物活性聚乳酸材料的方法及其产物和应用,方法步骤:1直接加     

E-MAH-GMA共混增韧改性PLA的研究

聚乳酸(PLA)中加入不同比例的乙烯-马来酸酐-甲基丙烯酸缩水甘油酯三元嵌段共聚物(E-MAH-GMA)对其进行增韧改性。用傅立叶变换红外光谱仪对材料进行表征;用熔融指数测量仪对流动性进行分析;同时测试了材料拉伸、冲击、弯曲等力学性能,结果表明:E-MAH-GMA对PLA有增韧作用,添加20份的E-MAH-GMA时,PLA共混材料的冲击强度为95.71kJ/m2,比纯的PLA提高了408%;拉伸强度、弯曲强度有所下降,断裂伸长率略有提高。     

界面改性对GMT—PP复合材料力学性能的影响

研究了不同界面状态对ＧＭＴ－ＰＰ复合材料层间剪切强度,弯曲强度及模量,压缩强度及模量,冲击强度等力性能的影响。实验结果表明,基体中填加光引发和ＢＰＯ引发的马来酸酐接枝聚丙烯且玻纤表面用硅烷偶联剂处理可显著提高复合材料界面强度,进而提高其宏观力学性能。     

马来酸酐化在聚合物材料设计中的应用

马来酸酐化在聚合物材料设计中有广泛的应用，可酸酐化的聚合物有聚烯烃、双烯烃聚合物和极性聚合物。由酸酐化聚合物可以进行以下几方面的设计：（１）极性基团的引入；（２）梳型支化结构的产生；（３）交联网络的形成；（４）荧光标记聚合物的制备；（５）界面增容作用的形成；（６）偶联作用。     

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.