聚氨酯基抗菌根管充填材料的制备与性能研究

理想的根管充填材料应具有良好根管封闭性能与抗菌作用。通过在具有良好可调控性自固化聚氨酯中添加无机抗菌剂磷酸银,经先制备预聚体,再进一步聚合的方法制备新型载磷酸银聚氨酯基根管充填材料(Ag3PO4/PU)。红外光谱分析表明,制得的聚氨酯预聚物由异氰酸根(—NCO)封端,—NCO的转换率为75.2%,经进一步反应制得的聚氨酯高聚物中—NCO转换率为96.8%。依照根管充填材料的ISO标准评价了材料理化性能,结果显示其理化性能符合ISO标准的要求;抑菌环、抗细菌粘附和抑菌率实验结果表明,Ag3PO4/PU能有效抑制细菌粘附和增殖,与细菌接触培养7h后抑菌率90%,是一种有应用潜力的新型抗菌根管充填材料。     

竹纤维的表面包覆及其对浇注型聚氨酯弹性体力学性能的影响

通过一种异氰酸酯基团(—NCO)质量分数为14.5wt%的高活性聚氨酯(PU)包覆剂对竹纤维(BF)进行表面包覆获得包覆型竹纤维(PUBF),采用原位聚合法制备了包覆型竹纤维增强浇注型聚氨酯(PUBF/PU)弹性体复合材料。采用FTIR、SEM、XRD及接触角测试仪对PUBF及BF进行了表征。结果表明,BF表面成功包覆了具有活性氨基(—NH₂)封端的PU薄层,改善了BF与浇注型聚氨酯PU间的界面相容性及界面结合。复合材料中的PUBF质量分数为3wt%时,80℃下预聚体黏度仅为2.2 Pa·s,与纯预聚体黏度接近;对应PUBF/PU复合材料的拉伸和撕裂强度分别为38.0 MPa和82.9 kN/m,比纯浇注型PU分别提高51.6%和25.6%。高活性PU包覆剂预先包覆BF适合制备PUBF/PU复合材料。      

不同分子量的大豆油基多元醇的制备及其在聚氨酯泡沫塑料制备中的应用

通过热聚合法制备了3种不同分子量、羟值和分子结构的大豆油多元醇(Polyols1,Polyols2和Polyols3)。将它们与多亚甲基多苯基多异氰酸酯(PAPI27)反应制备了3种聚氨酯泡沫塑料(PU1,PU2和PU3)。通过压缩试验、拉伸试验和动态热机械分析(DMA)研究了3种聚氨酯泡沫的机械性能。测试结果表明,由高分子量和具有网状结构的多元醇(Polyols3)制备的聚氨酯泡沫(PU3)具有较高的压缩强度,拉伸强度和玻璃化转变温度。     

丝素蛋白/聚氨酯水凝胶的制备及其释药性能

以异佛尔酮二异氰酸酯(IPDI)、聚乙二醇(PEG)、聚氧化丙烯二醇(PPG)等为主要原料,合成NCO封端的阴离子型聚氨酯(PU)预聚体,经过三乙胺(TEA)中和成盐后与丝素蛋白(SF)水溶液混合,制备出具有交联结构的丝素蛋白/聚氨酯(SF/PU)水凝胶。全反射红外光谱法(ATR)表征了SF/PU水凝胶的结构;扫描电子显微镜(SEM)观察了SF/PU水凝胶的断面形态,显示出SF/PU水凝胶具有多孔结构;紫外分光光度计法研究了SF/PU水凝胶对氯霉素和环丙沙星两种药物的释药性能,药物释放时间在10h以上;抑菌圈实验表明载药后的水凝胶对大肠杆菌的生长具有抑制作用。     

多壁碳纳米管抗菌性研究

将多壁碳纳米管(MWCNTs)和聚氨酯(PU)制得MWCNTs-PU纳米材料。研究MWCNTs-PU纳米材料对大肠杆菌和金黄色葡萄球菌的杀菌效果。实验结果表明:MWCNTs能够均匀分散在PU中,增加了MWCNTs的比表面积,制得的MWCNTs-PU纳米材料对大肠杆菌和金黄色葡萄球菌的抗菌率达到100%。     

聚氨酯/聚氯乙烯半-IPN的研究——Ⅰ.聚醚氨酯/聚氯乙烯体系的合成及动态力学性能

以聚环氧丙烷二元醇(PPO,_a=1000)和二异氰酸酯(MDI)反应制备的聚氨酯预聚物和PVC溶液共混后固化聚氨酯相而合成了PU/PVC Semi-IPN。动态力学结果表明:由于PU和PVC的互穿改善了PU与PVC之间的相容性,其动态力学谱(DMS)在很大程度上依赖于PU/PVC原料配比、PVC分子量、PU交联密度及PU中硬段含量等因素。DMS上Semi-IPN对应PVC的T_g比纯PVC的T_g高出15—20℃,笔者认为:导致这一现象的原因是PVC和PU硬段之间相互作用的结果。     

耐热型聚氨酯的合成制备与性能

提高聚氨酯耐热性能是聚氨酯应用研究热点。文章以聚醚多元醇(PPG)、4,4′—二苯基甲烷二异氰酸酯(MDI)、3,3—二氯—4,4—二氨基二苯基甲烷(MOCA)为主要原料,采用预聚体法制备聚氨酯(PU),探讨了扩链系数对聚氨酯耐热性能的影响。结果表明,随着扩链系数的增加,聚氨酯的综合力学性能、耐热性能先升高后降低,动态机械分析(DMA)显示,增加扩链系数使得PU玻璃化转变温度(T_g)的内耗峰向高温方向移动。当扩链系数为0.04时,聚氨酯力学性能最佳,拉伸强度为64.16 MPa,弯曲强度为84.69 MPa,冲击韧性为8.88 kJ/m~2,阻尼因子最大值(Tanδmax)为1.108,热分解初始温度达到315℃。     

载银丝素/聚氨酯复合材料的合成及抑菌性研究

以盐溶酶解法制得纳米级丝素蛋白(SFP)粉末,将其与医用聚氨酯(PU)共混,并通过还原法将纳米Ag引入SFP/PU体系,得到载银丝素/聚氨酯(SFP/PU/Ag)复合材料。UV确认了材料中纳米Ag是由SFP还原获得,硝酸银用量为SFP/PU体系质量的1%时最为合适。IR和DSC表明SFP/PU/Ag三种组分结合紧密,已通过氢键、配位络合等融为一体。抑菌试验结果显示SFP/PU/Ag中的抑菌性能通过纳米Ag达成,且低浓度的纳米Ag即具有了优越的抑菌性能,该复合材料具备医用抗菌材料的应用前景。     

基于可逆硼氧六元环交联的自修复聚氨酯

自修复聚氨酯一直是近年来的研究热点。文中以聚四氢呋喃二醇(PTMEG)、异佛尔酮二异氰酸酯(IPDI)和4-羟基苯硼酸(HPBA)为原材料，制备了基于硼氧六元环的高强度自修复聚氨酯(PU)。利用傅里叶变换红外光谱仪对其进行结构表征；利用热重分析和差示扫描量热法考察其热性能；研究了PU的力学性能、自修复性能和形状记忆性能。结果表明，硼氧六元环结构的引入使PU具有高强度和优异的自修复性能。当HPBA含量从0 mmol增加到0.75mmol时，PU的拉伸强度从(23.8±1.8) MPa提高到(51.3±4.2) MPa；在80℃修复36 h后，PU/P-0.7的修复效率达到80.9%±4.2%。此外，PU还具有热响应的形状记忆性能，75℃时，其形状回复率达到96.1%±1.7%。利用凝胶渗透色谱法测试了PU的相对分子质量，其数均分子量为3.28×10⁴。     

镁合金/环氧聚氨酯涂层体系的耐腐蚀性能

环氧聚氨酯(ER/PU)涂层具有良好的电绝缘性、耐腐蚀性以及与金属基体的附着力,能够有效地阻挡或缓解Cl-,NO3-,SO2-4,H2O和O2等对镁合金基材的侵蚀,提高镁合金的耐腐蚀性能.为此,采用附着力、铅笔硬度测试,浸泡、失重法、盐雾及电化学试验等方法研究了聚氨酯(PU)涂层及环氧聚氨酯(ER/PU)涂层对镁合金的腐蚀保护效果及机理.结果表明,2种涂层体系都显著提高了镬合金的耐腐蚀性能,与基材附着良好、且硬度高,但后者效果更好.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.