微波辐射四元共缩聚聚酰亚胺的合成与表征

以3,3′,4,4′-二苯甲酮二酐(BTDA)、均苯四甲酸二酐(PMDA)、4,4′-二氨基二苯砜(DDS)和4,4′-二氨基二苯醚(ODA)为单体,采用微波辐射溶液缩聚得到一种四元共缩聚聚酰胺酸(PAA),然后经亚胺化得到聚酰亚胺(PI)。通过对数比浓黏度(ηinh)、红外光谱(FT-IR)、核磁(1H-NMR)、溶解性测试和热重分析(TGA)对聚合物进行了结构表征和性能测试。结果表明,微波辐射能显著提高反应速度、PAA的相对分子质量和产率;FT-IR表明生成了预期的聚合物;1H-NMR表明PAA亚胺化度达95%以上;溶解性测试表明PAA具有较好的溶解性;TGA表明所合成的PI具有较高的热氧化稳定性和热稳定性。     

微波辐射合成含三苯胺结构的超支化聚酰亚胺及其表征

在微波辐射条件下,采用两步法以3,3′,4,4′-二苯酮四羧酸二酐(BTDA)和4,4′,4″-三氨基三苯胺(TAPA)为单体,先合成出含三苯胺结构的氨基封端和酐基封端的超支化聚酰胺酸,再经化学亚胺化和热亚胺化分别制得了相应的超支化聚酰亚胺(AM-HBPI和AD-HBPI)。FT-IR和1H-NMR验证了所得AM-HBPI和AD-HBPI的分子结构。TG测试表明此两种芳香族HBPI具有优异的热稳定性,N2中10%热失重温度(Td10%)在540℃以上。溶解性测试发现化学亚胺化得到的HBPI具有优良的溶解性能,可以溶于常见的强极性非质子溶剂。此外,它们还具有极佳的紫外-可见光吸收性能和荧光发射性能。     

2,5-双(4-氨基-2-三氟甲基苯氧基)叔丁基苯及其聚酰亚胺的制备和性能研究

通过两步反应制备得到2,5-双(4-氨基-2-三氟甲基苯氧基)叔丁基苯,将其分别与均苯四甲酸二酐(PM-DA)、3,3’,4,4’-四羧酸二苯醚二酐(ODPA)、3,3’,4,4’-二苯酮四酸二酐(BTDA)、3,3’,4,4’-联苯四酸二酐(BPDA)、双酚A二酐(BPADA)通过缩聚和热亚胺化制备得到5种性能优异的聚酰亚胺薄膜。结果表明薄膜的玻璃化转变温度(Tg)高于210℃,起始分解温度高于510℃;吸水率低于0.9%;介电常数介于2.90～3.15之间;杨氏模量在1.48～2.27GPa之间。     

三元共聚聚酰亚胺结构胶的合成及性能研究

以2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)和4,4′-二氨基二苯甲烷(MDA)作为二胺单体,3,3′,4,4′-二苯酮四酸二酐(BTDA)作为二酐单体,N-甲基砒咯烷酮(NMP)为溶剂,通过常规的两步法经热亚胺化合成了三元共聚型聚酰亚胺结构胶。采用傅里叶变换红外光谱表征了聚合物的结构;热重-差热分析(TG-DTA)表明,所合成的聚酰亚胺具有良好的热稳定性,在N2气氛中起始降解温度接近500℃,800℃质量保持率大于50%。单搭接拉伸剪切测试结果表明,所得聚酰亚胺结构胶对不锈钢片的室温粘接强度(LSS)高达14.13MPa,350℃下的拉伸剪切强度达1.91MPa。     

共缩聚聚酰胺酸与聚酰亚胺的微波辐射合成及荧光性能

研究了4,4′-二氨基二苯砜(DDS)、4,4′-二氨基二苯醚(ODA)与均苯四酸二酐(PMDA)的微波辐射溶液聚合反应,将所得的聚酰胺酸进行固相微波辐射亚胺化,并与热聚合进行比较,用红外及核磁共振的测试方法对聚合物的结构进行了表征。结果表明,微波辐射能提高缩聚物的特性粘数和转化率。固相微波辐射使聚酰胺酸的亚胺化时间缩短,亚胺化度增大。合成的聚酰胺酸和聚酰亚胺都具有较强的荧光性能。     

含氟-吡啶环聚酰亚胺的合成与性能

用4-苯基-2,6-双[3-(4-氨基-2-三氟甲基苯氧基)苯基]吡啶(m,p-6FPAPP)作为二胺,3,3′,4,4′-二苯酮四甲酸二酐(BTDA)及2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐(BPADA)作为二酐,以N,N-二甲基甲酰胺(DMF)为溶剂,通过常规的两步法,合成了可溶性含氟聚酰亚胺。用FT-IR、DSC、TGA、UV-vis、溶解性和吸水率测试对聚合物的结构和性能进行了表征。结果表明,FT-IR测试在1780 cm-1、1720 cm-1和1380 cm-1左右出现了聚酰亚胺的特征吸收峰。所得聚酰亚胺在常见溶剂(如间甲酚,DMF,N,N-二甲基乙酰胺(DMAc),二甲基亚砜(DMSO),N-甲基吡咯烷酮(NMP),四氢呋喃(THF))中可溶解;在氮气氛中,玻璃化转变温度(Tg)为202.1℃~219.7℃,10%失重温度为537.0℃~572.8℃,800℃质量保持率为60.7%~63.1%。PI膜的紫外截止波长为375 nm~380 nm,吸水率为0.55%~0.63%。     

含有氢键的聚酰亚胺薄膜的制备和性能表征

以对硝基苯甲酸为原料,通过酰氯化、酰化、还原反应成功合成了4,4’-二氨基苯酰替苯胺(DBN),DBN分别和3,3’,4,4’-联苯四酸二酐(BPDA)、均苯四甲酸二酐(PMDA)通过两步法缩聚制备出聚酰亚胺薄膜,用红外(FT-IR),差示扫描量热仪(DSC)和热重分析(TGA),拉伸测试表征其结构和性能,结果表明,成功合成了含有酰胺键的聚酰亚胺薄膜,并且酰胺键的N-H分别和酰亚胺环中的C-N和C=O形成了氢键。将其与4,4’-二氨基二苯醚(ODA)聚酰亚胺薄膜相比,对应二酐(BPDA和PMDA)分别和DBN制备的聚酰亚胺薄膜表现出了优异的热性能和耐溶剂性,尤其是拉伸强度有了显著的提高。     

共缩聚含吡啶环聚酰亚胺的合成与表征

在微波辐射条件下,由一种新型的含吡啶环二胺(PBAP)和4,4′-二胺基二苯醚(ODA)作为混合二胺分别与三种二酐经"两步法"反应制得一系列共缩聚含吡啶环的聚酰亚胺。借助红外光谱(FT-IR)和核磁共振(1H-NMR)对所得聚酰亚胺的结构进行表征,利用热重分析(TGA)、溶解性能试验、紫外-可见光光谱以及荧光光谱对聚合物的性能进行测试。结果发现,通过共缩聚的方法在聚酰亚胺分子链中引入了芳香吡啶杂环、大的苯环侧基和柔性的二苯醚桥联结构,使其在保持优异的热稳定性(N2中的T10%在520℃以上)的同时,进一步提高了其溶解性能,并具有一定的光学活性。     

溶液缩聚法制备聚酰亚胺绝缘膜及性能研究

以联苯四酸二酐(BPDA)和4,4’-二氨基二苯醚(ODA)为单体原料,利用溶液缩聚法制备聚酰亚胺(PI)绝缘膜,采用XRD、SEM、FT-IR对不同热亚胺化温度合成的PI薄膜结构和表面形貌进行了表征,利用超高阻微电流测试仪测试了热亚胺化温度和粉体含量对PI绝缘膜击穿场强的影响。结果表明,在真空度为1.0×10-2Pa条件下,300℃热亚胺化1h,聚酰亚胺酸(PAA)薄膜完全被热亚胺化,制备的PI绝缘膜内部结构致密;当BPDA和ODA的粉体含量为5%时,PI绝缘膜击穿场强高达2.15MV/cm,表明PI薄膜具有良好的电学性能。     

环丁烷基聚酰亚胺液晶取向膜的制备及光控取向研究

采用1,2,3,4-环丁烷四酸二酐(CBDA)分别与芳香族二胺单体,包括4,4′-二氨基二苯甲烷(MDA)、3,3′-二甲基-4,4′-二氨基二苯甲烷(DMDA)、3,3′,5,5′-四甲基-4,4′-二氨基二苯甲烷(TMMDA)、3,3′-二甲基-5,5′-二乙基-4,4′-二氨基二苯甲烷(DMDEDA)、1,1-双(4-氨基-3,5-二甲基苯基)-1-苯基甲烷(PTMDA)以及1,1-双(4-氨基-3,5-二甲基苯基)-1-(3′-三氟甲基苯基)甲烷(TFMDA)通过低温溶液缩聚法制备了聚酰胺酸(PAA)型液晶取向剂。采用该系列PAA取向剂装配了液晶盒。测试结果显示,PAA高温固化后形成的聚酰亚胺(PI)取向膜具有良好的耐热稳定性,5%失重温度均超过了450℃。经过波长为254 nm的线性偏振紫外光(LPUV)辐照后,该系列PI取向膜对液晶分子具有良好的取向效果,预倾角(θ_p)为0.28～0.47°。装配的液晶盒的残余直流电压(RDC)最低可达364 mV。     

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.     

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 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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.