环三磷腈基苯并噁嗪的合成及热性能研究

为提高苯并噁嗪树脂的耐高温性能,以水杨醛、对氨基苯酚、环三磷腈衍生物为原料通过多步反应制备了环三磷腈基苯并噁嗪单体(CPBOZ),通过核磁共振(1 H-NMR、31 P-NMR)和傅里叶红外光谱(FT-IR)对所合成化合物的结构进行了表征;利用FT-IR和热重分析(TGA)考察了苯并噁嗪的固化行为及树脂的热稳定性。结果显示:环三磷腈结构的引入,显著提高了相应苯并噁嗪树脂的耐热性,其固化后失重率为5%和失重率为10%时的温度分别达到了365℃和397℃;在900℃(N2)时的失重率达到了48.2%,比普通苯并噁嗪树脂提高了约65.64%。     

含8-羟基喹啉结构聚苯并噁嗪的合成及性能

以8-羟基喹啉、苯胺和多聚甲醛为原料,采用溶液法合成新型苯并噁嗪单体3,4-二氢-3-苯基-2氢-1,3-苯并噁嗪基-(5,6-h)喹啉(QB)。QB的化学结构采用傅里叶变换红外光谱、核磁共振氢谱和碳谱、质谱进行表征,并封管聚合得到含8-羟基喹啉结构的聚苯并噁嗪(PQB)。差示扫描量热、热失重和凝胶渗透色谱测试结果表明,与传统的苯并噁嗪相比,QB开环聚合温度降低,聚合峰值温度为216.2℃,且咪唑可以进一步降低QB的聚合温度。210℃聚合4h所得到的聚合物PQB2在850℃时残炭率(Yc)为31.9%,由于聚合物结构中含有喹啉等刚性基团使聚合物具有较好的热稳定性。PQB2的珨Mn,珨Mw和PDI分别为11300,12000和1.06。     

聚酰胺650对苯并噁嗪开环聚合和固化物性能的影响

制备了聚酰胺650(O-PA)/苯并噁嗪混合体系并测试凝胶化时间、差示扫描量热分析(DSC)和傅里叶变换红外光谱(FTIR),以研究O-PA对苯并噁嗪开环聚合和韧性的影响。结果表明,O-PA能促进苯并噁嗪的开环聚合反应,使其凝胶化时间、开环聚合的起始和峰值温度明显降低,但是不影响苯并噁嗪开环聚合过程中的结构演变和聚苯并噁嗪的化学结构。O-PA的引入使聚苯并噁嗪的韧性明显提高,但是热稳定性有所降低。结果表明,聚酰胺650是一类良好的苯并噁嗪催化剂。     

含双螺环取代三聚磷腈结构苯并口恶嗪树脂的合成与性能

以六氯环三聚磷腈,1,1′-二羟基联苯,对羟基苯甲酸乙酯和含活泼官能团的苯并口恶嗪单体为原料合成了含双螺环取代三聚磷腈结构的苯并口恶嗪单体(HCP)。采用FT-IR,1 H-NMR,13 C-NMR,和31P-NMR进行了表征,并研究了其固化行为以及HCP均聚物和HCP与双酚A苯并口恶嗪树脂(Bz)共聚物的热性能。结果表明,HCP均聚物在氮气氛下的起始热分解温度为333℃,800℃时残炭42%。HCP/Bz共聚物的起始热分解温度为367℃,800℃残炭率达52%,具有比HCP和Bz均聚物更好的热稳定性和成炭性能。     

氢氧化铝改性苯并噁嗪及阻燃性的研究

以加入氢氧化铝(ATH)提高苯并噁嗪树脂(BOZ)的阻燃性,并对阻燃聚苯并噁嗪树脂的性能进行研究.结果表明,当氢氧化铝质量分数大于20%时,聚苯并噁嗪树脂的阻燃性可以达到UL-94V0级.差示扫描量热(DSC)和动态机械分析(DMA)测试显示氢氧化铝的加入,使苯并噁嗪树脂开环固化反应放热热焓和峰值温度均有降低,使聚苯并...     

耐高温聚苯腈树脂的制备及性能

以芳香二酚(间苯二酚、2,7-二羟基萘、1,6-二羟基萘)、2,6-二氯苯腈和4-硝基邻苯二甲腈为主要原料制备了6种耐高温低熔点型苯腈单体,并利用4,4’-二氨基二苯醚引发聚合。采用红外光谱、核磁共振、差示扫描量热、热重分析、动态机械分析表征了单体和聚合物的结构及性能。结果表明,所合成的苯腈单体产物纯净,熔点在90℃~116℃,加工温度窗口为125℃~155℃。所制备聚苯腈树脂的起始分解温度(Tid)都高于460℃,有限氧指数(LOI)均高于47,表现出了良好的加工性、高阻燃性、优异的热稳定性及高玻璃化转变温度(>380℃)。     

含柔性长链的全生物基苯并噁嗪的合成及性能EI北大核心CSCD

以腰果酚、漆酚、糠胺和多聚甲醛为原料合成了含柔性长链的全生物基苯并噁嗪单体(CFa和UFa),再通过热固化得到柔性聚苯并噁嗪片材(PCFa和PUFa)。利用红外光谱(FT-IR)和核磁共振(1 H-NMR)对CFa和UFa的化学结构进行了表征,同时比较了其热固化行为、形成柔性片材的能力及对应聚苯并噁嗪的热性能、动态力学性能和吸水性能。FT-IR和差示扫描量热分析(DSC)结果表明,在高温时,CFa和UFa发生了开环聚合反应,且UFa比CFa开环聚合的温度低。通过动态力学热分析(DMA),PCFa和PUFa的玻璃化转变温度分别为85℃和143℃,储存模量分别为203.2MPa和510.7MPa。PCFa和PUFa热失重5%时的温度分别为372℃和395℃。在不同pH环境中,PUFa片材比PCFa片材具有更低的吸水率。     

含柔性长链的全生物基苯并噁嗪的合成及性能

以腰果酚、漆酚、糠胺和多聚甲醛为原料合成了含柔性长链的全生物基苯并噁嗪单体(CFa和UFa),再通过热固化得到柔性聚苯并噁嗪片材(PCFa和PUFa)。利用红外光谱(FT-IR)和核磁共振(1 H-NMR)对CFa和UFa的化学结构进行了表征,同时比较了其热固化行为、形成柔性片材的能力及对应聚苯并噁嗪的热性能、动态力学性能和吸水性能。FT-IR和差示扫描量热分析(DSC)结果表明,在高温时,CFa和UFa发生了开环聚合反应,且UFa比CFa开环聚合的温度低。通过动态力学热分析(DMA),PCFa和PUFa的玻璃化转变温度分别为85℃和143℃,储存模量分别为203.2MPa和510.7MPa。PCFa和PUFa热失重5%时的温度分别为372℃和395℃。在不同pH环境中,PUFa片材比PCFa片材具有更低的吸水率。     

磷钨酸对苯并■嗪开环聚合历程的影响

在室温下首先制备了磷钨酸/苯酚-苯胺型苯并■嗪(Pa)混合体系,然后通过傅里叶变换红外光谱、核磁共振氢谱、差示扫描量热分析研究了磷钨酸(PWA)对Pa开环聚合过程的影响。测试结果表明,由于磷钨酸中氢离子、钨原子与Pa中氧原子的相互作用,不仅使得Pa开环聚合起始温度和峰值温度随磷钨酸的引入而明显降低,甚至在室温下也可促使Pa开环聚合。通过Kissinger和Ozawa法对苯并■嗪固化动力学进行了研究,结果表明Pa开环聚合反应活化能随磷钨酸的引入而降低,进一步证明磷钨酸对苯并■嗪开环聚合有促进作用。此外,磷钨酸还使得Pa开环聚合过程中形成的碳正离子中间体与苯胺对位反应的几率增加,形成了更多的1,4-二取代芳胺结构,抑制了热降解过程中苯胺结构的挥发。以对甲酚-苯胺型苯并■嗪为模型的GPC测试表明,磷钨酸还可使聚苯并■嗪的相对分子质量有所增加。另外,热重分析结果表明Pa聚合物的热稳定性随磷钨酸的加入而增加。     

腰果酚型苯并噁嗪的固化特性

以腰果酚、幕胺、甲醛为原料,合成了腰果酚型苯并噶嗪单体.采用红外光谱(FT-IR)、差示扫描量热分析(DSC)、动态热机械分析(DMA)和热失重分析(TGA)对其热聚合和加入自由基引发聚合两种情况下的固化行为及固化物结构和性能进行了研究.结果表明,腰果酚型苯并噁嗪热开环聚合形成的固化物是T<,g>为137℃的塑料;加入...     

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.