疏水改性聚合物P(AM/AA/POEA)的溶液性质

应用黏度法研究了新型缔合聚合物P(AM/AA/POEA)的溶液流变性质。该聚合物由丙烯酰胺(AM)、丙烯酸(AA)和少量2-苯氧乙基丙烯酸酯(POEA)组成。结果表明,共聚物中疏水嵌段的数量、长度和离子基团含量对溶液流变性质有重要影响,这种离子型聚合物的溶液性质同时受疏水基团的缔合作用和离子基团间的静电排斥作用的共同影响。同时进一步研究了聚合物浓度和pH值对溶液黏度的影响。研究结果表明,这类聚合物在较宽pH值范围黏度较高,说明在实际应用中可操作的范围较宽。     

阴离子长链疏水缔合水溶性聚合物的合成及溶液性能

利用溶液聚合制备了离子型疏水缔合水溶性共聚物P(AM/AMPS/C11AM),在共聚物结构中引入了既带有疏水长链又带有可离子化的基团,红外光谱确认了所合成的共聚物为目标共聚物;P(AM/AMPS/C11AM)系列共聚物溶液的表观黏度与共聚物浓度有很大关系,即使在极低的共聚物溶液浓度下也具有很好的增粘效果;在一定温度,一定pH值和表面活性剂的条件下,研究了系列共聚物溶液行为,结果与接枝疏水单体改性的丙烯酰胺是不同的。荧光光谱研究证实了共聚物在水溶液中的缔合行为。     

疏水改性丙烯酰胺共聚物在水溶液中的缔合

罗丹明B荧光探针发现丙烯酰胺(AM)/丁基苯乙烯(BST)/2-甲基-2-丙烯酰胺基丙磺酸钠(NaAMPS)共聚物(PASA)在0.05 g/dL水溶液中疏水微区的黏度已较大,说明PASA具有强的疏水缔合效应。动态光散射结果表明,PASA在0.005 g/dL极稀溶液中,主要以单分子存在,部分单分子链发生了分子内缔合;在0.01 g/dL~0.2 g/dL范围内,溶液中均有构象伸展和卷曲的单分子存在,粒径有单分子区和疏水缔合区;当共聚物浓度增加为0.3 g/dL时,流体力学半径分布为单分散,只有缔合体存在。随着分子中疏水链段含量的增加,0.1 g/dL PASA溶液的疏水缔合体(Rh:2800 nm~5000 nm)的数量增加,溶液黏度显著升高。     

一种疏水缔合丙烯酰胺共聚物的合成及流变性能评价

采用自由基胶束共聚法以丙烯酰胺(AM)和N-苄基-N-辛基丙烯酰胺(BOAM)为原料,合成了疏水缔合共聚物(AM-NaA-BOAM),并用红外光谱(FT-IR)和核磁共振(1H-NMR)表征了共聚物的结构.溶液的流变性实验表明,当共聚物浓度大于600 mg/L时,表现黏度显著增大,表现出疏水缔合行为,溶液的储能模量(G...     

AM/NVP二元共聚物的溶液性能

采用自由基水溶液共聚法制备了丙烯酰胺／N-乙烯基吡咯烷酮二元共聚物(AM／NVP),使用旋转黏度计测定了共聚物水溶液的表观黏度,详细研究了聚合物浓度、聚合物组成、电解质浓度、温度、剪切速率、表面活性荆浓度等因素对聚合物溶液表观黏度的影响。结果表明,丙烯酰胺／N-乙烯基吡咯烷酮二元共聚物的水溶液具有一定的疏水缔合作用,聚合物溶液具有一定的耐温性和耐盐性。     

基于聚醚的热增黏接枝聚合物的合成及性能

聚合物水溶液黏度通常会随温度升高而降低。为了解决高温下聚合物溶液的增黏难题,文中利用聚醚(F127)分别与丙烯酸、丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸接枝共聚,得到了系列热增黏聚合物。考察了聚合条件、聚合物浓度、亲水单体的性质对聚合物溶液热增黏能力的影响。结果表明,聚合物浓度越高、聚合物相对分子质量越高,聚合物的热增黏性能越好,热缔合温度也越低。     

含大单体四元共聚物的盐诱导增粘和缔合行为EI北大核心CSCD

针对驱油聚合物难以应用于高盐油藏的难题,合成了新型大单体烯丙基辛基酚聚氧乙烯(20)醚(APE),将其与丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)和4-乙烯基联苯(VP)共聚,获得了抗盐共聚物PSA。PSA显示了优异的由盐诱导的增粘性能,在70.00g/L NaCl中的临界缔合浓度只有0.3g/L;当NaCl浓度高于40.0g/L后,溶液黏度反而比纯水中的黏度高得多,且随着NaCl浓度的增加急剧上升。探针分析以及原子力显微镜结果显示,PSA分子链在纯水中的构象伸展,通过分子间疏水缔合作用形成了分子链束,高盐的加入使缔合作用显著加强,溶液黏度急剧上升。     

含大单体四元共聚物的盐诱导增粘和缔合行为

针对驱油聚合物难以应用于高盐油藏的难题,合成了新型大单体烯丙基辛基酚聚氧乙烯(20)醚(APE),将其与丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)和4-乙烯基联苯(VP)共聚,获得了抗盐共聚物PSA。PSA显示了优异的由盐诱导的增粘性能,在70.00g/L NaCl中的临界缔合浓度只有0.3g/L;当NaCl浓度高于40.0g/L后,溶液黏度反而比纯水中的黏度高得多,且随着NaCl浓度的增加急剧上升。探针分析以及原子力显微镜结果显示,PSA分子链在纯水中的构象伸展,通过分子间疏水缔合作用形成了分子链束,高盐的加入使缔合作用显著加强,溶液黏度急剧上升。     

疏水改性聚丙烯酰胺P(AM/DiC_8AM)的合成及性能

采用二元单体胶束共聚,合成了孪尾疏水改性丙烯酰胺/N,N-二辛基丙烯酰二元共聚物[简称P(AM/DiC8AM)],成功引入了疏水单体.用FTIR分析了各基团峰的归属,证明了共聚物为带有疏水基团的二元共聚物.特性粘数的测定结果表明:分子量M、疏水单体含量[H]增加,特性粘数[η]增大,Huggins常数KH减少,平均线团密度ρequ减少;但随疏水链嵌段长度NH的增加,[η]们增大,KH同样增大.随疏水单体含量[H]、分子量M、疏水链的嵌段长度NH增加,各聚合物溶液临界缔合浓度cac降低,疏水缔合的机率增加.     

非离子型疏水缔合聚合物PBAM的溶液性能

由丙烯酰胺和N-苯基对烷基丙烯酰胺采用水溶液自由基胶束聚合法合成疏水缔舍聚合物PBAM。研究了共聚物浓度、盐浓度、温度及表面活性剂浓度对共聚物溶液粘度的影响。结果表明,当聚合物的浓度大于临界缔合浓度时溶液的粘度怠剧增加;NaCl的加入使得溶液的粘度下降,但适当结构的聚合物表现出较好的抗盐能力;聚合物浓度恒定时,溶液粘度随表面活性剂SDS浓度的增加急剧增加,达到最大值后迅速下降。聚合物稀溶液的流变行为呈现牛顿流体的性质。     

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.