水溶液中聚乙烯基吡咯烷酮与十二烷基硫酸钠的相互作用机理

利用黏度、电导、表面张力和荧光光谱实验手段研究了聚乙烯基吡咯烷酮(PVP)和十二烷基硫酸钠(SDS)在水溶液中的相互作用,发现对SDS来说存在三个不同的特征浓度:临界聚集浓度(CAC)、CAC2和高分子饱和浓度(PSP)。实验结果表明,PVP和SDS在水溶液中的相互作用可以用类似于描述聚电解质和带相反电荷表面活性剂之间相互作用的两阶段模型解释:初始阶段(CSDS>CAC),带负电荷的SDS分子主要以单个的方式吸附到PVP带正电的侧基上;第二阶段(CSDS>CAC2),SDS分子通过疏水相互作用以协同的方式吸附到PVP分子链上形成胶束,在浓度为PSP时达到饱和。     

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。     

梳状结构硅表面活性剂的溶液性质

采用氢硅化法制备得到了一系列具有梳状结构的非离子有机硅表面活性剂(PESO)。利用红外光谱和核磁共振氢谱对产物的结构进行了表征,分析了疏水基团的含量对PESO表面活性剂表面张力和临界胶束浓度的影响,研究了PESO表面活性剂在水溶液表面的吸附现象及在水溶液中的聚集行为,探讨了其在水溶液中形成的胶束的尺寸和分布。研究表明,随着疏水组分含氢硅油(PHMS)含量的增加,PESO表面活性剂分子越易缔合形成胶束且胶束的平均粒径增大。当PHMS含量由25%增加至67%时,临界胶束浓度(CMC)由0.828 g/L降至0.613 g/L,γCMC可降至22.11 mN/m,表面吸附量(Γ)可达3.31μmol/m2,每个表面活性剂分子吸附在空气/水界面的平均面积(A)仅为0.502 nm2,PESO表现出较好的表面活性。此外,荧光光谱法研究PESO聚合物在水溶液中的聚集行为发现,随着表面活性剂浓度的增加,第一、第三发射峰的荧光强度比值(I1/I3)不断减小,达到PESO的临界缔合浓度后,芘分子增溶于PESO胶束中,I1/I3趋于恒定。     

温敏性聚合物P（AM-Macromer）及其与表面活性剂的复合性能

以含氧乙基结构的烯类单体(Macromer)和丙烯酰胺(AM)为原料,制备了具有温度敏感性的疏水缔合水溶性共聚物P(AM-Macromer).研究了P(AM-Macromer)溶液与不同表面活性剂的相互作用.结果表明,P(AM-Macromer)在水溶液中与表面活性剂存在明显相互作用,复合效应与聚合物浓度、表面活性剂结构及浓度有关.在较高浓度聚合物溶液中,少量表面活性剂的加入能显著提高溶液的黏度;在低浓度聚合物溶液中,表面活性剂的加入使溶液表观黏度下降.表面活性剂对共聚物P(AM-Macromer)溶液黏度的影响强弱顺序为:SDBSCTABOP-10.     

疏水改性PNIPA水凝胶的制备及在表面活性剂溶液中的性能

采用水溶液和水溶液胶束自由基聚合方法分别制备了聚N-异丙基丙烯酰胺水凝胶(PNIPA)和疏水改性PNIPA水凝胶：聚N-异丙基丙烯酰胺-co-丙烯酸甲酯(MA)／丙烯酸乙酯(EA)／丙烯酸丁酯(BA)／丙烯酸十二酯(DA)水凝胶。研究了凝胶的微观结构及不同结构的水凝胶在表面活性剂溶液中的溶胀行为。结果表明,PNIPA与疏水改性PNIPA水凝胶有着不同的微观形态结构;与PNIPA水凝胶相比,疏水改性PNIPA水凝胶在十二烷基硫酸钠(SDS)和十六烷基三甲溴化铵(CTAB)水溶液中的溶胀率增大,温敏性增强。疏水改性水凝胶在溶液中的溶胀行为与凝胶化学结构、溶液组成有关。对于疏水改性丙烯酸酯-NIPA共聚水凝胶,其溶胀率随丙烯酸酯碳链长度的增加而降低,在SDS溶液中的相转变温度远比CTAB溶液中的高,突变温度区间更宽。     

梳型丙烯酰胺共聚物在水溶液中的缔合结构

采用荧光探针研究了丙烯酰胺(AM)/4-乙烯苄基辛烷基酚聚氧乙烯(10)醚(VBPOE)/2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)梳型共聚物(PAVA)在水溶液中的疏水缔合微结构。结果发现,在纯水和盐水溶液中,随聚合物浓度的增大,疏水微区的数量和非极性明显增加,但当PAVA浓度高于0.20 g/dL时,疏水微区的非极性趋于恒定,而且0.5 g/dLNaCl的加入对I1/I3值(I1/I3的变化可以表征疏水微区是否形成以及监测疏水缔合微区的变化)的影响极小,这证实了分子链在盐水中的构象仍然较伸展,使得PAVA在盐水中也能形成连续的缔合结构,从而赋予聚合物良好的抗盐和增粘性能。随着盐浓度的增加,缔合微结构的非极性变化不大,但其紧密度和数量增加,Ie/Im值持续增大。     

AM-STD-NaAMPS三元疏水缔合共聚物的表征及耐热性能

以自制的疏水单体苯乙烯衍生物(STD)和丙烯酰胺(AM)、2-甲基-2-丙烯酰胺基丙磺酸钠(NaAMPS)为原料,合成了三元疏水缔合水溶液共聚物PASA。用红外光谱、核磁共振1H谱和DSC分析证实了共聚物的结构,采用元素分析测定了聚合物的组成,通过原子力显微镜对聚合物溶液形态的表征,证实了PASA水溶液疏水微区的存在。TG分析显示PASA具有优良的耐热性能,其分解温度高达312℃。PASA浓度为0.1g/dL时,表观粘度达208mPa.s,表明了其聚合物具有优良的增粘能力。     

含氟丙烯酰胺共聚物的合成及性能

为制备性能较好的疏水缔合聚合物,以1H,1H,2H,2H-十七氟癸烷丙烯酸酯(HFA)为疏水单体,以丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为水溶性单体,采用胶束聚合法合成了含氟丙烯酰胺共聚物(FPAM)。使用红外、荧光、扫描电镜等方法对FPAM结构进行表征,研究了FPAM的耐温、抗盐及抗剪切性能。结果表明,聚合产物结构与疏水单体加量有关,在聚合体系中加入含氟疏水单体后,聚合产物的相对分子质量降低;FPAM中HFA单体结构单元含量先随HFA加量的增加而增大,由于含氟疏水单体的空间位阻效应,当HFA质量分数大于0.4%之后变化趋势变缓。FPAM聚合物中含有HFA强疏水性单体结构单元,在水溶液中会发生疏水缔合作用,到达一定浓度后会形成超分子聚集体,FPAM的临界缔合浓度为300~400mg/L,与相对分子质量较高的丙烯酰胺-2-丙烯酰胺基-2-甲基丙磺酸共聚物相比,含氟疏水缔合聚合物FPAM具有更强的增黏能力和更好的耐温、抗盐及抗剪切性能,可望用于油气开采领域。     

两亲嵌段疏水缔合聚合物基纳米SiO_2的合成及溶液特性

以丙烯酰胺(AM)、2-丙烯酰胺-2-甲基丙磺酸钠(AMPS)、马来酸酐(MA)和纳米二氧化硅为亲水单体,苯乙烯(St)为疏水单体,十二烷基硫酸钠(SDS)为乳化剂,采用微乳液自由基聚合法制备了一种具有疏水缔合结构的聚合物基纳米二氧化硅复合材料。通过红外光谱、透射电镜、扫描电镜、粒径分布测试和凝胶渗透色谱法表征了聚合物纳米材料的分子结构和相对分子质量,探讨了聚合物基纳米二氧化硅在水溶液中疏水缔合特性,增粘性,抗温、耐温性及耐盐性能的影响规律。结果表明,当聚合物分子中含有1%的苯乙烯单体时,聚合物有较好的疏水缔合作用,纳米二氧化硅的引入可使聚合物分子在水溶液中产生特殊的微交联结构,且增粘性及热稳定性得到改善明显,复合材料热分解温度约为290℃,在室温至500℃范围内该材料的热失重总量仅为60%。     

荧光探针研究温敏大分子单体在水溶液中的热缔合行为

通过芘荧光探针研究了基于双丙酮丙烯酰胺(DAAM)的新型温敏大分子单体在溶液中的热缔合行为。结果表明,温敏大分单体的临界缔合浓度(CAC)取决于丙烯酰胺(AM)与DAAM的组成比。DAAM的比例越大,CAC就越低;随着温敏大分子单体中DAAM的含量、大分子单体浓度和溶液pH的增加,芘的I1/I3值降低,疏水缔合作用增强,且温度越高,I1/I3值越低,呈现明显的热缔合行为。温敏大分单体的热缔合行为随组成、浓度和pH变化的这种性质有可能在新型温敏聚合物及凝胶的合成设计上获得应用。     

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.