A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation

Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.     

Visualization and quantification of the mechanical deformation induced by an electrical field in poly(ethylene naphthalene 2,6‐dicarboxylate) (PEN) films

An optical nondestructive strain measurement technique was performed to analyze the mechanical deformation induced by an electrical field within the insulating materials. Poly(ethylene naphthalene 2,6‐dicarboxylate) (PEN) films were then subjected to constant electrical fields right up to their electrical breakdown. The experimental technique made it possible to follow the various stages of the mechanical behavior of PEN in real time. The final breakdown occurred in the observation zone and the related mechanical deformation was captured. A “margarita” structure was observed with a hole at the center. The experimental results indicated that the level of the induced‐mechanical deformations depended on the local environment. We defined two different zones representing the inside and the outside of the damaged area. The induced‐deformations were larger in the damaged zone. It was also observed that deformations increased when the sample had a lower degree of crystallinity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Grafting of maleic anhydride onto polyethylene through a green chemistry approach

The grafting of a polymer can lead to the improvement and modification of the polymer and thus expand its applications. Grafting methods include solution grafting in organic solvents, melt grafting at high temperatures, and light grafting with radioactive sources. These methods have their advantages and disadvantages. The disadvantages include waste treatment, consumption of energy, and so on. In this study, a hydrothermal process which is called the green approach, was developed to prepare graft copolymers. The effect of various factors on the grafting degree was investigated in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

土钉加锚杆联合支护基坑的失稳分析及处理

根据具体工程实例,介绍了在基坑开挖时采用土钉加锚杆的联合支护方式后在施工过程中出现坍塌裂缝的现象,针对这一现象,分析了施工条件与环境,得出了事故发生的原因,并结合实际情况提出了处理措施.     

The effect of aromatics on paraffin mild hydrocracking reactions (WNiPd/CeY–Al2O3)

The conversion of heavy paraffin and aromatics into a high-quality diesel fraction was performed in a microplant using a WNiPd/CeY-alumina catalyst. The effects of aromatics and naphtheno-aromatics on mild hydrocracking of hexadecane were studied at different concentrations. Two catalysts, with and without Pd and thermal treatment, were characterized by FTIR, XPS, and TPD of ammonia and ammonia plus naphthalene to complement previous study about the surface composition. The hydrocracking activity and selectivity were tested using different amounts and types of aromatics. This study demonstrated the presence of two acid strengths that contribute in different ways to paraffin and aromatics isomerization, ring opening, and cracking reactions. The product distribution obtained by mild hydrocracking of n-C₁₆ is between amorphous (SiO₂Al₂O₃) and Y-zeolite type of support. The aromatic adsorption on acid sites reduces the cracking rate and improves the survival of di- and tri-branched paraffin. A model for the path of reaction is discussed to explain the results.     

Isobaric vapor—liquid equilibria for binary systems composed of methyl butanoate with ethanol and with propan-1-ol at 114.66 and 127.99 kpa

Vapor-liquid equilibrium data for the binary systems methyl butanoate/ethanol and methyl butanoate/propan-l-ol at pressures of 114.66 and 127.99 kPa are presented. Both mixtures yield an azeotrope, the compositions (ester) of which decrease quasi-linearly as the pressure increases. The experimental data for all the binary mixtures were fitted to a suitable equation and then used for comparison with predictions by ASOG and UNIFAC methods. These group contribution models give a good estimation of activity coefficients with an overall mean error less than 5% for all cases.     

通过细乳液聚合方法制备自交联型有机硅乳液

苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯(M PS)经细乳液聚合,制得了稳定的自交联型的水分散涂料,用透射电子显微镜(TEM)、动态光散射仪(DLS)和红外光谱(IR)表征了乳胶粒的形态和结构。发现与传统乳液聚合相比,细乳液聚合法可显著提高乳液的稳定性,且M PS加入量的增加会导致乳液稳定性降低。     

酚醛胺(T-31)环氧树脂固化剂之浅谈

介绍了酚醛胺(T-31)系列环氧固化剂及原料的现状和特点,并对酚醛胺(T-31)系列环氧固化剂进行了分代,阐述了第三代酚醛胺(T-31)系列环氧固化剂的系列化、专用化、高档化。预测和展望了2005年的需求和方向。