Atom transfer radical polymerization of n‐butyl methacrylate in an aqueous dispersed system

Atom transfer radical polymerization of n‐butyl methacrylate (BMA) was conducted in an aqueous dispersed system with different kinds of copper complexes. The partitioning behavior of the copper complexes, including CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipydine (dNbpy), CuCl₂/dNbpy, CuCl/2,2′‐bipydine (bpy), CuCl₂/bpy, CuCl/bis(N,N′‐dimethylaminoethyl)ether (bde), and CuCl₂/bde between the monomer (BMA), and water was studied in detail with ultraviolet‐visible spectroscopy. The results show that with a less hydrophobic ligand, such as bpy or bde, most of the Cu(I) or the Cu(II) complexes migrated from the BMA phase to the aqueous phase, the atom transfer equilibrium was destroyed, and the polymerization was nearly not controlled; it converted to classical emulsion polymerization. As to the very hydrophobic ligand dNbpy, although the partitioning study of the copper complexes indicated that not all the copper species were restricted to the organic phase, the linear correlation between the molecular weight and the monomer conversion and the narrow polydispersities confirmed that the polymerization was still quite well controlled. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3175–3179, 2003     

不同紧度下约束满足问题的相变现象

提出了一个基于RB模型的随机约束满足问题即◢p◣-RB模型。该模型考虑了约束紧度的多样性,将所有约束按照不同的权重分成若干组,同一组具有相同的约束紧度,而相异组具有不同的约束紧度。用二阶矩方法严格证明了随着控制参数的不断增加,◢p◣-RB模型发生了精确的可满足性相变现象。数值实验表明该模型的有解概率经历了从1到0的突然转变,同时求解难度在相变区域达到高峰,表明该模型在相变区域能产生大量的难解实例。     

Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process

The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation of Ce(IV) in nitric acid media at 80 °C were studied. The current-voltage curves and cerium electrolysis kinetics showed the dependence on number of cell stacks needed to be connected in series for the destruction of a given quantity of organic pollutant. The presence of an optimum region for Ce(III) oxidation with a contribution of oxygen evolution, especially at low Ce(III) concentration (high conversion ratios), was found. The cells were applied for the Ce(IV) regeneration during the organic destruction. The cell and reactor processes were fitted in a simple model proposed and used to calculate the current needed in terms of Ce(III) oxidation rate and the number of cell stacks required for maintaining Ce(IV)/Ce(III) ratio at the same level during the organic destruction. This consideration was based on the kinetic model previously developed by us for the organic destruction in the MEO process.     

Molecular weight distribution of polyethylene catalyzed by Ziegler–Natta catalyst supported on MgCl2 doped with AlCl3

Ti‐based Ziegler–Natta catalysts supported on MgCl₂ doped with AlCl₃ were prepared by the reaction of MgCl₂/AlCl₃–ethanol adduct with TiCl₄. No AlCl₃ crystallites were found in the AlCl₃‐doped catalysts by WAXD analysis, suggesting that AlCl₃/MgCl₂ solid solution was formed. The effect of doping on the catalyst performance in ethylene polymerization was investigated. The results showed that the catalysts based on AlCl₃‐doped MgCl₂ support exhibited a slightly higher activity than did the MgCl₂‐supported catalyst and the molecular weight distribution (MWD) of polyethylene (PE) markedly increased (from 10.8 to 47.9) with the increase of AlCl₃ content in catalysts. The changes in catalyst's active center distribution were studied based on nonlinear fitting of the polymer GPC curves by multiple Flory functions. It was found that increase of types of active centers by introducing AlCl₃ into the support should be responsible for the broadening of MWD of PE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1768–1772, 2006     

Controlled coagulation of emulsion polymers

Coagulation of latex particles is most often carried out in the diffusion limited aggregation (DLA) regime where the time for coagulation to take place is on the millisecond timescale. This process produces aggregates of low density, irregular shape, and a broad particle size distributions. When the coagulation is carried out in the reaction limited aggregation (RLA) regime, a coagulation time of about 1–120 sec, the system can be controlled by mixing to yield dense, spheroidal aggregates with a very narrow particle size distribution. The important variables in the RLA process for butyl acrylate/methyl methacrylate (BA/MMA) latexes were found to be mixing intensity, latex copolymer composition, and coagulation temperature. Dried aggregates formed in the RLA process were found to have excellent powder flow properties and low dustiness.     

几种农药对芒果树白蛾蜡蝉的药效试验

比较测定了10%吡虫啉可湿性粉剂、20%好年冬乳油和48%乐斯本乳油等3种药剂在常规用量下对芒果上发生的白蛾蜡蝉的防治效果。结果表明,乐斯本1000倍液和好年冬1500倍液对白蛾蜡蝉具有较好的速效性,药后1 d的防效分别为80.44%和73.98%;吡虫啉2000倍液对白蛾蜡蝉具有较好的持效性,药后7 d的防效仍然达79.61%;认为使用吡虫啉防治白蛾蜡蝉的适宜浓度为1500~2000倍。     

共混改性SEBS体系的研究进展

介绍了热塑性弹性体SEBS的性能：综述了通过共混改性的SEBS弹性体体系的性能与形态结构的研究进展。     

一体化锅炉水处理剂的制备及性能研究

利用自制SW-56共聚物，复配有机磷酸盐和焦亚硫酸钠除氧剂及消泡剂，成功制备XF-4一体化锅炉水处理剂。对XF-4锅炉水处理剂的阻垢、缓蚀进行了试验研究，表明其具有优良的阻垢能力，可以明显抑制热水锅炉积垢现象；加入改性除氧剂能降低锅炉水中溶解氧的含量，使腐蚀控制较理想；配方中的消泡剂组分可防止锅炉水表面起泡，抑制高悬浮物下的携带作用。     

Reaction kinetics study of asymmetric polymer-polymer interface

In this study, the reaction kinetics of asymmetric polymer-polymer interface was experimentally and theoretically studied. A new rheological method correlating the change of rheological property of reactive system with the conversion of the in situ formed copolymers was applied to study the reaction kinetics of PBT/epoxy reactive system. Then, the new method was proved to be useful by comparing its results with that obtained from the conventional endgroup determination method. Moreover, the conversion of PBT/epoxy reactive system from rheological method could be well fitted by the numerical analysis, from which the kinetic constant and the diffusion constant of epoxy in PBT could be determined simultaneously.     

全自动液压压砖机CAD/CAE信息集成系统数据库的研究与开发

对全自动液压压砖机CAD CAE信息集成系统中的工程数据库的设计和实施进行了研究 ,分析了系统对数据信息的需求 ,提出了该系统数据库的E -R数据模型以及表的定义和结构关系 ,实现了压砖机CAD CAE信息集成系统。