Preparation of hyperbranched polymers by atom transfer radical polymerization

A cheap acrylic AB* monomer, 2‐(2‐chloroacetyloxy)‐isopropyl acrylate (CAIPA), was prepared from 2‐hydroxyisopropyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self‐condensing vinyl polymerization by atom transfer radical polymerization (ATRP), a “living”/controlled radical polymerization, has yielded hyperbranched polymers. All the polymerization products were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR). CAIPA exhibited distinctive polymerization behavior that is similar to a classical step‐growth polymerization in the relationship of molecular weight to polymerization time, especially during the initial stage of the polymerization. However, a significant amount of monomer remained present throughout the polymerization, which is consistent with typical chain polymerization. Also, if a much longer polymerization time was used, the polymer became gel. As a result of the unequal reactivity of group A* and B*, the polymerization is different from an ideal self‐condensing vinyl polymerization: the branch structures of polymers prepared depend dramatically on the ratio of 2,2'‐bipyridyl to CAIPA. Hyperbranched polymers exhibit improved solubility in organic solvent, however, they have lower thermal stability than their linear analogs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2114–2123, 2002     

EFFECT OF PORE DIFFUSION ON DEACTIVATING RATES OF SECOND ORDER REACTION

The research and development of catalysts, the design and operation of catalytic reactors are complicated by the phenomenon of catalyst deactivation which is affected by various factors. In this paper, the effect of internal mass transfer resistance in the second order catalytic reaction system of uniform independent deactivation on both reaction and deactivation rates of straight cylindrical pore model has been discussed. In addition, the quantitative relations between effectiveness factor and Thiele modulus in second order reaction and first order deactivation system have been correlated     

Data acquisition system for chemical kinetic studies

A microcomputer-interfaced data acquisition system for chemical kinetics (interfacing with laboratory analogue instruments) has been developed. Analogue signals from instruments used in kinetics experiments are amplifed by a wide-range adjustable high-gain operational amplifier and smoothed by an op-based filter, and then digitized at rates of up to 10⁴ samples per channel by an ADC 0816 digitizer. The ADC data transfer and manipulation routine was written in Assembler code and in high-level language; the graphics package and data treatment package is in Basic. For the various sampling speeds, all of the program can be written using Basic-Assembler or completely in Assembler if a high sampling rate is needed. Several numerical treatment methods for chemical kinetics have been utilized to smooth the data from experiments.The computer-interfaced system for second-order chemical kinetic studies was applied to the determination of the rate constant of the saponification of ethyl acetate at 35°C. For this specific problem, an averaging treatment was used which can be called an interval method. The use of this method avoids the diffcully of measuring the starting time of the reaction. Two groups of experimental data and results were used to evaluate the systems performance. All of the results obtained are in agreement with the reference value.     

基于Simulink环境的壳管式换热器动态特性的分析

壳管式换热器在化工和食品行业中有着广泛的应用,对其分析的方法与手段也有很多。在本文中,作者尝试建立起壳管式换热器的传递函数,并利用Matlab分析软件中的Simulink模块对其分析与仿真,通过得到的动态特性仿真曲线,为提高换热器的使用效率提供一些依据。     

宏观过程的方向与限度——可逆性判据(Ⅱ)

本文从平衡判据的普遍规律--克劳修斯不等式出发,按照不同的过程条件,分别讨论了熵判据、亥氏函数和吉氏函数判据以及相变化和化学变化的可逆性判据.同时指出了这些平衡判据所包含的物理意义及它们间的一些内在联系.     

精细管理规范运作推进油田持续有效发展

介绍了江苏油田分公司推行全面预算管理,有效降低生产成本,规范会计基础工作,提升财务管理水平,实施精细成本管理,夯实油田有效、和谐发展的科学管理方法.     

甲基吡啶气相氨氧化V系催化剂研究进展

综述了国内外甲基吡啶气相氨氧化制氰基吡啶V系催化剂的研究进展。在甲基吡啶气相氨氧化中,V系催化剂可以以非负载和负载两种形式起作用。负载型V系催化剂因其机械强度、热稳定性和寿命更优异而得到更加广泛的应用和研究。     

组分对发射盐物相、浸渍温度和稳定性的研究

311、411、612、2.4：0．6：1是常用的阴极钪酸盐（Ba：Ca：Al2摩尔比，分别添加微量Sc2O3）配比。相同工艺条件，4种配比钪酸盐的衍射峰区别不大；相同温度条件，2．4：0．6：1的阴极钪酸盐对纯钨基的浸渍度最高，达到99．34％；同时24：0．6：1的阴极钪酸盐在空气中的稳定性也是最好的。     

BaTiO3系PTC热敏电阻用施主加入物的研究

阐述了常用的施主加入物、施主加入量、影响施主加入量的主要因素及各施主加入物的特点。研究了常用的施主加入物的理化指标对ＰＴＣ热敏电阻性能的影响，并据此提出了其技术标准。     

Finite-time consensus of multiple second-order dynamic agents without velocity measurements

This article considers the finite-time consensus of multiple second-order dynamic agents without velocity measurements. A feasible protocol under which each agent can only obtain the measurements of its position relative to its neighbours is proposed. By applying the graph theory, Lyapunov theory and the homogeneous domination method, some sufficient conditions for finite-time consensus of second-order multi-agent systems are established under the different kinds of communication topologies. Some examples are presented to illustrate the effectiveness of the theoretical results.