Homo‐oligomerization of maleic anhydride in nonpolar solvents: A kinetic study of deviations from nonlinear behavior

Deviation from nonlinear first order polymerization kinetic models is usually observed for cases where steric effects are dominant. A kinetic model was developed for the homo‐oligomerization of bulky maleic anhydride units. Factors affecting the kinetics of homo‐oligomerization of maleic anhydride have also been studied using two different initiators, azoisobutyronitrile (AIBN) and benzoyl peroxide, at 10 mol % concentrations in two different solvents o‐xylene and toluene. Maleic anhydride polymers having a number average molecular weight by SEC, between 300 and 900, and a polydispersity of between 1.0 and 2.0 were observed, and data were justified by the model. The molecular weight of the polymers increased with the conversion, and steric effects dominated at higher molecular weight as observed from the decrease in magnitude in the corresponding termination rate constants. The model values of conversion were compared with experimental data and cross verification of the model was done using molecular weight calculations. The present model represents the data with an average error of less than 5% over the entire experimental range. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3404–3412, 2006     

Characteristics of multistage column crystallizer for gas-liquid reactive crystallization of calcium carbonate

Crystallization of calcium carbonate using a gas (CO₂)-liquid (Ca(OH)₂) reaction was conducted using a three-stage column crystallizer. In this study, the staging effect of the multistage column crystallizer and the effect of the operating parameters on the particle size distribution were experimentally and theoretically investigated. From an economic viewpoint, the multistage column crystallizer has been developed to replace a cascade of MSMPR crystallizers, which requires a large installation area and high operating cost because some crystallizers are connected in a series. In the multistage column crystallizer, a narrower particle size distribution was obtained compared to that obtained in the standard column crystallizer. The theoretical approach to predict the particle size distribution is based on the population balance equation which takes account of the back flow into the crystallizer. The calculation results of particle size distribution fairly coincide with the experimental results, which indicates the particle size distribution in the multistage column crystallizer can be roughly predicted by this theoretical model.     

HS-SPME-GC-MS法测定纺织品游离甲醛

建立了纺织品游离甲醛的衍生．萃取．气质联用测定方法：试样剪碎后置于饱和NaCl溶液中，60℃超声波超声处理30min，用五氟苯盐酸氢胺衍生化后，采用顶空固相微萃取和色质联用技术（HS-SPME-GC-MS），选择离子（m/z181）进行定量。该方法适用于各类单层或多层纤维织物中甲醛的测定，加标回收率94．9％-98．7％，相对标准偏差2．97％-4．59％；方法检出限为0．02mg／kg。     

钢筋混凝土异形柱扭翘性能初探

通过重庆地区异形柱体系的产生和发展过程,阐述了异形柱在住宅工程中具有较好的使用价值及经济效益,分析了异形柱存在的扭翘缺陷并提出了使用异形柱的建议。     

脉冲筛板柱萃取分离钍鈾的研究(Ⅰ)——钍铀分离脉冲筛板柱的流体力学性能

在2英寸脉冲筛板柱中,结合钍铀分离的Thorex过程,研究了30％TBP-煤油/水和30％TBP-煤油/Th(NO_3)_4-UO_2(NO_3)_2-HNO_3-H_2O体系脉冲筛板柱的流体力学性能。通过实验对液泛通量、分散相存留分数等流体力学参数,并用改进的Pratt公式对两相流体力学流体力学行为进行了关联,得到了较为满意的结果。通过对脉冲筛板柱流体力学性能的研究,获得了最优操作条件,为进一步的传质实验研究奠定了基础。     

冲击载荷下复合材料层合杆的动力屈曲

研究复合材料层合杆被一质量块以某一速度沿轴向进行碰撞而导致的动力屈曲现象,采用不同的横向剪切理论,并用差分方法对杆的动力屈曲方程进行求解。文中考察了冲击块质量、初挠度、应力波、横向剪切等因素对临界冲击速度以及屈曲模态的影响。     

填料型饱和热水塔数学模拟

本文对填料型饱和热水塔最佳工况模拟,对该类型塔的计算机数学模拟进行了讨论。     

HPLC无孔径载体柱用于快速分离蛋白质和多肽

介绍了一种新型的高效液相色谱柱的结构特点及其在蛋白质、多肽及遗传工程产品分析中的应用。在相同的洗脱条件下，与常规柱相比，无孔径载体柱高效、快速，特别是它能分离分子量较大和疏水性较强的蛋白质。此外，就无孔径载体柱在使用过程中对仪器的要求作了阐述，还讨论了温度对柱效的影响以及灵敏度与梯度时间的关系等。     

RE-Carbide in High Carbon Steel

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