端羟基聚丁二烯固化热效应的影响因素研究

通过对黏合剂端羟基聚丁二烯(HTPB)固化时温度变化的测定,探讨了影响HTPB固化热效应的因素。采用单因素实验研究了不同实验条件下固化参数、固化温度、催化剂对HTPB固化热效应的影响。结果表明,在固化温度为60℃时,固化参数R越大,固化放热量越大,固化反应速度越快;在其他工艺参数相同的情况下,固化温度越高,HTPB及TDI的反应活性越高,放热越快,持续时间也越长。在黏合剂HTPB体系中加入二月桂酸二丁基锡(T-12)催化剂可大大提高固化反应速率,缩短固化周期,降低反应活化能。     

轮胎花纹噪声动力学分析

从动力学角度研究轮胎花纹噪声的发声机理。分析得出，车速越快、轮胎充气量越小、花纹块的密度越大，花纹块的噪声声压越大；花纹槽的腔体积、车速和汽车载质量越大，花纹槽的噪声声压越大。从噪声波干涉与合成的角度论述花纹结构参数对轮胎花纹噪声的影响。     

共价键型絮凝剂去除有机磷的定量构效关系

选用新型絮凝剂CBHyC对7种有机磷模拟废水进行絮凝处理,并对其去除率与有机磷结构参数进行相关性分析。发现CBHyC对有机磷的去除率与分子轨道最高占有能(E_(LUMO))、分子结构总能量(TE)、磷原子电荷(Q_P)、结构体系内氢原子电荷最大值(Q_H~+)和碳原子电荷最大值(Q_C~-)这5个有机磷分子结构参数的相关性显著。Q_p和Q_H~+的数值越大,或者Q_C~-的数值越小,CBHyC对有机磷的去除率越高;E_(LUMO)越大,有机磷得电子能力越强,去除率越高;TE越大,有机磷越难以反应,去除率越低。该研究结果可为絮凝去除率与有机磷结构的定量构效关系(QSAR)模型的构建、絮凝条件的优化和结果预测等方面提供有效的数据支撑。     

SiCp/Al复合材料界面反应的XRD及热力学分析

利用XRD分析了影响SiCp/Al系统界面反应的因素,得出以下结论:铝合金中Si,Mg元素越多界面反应越小;温度越高时间越长,界面反应越大.进一步从热力学的角度对界面反应进行了计算和分析,得到用XRD相同的结果.     

纺黏非织造布工艺参数对纤维直径的影响

对有关纺黏工艺参数对纤维直径的影响进行了仿真实验和讨论,对不同的工艺参数进行了数值模拟,并对聚合物细流的最终直径进行了实测,发现聚合物挤出量越小,聚合物熔体温度越大,气流初始温度越高,气流初始速度越大时,越有利于聚合物熔体的气流牵伸,纤维直径越小;实验结果显示:测试结果与模型预测值十分吻合。本研究也显示了在对纺黏非织造布工艺和设备进行计算机辅助设计方面具有较好的应用前景     

比表面积

比表面积是衡量粉体材料粒子粗细(或粒径大小)的指标，用m^2／g表示。材料的粒径越小，则比表面积越大。粉体粒子的粗细不仅影响加工难易程度(粒子越细，分散越难)，且对橡胶的力学性能也有决定性的作用。比表面积越大，补强效果越好，这就意味着橡胶与粒子间接触和反应的机会越多。以炭黑为例，比表面积与粒径之间存在着对应关系，如下表所示。     

LAS生物降解性与分子结构的定量相关研究

用量子化学方法计算得到了LAS的分子结构参数，应用这些分子结构参数对LAS生物降解的实验结果进行回归分析，建立了以分子总电子能(Ee)、分子偶极距(μ)、前线轨道电子云密度指数(Fr^N)为结构描述符的降解率D％的数学模型。表明：①烷基碳原子数相等而苯环位置离中心碳原子越近，Ee值越负、Fr^N越大、偶极矩μ越小其生物降解性越低；②苯环离末端碳原子位置不变即碳原子数减少的LAS分子，Ee值越正、Fr^N越大、偶极矩户越小其生物降解性越低。可见μ与Fr^N在各种结构系列中均适用，是与生物降解活性相关的主要结构描述符。     

固定床催化反应器中平行反应的飞温现象Ⅱ冷却介质温度沿反应器轴向变化

对冷却介质温度沿反应器轴向变化时平行反应的飞温现象进行了研究,揭示出临界等浓度曲线拐点是冷却介质温度沿轴向变化时反应系统发生飞温的临界点。研究结果表明冷却介质对反应系统飞温区域的影响和反应物料与冷却介质的热容量之比α有关,α越大反应系统的飞温区域越大,得到的飞温区域上下限之间的差异也越明显。     

以固载氯烷基硅氧烷的硅烷的硅胶中间体为原料制备水不溶性杀菌剂

考察了以固载了γ－氯丙基三甲氧基硅氧烷的硅胶中间体为原料制备不溶性杀菌剂的最佳条件：在二氧六环溶中，在室温下反应48h以上。使用十二叔胺、十四叔胺、十六叔胺在最佳反应条件下都可制成对异养菌杀菌率在90％以上的产品。原料的比表面积越大、孔体积越小、平均孔径越小，合成产品的杀菌活性越高。对于相同型号、不同粒度的硅胶原料，粒度越小杀菌活性越高。     

新拌水泥浆体絮凝结构与流变行为及有效体积分数的关系(英文)

在不同水灰比条件下对两种超塑化剂新拌水泥浆体絮凝结构的易变形性、破坏程度、平均大小、解絮及再絮特性与流变行为和有效体积分数的关系进行了研究,通过测定和计算浆体流变参数、触变性(触变环面积)及有效体积分数,表征了浆体絮凝结构的特性。结果表明:浆体流变参数屈服应力τ0反映浆体的变性能力,τ0越小絮凝结构越易变形;浆体触变环面积As越大,絮凝结构的破坏程度越大;浆体的剪切稀化、剪切稠化行为可表征解絮与再絮程度;有效体积分数越大,絮凝结构平均尺寸越大。     

A PRIORI ESTIMATION OF CHEMICAL RELAXATION OSCILLATIONS VIA A SINGULAR PERTURBATION TECHNIQUE

The application of a zeroth order singular perturbation technique to certain models of chemically reacting systems exhibiting relaxation oscillation behavior is presented. Resultant estimates of amplitudes and periods for two well-studied systems—viz., CO oxidation on platinum and the nth order reaction in the CSTR—are shown to be in good agreement with values determined by numerical integration of the respective model equations. Also presented is a method by which regions in parameter space where limit cycles exist may be determined a priori. This method, coupled with accurate experimental data, could prove to be a powerful tool in the critical evaluation of and discrimination between candidate models of chemical oscillations.     

A PRIORI ESTIMATION OF CHEMICAL RELAXATION OSCILLATIONS VIA A SINGULAR PERTURBATION TECHNIQUE

The application of a zeroth order singular perturbation technique to certain models of chemically reacting systems exhibiting relaxation oscillation behavior is presented. Resultant estimates of amplitudes and periods for two well-studied systems—viz., CO oxidation on platinum and the nth order reaction in the CSTR—are shown to be in good agreement with values determined by numerical integration of the respective model equations. Also presented is a method by which regions in parameter space where limit cycles exist may be determined a priori. This method, coupled with accurate experimental data, could prove to be a powerful tool in the critical evaluation of and discrimination between candidate models of chemical oscillations.     

半连续脂肪酸甲酯化过程的研究(Ⅱ)——操作优化

对半连续脂肪酸甲酯化的操作优化问题进行了研究.定义生产费用为操作优化的目标泛函,选择甲醇进料速率为控制变量、反应压力为控制参数,分别应用动态规划法和Powell法对上述操作优化问题求解.两种方法求解的结果是一致的,采用优化的操作将使生产费用降低5%～15%,特别对有催化的快速甲酯化过程,优化操作的效果更明显.文中还讨论了价格等因素对优化操作策略的影响和求解计算量问题.实验表明,由理论计算得到的优化操作策略和目标是可以实现的.     

半连续脂肪酸甲酯化过程的研究(Ⅱ)——操作优化

对半连续脂肪酸甲酯化的操作优化问题进行了研究.定义生产费用为操作优化的目标泛函,选择甲醇进料速率为控制变量、反应压力为控制参数,分别应用动态规划法和Powell法对上述操作优化问题求解.两种方法求解的结果是一致的,采用优化的操作将使生产费用降低5%～15%,特别对有催化的快速甲酯化过程,优化操作的效果更明显.文中还讨论了价格等因素对优化操作策略的影响和求解计算量问题.实验表明,由理论计算得到的优化操作策略和目标是可以实现的.     

Modelling of chemical reactors-XXXII: Nonisothermal Nonadiabatic Tubular Reactor. One Dimensional Model-detailed Analysis

A detailed analysis of the region of multiple steady states in nonisothermal-nonadiabatic systems is performed. It is shown that in a certain region of Damköhler numbers five steady states are possible. These steady states are referred to as the kinetic, diffusion and intermediate regimes. Numerical procedures for calculation of regions of multiplicity are described. Numerical analysis of the problem indicates that with higher value of the cooling parameter β multiplicity is suppressed. For higher values of the Peclet number multiple steady states disappear. The analysis has shown that in nonadiabatic systems Frank-Kameneckij approximation of the temperature dependence of the reaction rate must be used with some care.     

Steady‐state multiplicity in an adiabatic continuous stirred tank reactor with vapor recycle

The multiplicity features of a continuous stirred tank reactor with vapor recycle have been studied for a dimerization reaction with second‐order kinetics. Such reaction systems are common in the polymer industry. The aim of the analysis is to provide a simple design methodology that will ensure safe operation of the reactor. It is shown that solutions with and without vapor recycle exist. The bifurcation set for the system is calculated, and 11 different bifurcation diagrams arise. A linear relationship exists between the system parameter values, when these are normalized by their values at the ignition point. This leads to a simple method for defining a safe operating point for the system under a defined disturbance. © 2012 American Institute of Chemical Engineers AIChE J, 59: 553–559, 2013     

间歇放热反应系统热失控参数敏感性研究

以参数敏感性定义作为理论基础和数学依据,证明了一级间歇放热反应系统操作曲线与温度最大点曲线的拐点轨迹相切的点是反应系统热失控的参数敏感点,从理论上给出了反应系统的安全操作所允许的温度上限。利用敏感点和超临界操作曲线的拐点关系,推导出反应系统安全操作的临界判据。将该临界判据与Adler和Enig、van Welsenaere和Froment以及Wu等的经典判据进行比较,结果与文献值基本一致。将该临界判据和经典判据与Allen和Rice的实验结果进行对比,该标准也能很好地预测出偶氮甲烷分解爆炸的压力。     

Thermal regimes of exothermic processes in continuous stirred tank reactors

Thermal regimes of a CSTR are analysed from the standpoint of the thermal explosion theory. Critical phenomena and time characteristics of the process are considered. It is shown that for appropriately chosen dimensionless parameters the critical conditions of the thermal explosion and induction period in a CSTR slightly differ from those for non-flow (batch) systems. These corrections may be performed by using an additional parameter which is characteristic for flow systems. In the region of multiplicity of steady states, the critical condition of thermal explosion is characterized by a jump of self-heating, while in the non-flow systems such phenomenon occurs only for a zero order reaction. For a unique steady state the transition through the critical condition is continuous.     

A perturbation method for spherical and cylindrical solidification

A new method is used to find the perturbation solutions of inward and outward solidification of a saturated liquid in spherical as well as cylindrical containers. The method consists of (1) immobilizing the moving boundary by Landau's transformation, (2) using the normalized position of the moving interface to replace the time variable, and (3) applying regular parameter perturbation techniques. The quasi-steady state solutions are the zero-order solutions for the four cases. No singular point is found for outward solidification. Singular point exists at the end of inward solidification for spherical and cylindrical system for the perturbation solutions of temperature distribution being equal to or higher than the first order solutions, and freezing time solution of interface position being equal to or higher than the second order solutions.     

一类拟线性奇异摄动问题的指数型差分格式

讨论了求解一类拟线性奇异摄动问题的指数拟合型差分格式。证明了差分格式的解在动范数意义下关于摄动参数的一致一阶收敛性。