Optimization of the Arrangement of Mixing Sheets in VK Tube

The flow mechanism of Nylon-6 melt over perforatedbaffles with conical shape in the VK tube is explained bycomputerized analysis based on a rational assumption ofStokes’flow.The governing equations for a two-dimen-sional flow are solved by finite difference method to gen-erate the stream function profile,velocity field and resi-dence time distribution.Optimization of the geometriesof the baffle structure brings about a uniform residencetime distribution of the melt,so as to ensure a homoge-neous extent of reaction for the final product.Furthertheoretical investigation shows that dead zones areformed and that a rule of thumb has to be practiced fortheir elimination.     

Polyamide-6 Polymerization in the VK Tube Reactor with Baffle Structure

The melt flow mechanism of polyamide-6 (PA6) was simulated with the mathematical flow model and tested by Particle Image Velotrimitry (PIV) . The complete mathematical model for PA6 polymerization while flowing through the VK tube reactor was established according to PA6 hydrolytic polymerization kinetics. The characteristic data such as residence time, caprolactam conversion and the degree of polymerization (D. P.), at every stage of polymerization reaction and at every point of the VK tube were presented for the melt flowing through ten alternate conical baffles in VK tube.     

二元物系间歇精馏的操作和优化

间歇精馏在数学描写上是一个非稳态过程。这是它和连续精馏(稳态过程)的一个基本不同点.要从理论上对它进行完整的分析,必须把逐板计算法和物料衡算、焓衡算的微分方程结合起来。本文针对 NMP-水系统的间歇精馏实践,阐明了这种计算机处理方法的优点和必要性。在一定的约束条件下,采用恒摩尔假定的逐板关系,建立间歇精馏过程的基本微分方程及算法。它不仅解释了实验现象,提出了设计方案,还在动态分析的基础上求出最优化操作过程。     

挤出流动的力学行为 第一报;双组分流体的出口弯角与茶壶效应

本文从流体力学的基本定律出发,从理论上分析了流体在狭缝出口处的力学行为.研究表明,流体在出口横截面上的剪切应力是导致流体弯曲的根本原因;探讨了出口弯角的方向;导出了出口弯角的计算公式.实验采用流变性能不同的两种流体从狭缝模并列挤出,测定了弯角的大小和方向.实验结果与理论分析相一致.     

PA6/69熔融共混体系酰胺交换反应动力学模型——Monte Carlo模拟

建立了酰胺交换反应动力学 Monte Carlo的基本模型,并用该模型对 PA6/69熔融共混体系中4种酰胺键摩尔分数随时间的变化进行了模拟.模拟结果表明,PA6/69嵌段共聚物在283℃下的寿命为8h,这与Nllen的研究结果相吻合.     

液—液萃取—分散相滴径的分布及简化的传质模型

当往复式叶片萃取塔正常操作时,逆流通过塔内的轻重二相受到叶片搅动,出现分散相液滴脉动翻飞十分剧烈的景象,因此提高了传质效果。本文报导了对这些液滴大小分布的研究,同时还对苯—丙酮—水以及甲苯—丙酮—水两个系统在塔内的传质机理作了初步的理论分析,除测算了有效传质介面F_Σ,并笼统地求出K_x外,另用扩散方程模拟了传质过程,能说明一些“双膜理论”所无法估计到的问题。     

挤出流动的力学行为——第二报:牛顿流体的模口膨化

作者继第一报证明了模口处的横向剪切应力是产生出口弯角的根源之后,进一步对牛顿流体的模口膨化效应进行了研究。从理论上证明了模口处的横向剪切应力也是影响牛顿流体模口膨化比的重要因素。另外三个影响牛顿流体模口膨化比的力是:流体流出狭缝后外层流体对内层流体作用的粘性拖曳力,流体的惯性力和表面张力。推导出这4种力与模口膨化比的定量关系式,由这一关系式可明显看出粘性、惯性和表面张力是如何影响模口膨化的,从而解释了许多别人的实验结果和数值计算结果。     

PA6 Obtained by Polymerization with Trifunctional Regulators and Its DSC Results

Hydrolytic polymerization of 8 - caprolactam is carried out by the use of trimesinic acid as molecular weight controlling agent, and polyamide 6 with three branched chains is obtained. The initial concentrations of regulators almost have no effect on the conversion of caprolactam , while relative viscosity of the polymer is affected by the concentrations. DSC investigation shows that DSC curve changes from single peak for regular polyamide 6 to one peak with one shoulder or one small peak for polyamide 6 with three branched chains and the melting point decreases with the increase of the amount of trimesinic acid. In addition, the concentration of trimesinic acid being the same, DSC curves change from almost sharp single peak to double peak with increasing reaction time.     

聚乳酸的固相聚合研究

对聚乳酸的新聚合方法-固相聚合进行了研究,探讨了聚合温度、聚合时间、氦气流量、催化剂等对聚乳酸粘均相对分子质量的影响;验证了固相聚合方法的有效性。     

A THEORY ON TEA-POT EFFECT

In this paper exit.bend angle(tea-pot effect)has been analysed theoretically based on thebasic)aw of hydromechanics.It was proved that it is the transverse shear stress that causes exitbend angle while the bending direction is along with the resultant force of the shear stresses andthe magnitude of the exit angle is directly proportional to the resultant force.The equation re·lating exit bend angle with the resultant force was set up and experiment verification of theequation was carried out with rational agreement to theoretical results.