PBT非等温结晶动力学

用差示扫描量热法研究聚对苯二甲酸丁二酯（PBT）的非等温结晶动力学，并分别用Ozawa,Jeziorny和考虑综合因素法来处理PBT的非等温结晶数据。结果表明，PBT非等温结晶过程与Ozawa动力学方程相吻合，但不符合用Jeziorny方法处理的Avrami动力学方程；综合考虑温度和结晶程度对聚合物结晶速度的影响。PBT非等温结晶过程符合结晶动力学方程。     

在役涡轮搅拌桨混合过程流热耦合有限元分析

化工搅拌装置内的流体流动伴随着显著的传热过程,由于搅拌流动的复杂性以及温度的分布难以测量,采用试验法具有一定的局限性。利用计算流体力学(CFD)软件,采用标准k-ξ紊流模型,分析了非稳态非等温情况下,涡轮搅拌桨混合过程中搅拌槽中流体的三维紊流流场和温度场的分布。结果表明,大型搅拌反应装置采用搅拌桨通蒸汽加热方式,能够使搅拌槽温度分布更加均匀,热量扩散更加迅速。     

粘弹性流体非等温本构方程

本文将Giesekus提出的单模式平均构型分子模型推广到非等温情形,然后利用人们熟知的粘温关系式来计及温度和热历史对应力张量的影响,得到一个描述聚合物浓溶液和熔体非等温流变性质的本构方程,不必在分子模型中引入人为的假定来考虑非等温效应.对于非等温应力发展的计算表明,这一本构方程能避免以前研究者提出的本构方程的缺点,合理地描述聚台物流体的非等温流变性质.     

PA 6非等温结晶动力学研究

用差示扫描量热法研究了聚酰胺(PA)6的非等温结晶动力学,并分别用Ozawa法、Jeziorny法和莫志深方程法处理PA 6的非等温结晶行为。结果表明:Ozawa法和Jeziorny法均不能很好地描述PA 6非等温结晶过程;莫志深方程结合Avrami和Ozawa方程,可很好地描述PA 6非等温结晶过程;PA 6的结晶受温度的影响较大,一旦成核,结晶可在短时间内发展得比较完善。     

管道防腐用高密度聚乙烯的非等温结晶行为

采用差示扫描量热法考察了管道防腐专用高密度聚乙烯(SHDPE)专用料的非等温结晶行为,并结合Ozawa、莫志深等方程对非等温结晶动力学过程进行研究,并与专用料的基础树脂(BHDPE)进行了对比.结果表明:随着降温速率增加,SHDPE,BHDPE的结晶起始温度和结晶峰温度均向低温方向移动,且达到相同相对结晶度的时间减少,SHDPE的结晶能力低于BHDPE,但SHDPE的晶体完善程度高于BHDPE;Ozawa方程不适于描述冷却速率较低时(5℃/min)的SHDPE,BHDPE的非等温结晶过程,而莫志深方程能很好地描述该过程.     

聚苯硫醚/多壁碳纳米管复合材料非等温结晶研究

采用DSC法研究了聚苯硫醚(PPS)及多壁碳纳米管(MWCNT)复合材料的非等温结晶过程,采用莫志深方程分析了复合材料的非等温结晶动力学特性。结果表明,莫志深方程能够较好地描述PPS/MWCNT复合材料的非等温结晶动力学,MWCNT的加入促进了PPS结晶,材料的结晶温度、结晶速率都明显上升。复合材料的结晶温度和结晶速率随MWCNT用量的增加呈先上升后下降的变化趋势,当MWCNT质量分数为3%时两者都达到最大。     

碳纳米管/尼龙6复合材料的非等温结晶动力学研究

碳纳米管经过了酸化处理,用FTIR对处理后的碳纳米管进行了结构表征.采用哈克转矩流变仪制备了碳纳米管/尼龙6纳米复合材料.利用SEM对碳纳米管与尼龙6复合材料的结构进行了研究.通过DSC对复合材料的非等温结晶动力学进行了研究,采用Jeziorny修正的Avrami方程对非等温结晶动力学进行了处理.结果表明,Jeziorny 可以很好地描述碳纳米管/尼龙6复合材料的非等温结晶过程.随着降温速率的升高,结晶温度降低,结晶温度范围变大,结晶所需要的时间缩短.     

PBT聚酯非等温结晶动力学

用差示扫描量热分析(DSC)法研究聚对苯二甲酸丁二酯(PBT)的非等温结晶动力学,并分别用Ozawa、Jeziorny和综合因素法等三种方法来处理PBT的非等温结晶数据。结果表明,PBT非等温结晶过程与Ozawa动力学方程相吻合,而不符合用Jeziorny方法处理的Avrami动力学方程;综合考虑温度和结晶程度对聚合物结晶速度的影响,PBT非等温结晶过程符合结晶动力学方程:dG(t)/dt=e~(-E/R(T-T_R)+F(T_m-T+α))(1-G(t))~nG(t)~m。     

L形异型材共挤胀大及变形的三维非等温数值模拟

采用PTT本构方程,应用Arrhenius方程来描述温度对黏度的影响,建立了L形双层共挤模型,通过有限元方法分析了聚丙烯（PP）和聚苯乙烯（PS）熔体的三维非等温黏弹流动过程,对比分析了2种材料在不同组合情况下口模出口面的速度场、剪切速率场以及共挤出胀大和变形情况。结果表明,L形分层共挤的胀大和变形不仅与2种熔体黏度差异有关,还与口模截面形状有关;黏度较低的PP会向黏度较高的PS一侧偏转,且PP有包覆PS的趋势;黏度较低的PP位于L形内侧时共挤出胀大和变形程度大于其位于外侧时,且两熔体黏度差异越大,两方案的共挤出胀大和变形程度的差异越大。     

非啮合双螺杆挤出过程常规螺纹元件流道三维流场分析——等温牛顿模型

利用ＡＮＳＹＳ有限元分析软件对非啮合双螺杆挤出机螺纹元件中的牛顿流体等温流动进行了三维模拟分析。在得出速度场和压力场的基础上,分析了不同几何条件及操作条件对输送特性及混合能力的影响。     

锚式搅拌槽中高粘弹性流体的流速分布及其功率消耗

用照相法测定了锚式搅拌槽中高粘弹性流体的流型和流速分布,另测定了搅拌功率消耗,结果发现:1.与牛顿流体相比,在低Re数下,粘弹性流体的切向速度较大,而径向速度则较小.2.转速相同时,在高剪切率区域,粘弹性流体的剪切率大于牛顿流体.由CEF方程导出功率计算式N_pRe_af_s~(1-n)=k_pf_vf_s~2[1+F_1avf_s~(m-n-3)Wi/K_s~2]用实验数据确定f_(?)和F_(1av),得到可适用于牛顿流体、假塑性流体和粘弹性流体的普适功率计算式,计算结果与实验值比较接近.     

An effect of the impeller eccentricity on the process characteristics in an agitated vessel—experimental and numerical modeling

An effect of the impeller eccentricity on the process characteristics in an agitated vessel was analyzed on the basis of our own experimental and numerical results obtained within the turbulent range of the Newtonian liquid flow. Mixing time, power consumption, local and mean values of the heat transfer coefficients and distributions of the transport coefficients (shear rate and friction coefficient) at the vicinity of the vessel wall were studied experimentally within the wide range of the operating and geometrical parameters of the agitated vessel equipped with eccentrically located high-speed impeller. Numerical simulations of hydrodynamics in an agitated vessel with eccentrically located axial flow impeller (up-pumping propeller or downpumping HE-3 impeller) were carried out using CFD method.     

搅拌槽中高粘度液体温度分布均匀性研究

本文提出用无因次量描述搅拌槽中高粘度液体温度场的不均匀性.对螺带桨搅拌液体作层流时的无因次微分方程进行分析得到(?)=f(Pe、Ec/Re).用实测的牛顿流体及假塑性流体槽液温度回归获得螺带-锚及螺带-螺旋轴-锚等五种组合桨(?)的关联式.内外螺带-锚(Ⅰ)桨是五种桨中最优良的桨型.     

On helical flows of polymer fluids

Isothermal and non‐isothermal steady helical flows are theoretically investigated under the assumption that the flow is fully developed in both the thermal and hydrodynamic senses. It is well known that the basic gross characteristics of steady isothermal helical flows of non‐Newtonian liquids can be found relatively easily if the flow curve (or non‐Newtonian viscosity) in simple shearing is known. Nevertheless, evaluation of more detailed viscoelastic properties in this type of flow is also sometimes desirable. These properties are shown to be exactly determined in both the isothermal and non‐isothermal cases as soon as a nonlinear viscoelatic constitutive equation is specified. Shear thinning due to fluid rotation and strong temperature dependence of Newtonian viscosity highly increase dissipative heat. This can produce significant non‐isothermal effects in intense helical flows, even when the wall temperature is kept uniform and constant. It is shown that the energy consumption in isothermal and non‐isothermal helical flows is always higher than in respective annular flows with the same flow rate. Comparisons between our calculations and available experimental data are also discussed.     

连续混炼机转子端面几何形状的理论研究

建立新型连续混炼机的转子三维非牛顿等温流场模型，利用ANSYS软件和自编程序，对转子流场中的周向回流量及平均剪切应力进行了模拟计算，讨论了端面几何形状变化对周向回流量及平均剪切应力的影响。     

A new expression of the Ks factor for helical ribbon agitators

The purpose of this note is to present a new model that is able to predict an effective shear rate in a vessel equipped with helical ribbon agitators, when mixing shear‐thinning fluids. This model is based on well established results obtained for non‐Newtonian flow in cylindrical ducts.     

啮合同向双螺杆挤出过程轴向循环流道三维流场分析—轴向循环流场分析（Ⅱ）

介绍了作者在啮合同向双螺杆某一轴向位置设置一非啮合段（且该段其中一根螺杆是反向螺纹元件）,从而将轴向循环流动的概念引入到啮合同向双螺杆挤出过程中,并利用ANSYS有限元分析软件对啮合同向双螺杆挤出过程轴向循环流道中的非牛顿流体等温流动进行了三维模拟分析。在得出速度场和压力场的基础上,还对剪切速率、剪切应力及剪切粘度进行了模拟,并将各模拟结果与未引入轴向循环流的啮合同双螺杆挤出过程常规螺纹元件流道的模拟结果进行了比较。     

最大叶片式桨在假塑性流体中的搅拌流场模拟

为研究最大叶片式桨在高黏假塑性流体中的搅拌流动行为,以黄原胶溶液为研究体系,采用计算流体力学方法重点研究了釜内流体的功耗特性、速率分布、剪切速率、表观黏度分布和总体流动状况。结果表明:最大叶片式桨具有与大多数径流桨相似的"双循环"流型结构,且预测的功耗特性与实验数据一致性良好。最大叶片式桨适用于高黏假塑性流体的混合,而对于高黏牛顿流体的混合则效果不佳。釜内的剪切速率分布较宽泛,且受转速影响较大。转速可作为该桨改善黄原胶体系混合效率的重要参数之一。     

Numerical analysis of a reactive extrusion process. Part II: Simulations and verifications for the twin screw extrusion

A newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self‐wiping co‐rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di‐t‐butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network (FAN) method with non‐isothermal non‐Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.     

非牛顿流体和牛顿流体在搅拌槽内的传热研究

本文根据边界层理论,通过搅拌槽壁面扭矩与搅拌桨旋转扭矩近似相等的关系,提出非牛顿流体在搅拌槽传热阻力层的实际表观粘度的计算方法.使佐野雄二的给热系数关联式也能适用于不同桨型的非牛顿流体的给热系数计算,从而获得了同时适用于牛顿流体和非牛顿流体在装有各种桨型的搅拌槽壁侧给热系数的统一关联式: