橡胶增塑剂A1220的运动粘度-温度特性研究

研究橡胶增塑剂A1220运动粘度-温度特性,推算橡胶增塑剂A1220在不同温度下的运动粘度。用运动粘度测试值通过拟合和经验式计算,得到拟合运动粘度-温度方程和经验式运动粘度-温度方程,并将计算值与测试值进行对比。结果表明:橡胶增塑剂A1220在100～160℃内的拟合方程计算的运动粘度准确度较高,在180～200℃内的经验式方程计算的运动粘度准确度较高。     

液体混合物的粘度方程

本文基于Eyring纯液体粘度理论,并引进局部克分子组成概念,提出一个液体混合物粘度方程 其中 A_(ij)=exp〔-(g_(ij)-g_(ii))/RT〕 该方程被应用于近30个二元体系和5个三元体系的计算,结果表明,它对于二元实测粘度数据的关联和多元粘度～组成关系的预测都是相当有效的。 文中对方程的建立、参数的物理意义和方程的适用性进行了探讨。     

注射成型过程中非牛顿塑料熔体的粘度模型

本文在探讨塑料熔体粘度模型基础上,重点讨论了一种适用范围更广的Cross粘度模型,并根据塑料熔体在注射成型过程的流动特点,采用Arrhenius方程建立了适用于注射充填过程的五参数Cross粘度模型和利用WLF方程建立起适用于注射保压过程的七参数Cross粘度模型。具体讨论模型的特征和适用范围,为注射模设计和成型模拟提供了理论依据。     

从液体混合物的粘度数据推算汽液平衡数据

<正>液体混合物的汽液平衡数据和粘度数据都是基本的物性数据,人们很早就开始了对它们的研究,并取得了不小的进展.对于汽液平衡的研究,人们提出了许多溶液理论和活度系数方程,例如Flory-Huggins方程,Van Laar方程,Margules方程,Wilson方程和其修正方程,NRTL方程以及UNIQUAC方程等;对于液体混合物的粘度,人们也提出了许多流体粘度理论,其中最著名的是Eyring反应速率理论.作者曾应用这一理论建立了一个新的液体混合物粘度方程,用于关联二元体系的粘度数据和推算多元体系的粘度数据,结果令人满意.     

超声波改善稠油流变性的实验研究

主要进行了超声波对稠油流变性影响的实验研究,通过均匀设计来安排实验,进行了超声波功率、超声波作用时间和间隔比3个因素与超声波处理后稠油粘度之间关系的实验,并拟合出这3个因素与稠油粘度的经验方程,进一步分析了超声波对稠油流变性影响的规律。     

淀粉-聚丙烯酰胺接枝共聚物分子量的测定——对Mark-Houwink经验方程式的探讨

用稀溶液粘度法测定淀粉接枝共聚物分子量,通常是先将共聚物中淀粉水解,再用粘度法测出接枝支链部分的平均分子量后求得。本文以淀粉-聚丙烯酰胺接枝共聚物为例,论证在一定N_9情况下,有相应的MarkHouwinlk经验方程,由此可直接通过相应的经验方程计算淀粉接枝共聚物的分子量。     

由虚拟粘度概念求无限稀释液相扩散系数

依据理论模型推导出由虚拟粘度概念估算无限稀释液相扩散系数的关系式.虚拟粘度可由混合物粘度确定,也可从纯物质的粘度估算.仅由纯物质粘度计算虚拟粘度,本文方程对50个扩散系数的估算误差为10.6%,而Wilke—Chang方程和Tyn-Calus方程的估算误差分别为22.9%和14.2%.     

AFG-90环氧树脂/氰酸酯树脂共聚物流变特性研究

通过动态粘度和等温粘度测试研究了AFG-90环氧树脂/氰酸酯共聚物体系的流变特性,根据双阿累尼乌斯方程建立了环氧树脂/氰酸酯共聚物的化学流变模型,并对共聚物的粘度和工艺条件进行了预测。结果表明:60～160℃时共聚物体系的相对粘度特性符合双阿累尼乌斯粘度方程;低于60℃时体系共聚反应迟缓,初始粘度较高;随着温度升高,树脂初始粘度下降,在170℃附近粘度急剧上升,粘度随时间延长增加,理想的加压时机是温度升至125℃后保温30min。     

炭黑／聚醚多元醇体系流变研究

研究了炭黑 /聚醚多元醇体系流变性能。包括原料体系粘度的非牛顿性和不同品种炭黑对粘度的影响。通过扫描电镜研究了炭黑的形态和平均粒径 ,定性讨论了炭黑微观形态与流变性能的关系 ,给出了炭黑含量对粘度影响的经验方程     

粘土/水分散体系的粘度方程

测定了不同分散相浓度及不同剪切速率条件下蒙脱石粘土 /水分散体系的表观粘度 ,采用将分散相浓度外推到零的方法求得分散体系的极限粘度 ,建立了体系极限粘度与分散相浓度之间关系 ,讨论了影响粘度方程的因素     

EFFECT OF VISCOSITY ON HYDRODYNAMIC PROPERTIES OF PULSING FLOW IN TRICKLE BEDS

New data on pulsing flow onset, properties of pulses (frequency, celerity, length), liquid holdup and pressure drop are presented for aqueous glycerol solutions of viscosity 6.7 and 20.2 mPa s and compared with similar measurements from an air-water (1.0 mPas) system. With the exception of viscosity, all other physical properties of the liquid phase are kept constant and fairly close to those of water, thus allowing a direct assessment of the effect of viscosity. Pulse formation and propagation with viscous liquids is examined on the basis of time records from a conductance type technique. A striking effect due to increased liquid viscosity is the reduction of the pulsing flow regime; in particular, the pulsing-to-bubbling transition boundary is shifted towards higher gas flow rates. Pulse frequency and celerity appear to decrease only slightly with increasing liquid viscosity, whereas the two-phase pressure gradient increases significantly. Liquid holdup also tends to increase with viscosity. Moreover, holdup with viscous liquids tends to increase significantly with the liquid flow rate, whereas an insignificant effect is found for water. A new correlation for estimating liquid holdup is proposed, and a simple model for predicting pulsing flow characteristics is modified in order to take account of the aforementioned effects.     

Effect of viscosity on liquid curtain stability

The effect of viscosity on liquid curtain stability was explored by high‐speed visualization. Measurements of the velocity within the curtain revealed the presence of a viscous boundary layer along the edge guides. The critical condition at the onset of curtain breakup was determined by identifying the flow rate below which the curtain broke for two different edge guide geometries: parallel and convergent. Curtain breakup was initiated by the expansion of a hole within the curtain. For low viscosity liquid, the measured hole retraction speed is independent of the viscosity and equal to the Taylor‐Culick speed. For high viscosity liquids, the retraction speed is lower than the Taylor‐Culick speed due to viscous forces that resist the flow. The results also show the effect of liquid viscosity on the curtain stability is a strong function of the edge guide design. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1448–1457, 2018     

旋转填充床内高黏介质脱除有机挥发组分过程强化

The removal of a volatile organic compound (VOC) from high viscous liquid was carried out in a rotating packed bed (RPB) in this study. The mixed liquid of syrup and acetone was used as simulated high viscous polymer solution with acetone as the volatile compound. The influence of the rotating speed of RPB, liquid viscosity, liquid flow rate, vacuum degree, and initial acetone content in the liquid on acetone removal efficiency was investigated. The experimental results indicated that the removal efficiency increased with increasing rotating speed and initial acetone content in the viscous liquid and decreased with increasing liquid viscosity and flow rate. It was also observed that acetone removal efficiency increased with an increasing vacuum degree and reached 58% at a vacuum degree of 0.1 MPa. By the comparison with a flash tank devolatilizer, it was found that acetone removal ef-ficiency in RPB increased by about 67%.     

Computational study of planar extrudate swell flows with a viscous liquid–gas interface

We present a computational study of planar extrudate swell flows of Newtonian liquids with a viscous liquid–gas interface. The model consists of the equations of motion coupled with the Boussinesq–Scriven constitutive equation for the interfacial stress tensor. The resulting set of equations is solved with the finite element method coupled with an elliptic mesh generation strategy to capture the free surface. The results show a detailed parametric study in terms of the capillary number and the Boussinesq number, a dimensionless parameter used to measure the ratio of viscous forces at the interface to viscous forces in the bulk liquid. The predictions reveal that the extrudate swells dramatically as the interfacial viscosity grows. The interfacial viscosity slows down the flow both in the bulk liquid and at the interface, and thus the extrudate size increases to conserve mass in the slow plug flow that develops under the free surface.     

Prediction of the plastic viscosity of self-compacting steel fibre reinforced concrete

Micromechanical constitutive models are used to predict the plastic viscosity of self-compacting steel fibre reinforced concrete (SCFRC) from the measured plastic viscosity of the paste. The concrete is regarded as a two-phase composite in which the solid phase is suspended in a viscous liquid phase. The liquid matrix phase consists of cement, water and any viscosity modifying agent (VMA) to which the solids (fine and coarse aggregates and fibres) are added in succession. The predictions are shown to correlate very well with available experimental data. Comments are made on the practical usefulness of the predicted plastic viscosity in simulating the flow of SCFRC.     

Two-phase axial laminar flow in a pipe with naturally curved interface

The author considers the possibility of reducing the skin friction in pipes transmitting viscous liquid by the addition of less viscous liquid. This analysis provides the mathematical tools required to estimate the reduction in the pressure drop and power consumption which are necessary to maintain a given volumetric flow rate of the more viscous liquid. First a procedure which determines the geometry of the interface between the two, assumed immiscible, liquids is devised. It takes into account the interface tension, capillary forces and gravity. Then the two-phase Poiseuille flow problem is solved by obtaining an equivalent variational principle and applying the Rayleigh—Ritz method. The results show that when the viscosity ratio is about 1/20 one can get close to 50% reduction in the applied pressure gradient though somewhat smaller savings in the power consumption.     

含氯化镁的类离子液体结构和物理化学性质

合成了一种无色、透明、均一的氯化胆碱-尿素-氯化镁类离子液体。采用傅里叶红外光谱仪初步解析了类离子液体的结构。利用电导率仪、旋转式黏度计和密度计等仪器分别测定了该类离子液体的电导率、黏度和密度,并得出了其随温度和组成的变化关系。根据物理化学性质与温度的关系计算了Gibbs自由能、焓变和熵变等热力学数据。同时测定了类离子液体的循环伏安曲线并分析了其电化学行为。     

Gas/Flüssig-Reaktoren

Gas-liquid reactors . The gas hold-up in bubble columns increases in proportion to the gas flux density in the homogeneous flow regime and rises less than proportionally in the heterogeneous flow regime. Both the gas and the liquid axial dispersion coefficient increase with gas flow. Gas phase dispersion becomes more intensive with increasing liquid viscosity, while liquid dispersion drops slightly. Experimental results for mass transfer in low viscosity liquids show that the two-range turbulence model best fits experimental data. When aerating highly viscous Newtonian and non-Newtonian liquids, mass transfer in the liquid phase is well described by known relations valid for very low bubble-Reynolds number and very high Schmidt number.     

Mass transfer rates from bubbles in stirred tanks operating with viscous fluids

In this paper, the role of liquid viscosity on the mass transfer rates in stirred tank reactors has been theoretically studied. Liquid viscosity affects liquid diffusivity and bubble size distribution by defining bubble stability in the flow. A population balance, taking into account the effect of liquid viscosity on the coalescence and break-up closures, has been combined with Higbie–Kolmogorov's theory to predict the effect of liquid viscosity on the mass transfer rates. Experimental results from the literature for stirred tanks operating with one single Rushton turbine have been used as comparison. Different moderately viscous aqueous solutions (glucose, glycerol and millet-jelly) have been considered. Bubble break-up depends on the critical deformation of the bubbles in the continuum phase. A correlation between the Weber critical number and the liquid viscosity has been found. Once the bubble distribution is accurately determined, the volumetric mass transfer rate in viscous solutions can be predicted theoretically.     

VISCOSITY OF GLYCEROL AND ITS AQUEOUS SOLUTIONS MEASURED BY A TANK-TUBE VISCOMETER

In this paper we demonstrate several series of experiments for the measurement of viscosity of neat glycerol and its aqueous solutions using a tank-tube viscometer. Measuring viscosity of highly viscous liquids with the tank-tube viscometer is easier than other types of viscometers. This inexpensive viscometer continuously generates numerous reproducible viscosity data of highly viscous neat glycerol and its aqueous solutions under given experimental conditions such as a desired temperature and a desired concentration of water in aqueous glycerol solutions.

Fabricating the tank-tube viscometer is inexpensive, since this viscometer does not need sophisticated accessories such as a high-pressure liquid pump, a sensitive pressure sensor, and an accurate flow meter. The tank-tube viscometer consists of a large-diameter reservoir and a long, small-diameter, vertical tube.

The viscosity equation was developed under the following assumptions. Both the quasi steady state approach and the negligible friction loss due to a sudden contraction between the reservoir tank and the tube are valid. The kinetic energy of the emerging stream from the bottom end of the vertical tube of the tank-tube viscometer also is assumed to be negligible. Very viscous glycerol and its aqueous solutions were used to test the viscometer by comparing viscosity values from the viscometer with those from literatures.

The main objective of this study is to demonstrate effects of water as well as temperature on viscosity of aqueous glycerol solutions, applying experimental data of accumulated amounts of aqueous glycerol solutions at various drain durations to the newly-developed viscosity equation for the fabricated tank-tube viscometer.