粘度对表面活性剂液膜溶胀的影响

从实验和理论两方面探讨了粘度对液膜夹带溶胀及渗透溶胀的影响.当乳状液粘度超过50mPa·s时,夹带溶胀随乳状液粘度的增加而降低.膜相粘度的增加会导致渗透溶胀的减少.并提出了各粘度区估算溶胀率的数学模型,且模型值和实验数据吻合良好.     

EFFECT OF SUSPENSION VISCOSITY ON POWER CONSUMPTION IN THE AGITATION OF SOLID-LIQUID SYSTEMS

The effect of suspension viscosity on power consumption in fully baffled stirred tanks is investigated phase solid-liquid two

It is shown that the adoption of a propeir definition for the apparent viscosity makes it possible to correlate the data of single- and two-phase systems with the same power curve regardless of the flow regime.     

DRAG AND MASS TRANSFER IN SLOW NON-NEWTONIAN FLOWS OVER AN ENSEMBLE OF NEWTONIAN SPHERICAL DROPS OR BUBBLES

An approximate solution for the slow motion of an ensemble of spherical drops through a power law fluid is obtained using Happel's free-surface cell model. It is shown that the drag coefficient decreases with decrease of the flow index and that this reduction is more significant at low voidage and large viscosity ratio parameter. The effect of the pseudoplastic anomaly on the mass transfer rate is more pronounced at low voidage for large values of viscosity ratio parameter, unlike the case of a single spherical drop

The present analysis covers the whole range of values of viscosity ratio parameter from infinity (an assemblage of solid spheres) to zero (a swarm of bubbles) and reduces to the solutions for those cases already known

The results for the motion of an ensemble of spherical drops also provide the basis for proposing a tentative expression for the expansion of liquid-liquid fluidized bed at low Reynolds number.     

SBS／聚（苯乙烯－甲基丙烯酸盐）热塑性IPN熔体的流动性能

考察了组成、共混方法、温度、切变速平等因素对ＳＢＳ／聚（苯乙烯－甲基丙烯酸盐）热塑性互穿聚合物网络（ＩＰＮ）熔体流动性能的影响。结果表明，该热塑性ＩＰＮ熔体随着ＳＢＳ含量的增加，流动活化能降低；在不同的切变速率下，其表现粘度高于母体聚合物，也高于组成相似的由机械共混制备的热塑性ＩＰＮ；当ＳＢＳ含量为４０％时，其表观粘度出现极大值。     

圆管内含颗粒幂律流体的密相两相湍流

阐述了幂律流体控制方程的特点,研究了幂律流体的稠度系数和流动指数的变化对两相流动的影响.随着流动指数的增加,幂律流体在圆管中心附近的主流速度减小,同时颗粒相速度在圆管中心附近增大,而在管壁附近减小.随着稠度系数的增加,幂律流体和颗粒相的主流速度分布出现了与流动指数带来的影响相似的趋势.对带颗粒的幂律流体的两相流流动与液固两相流流动做了比较,幂律流体两相流的流体速度在管道中心附近的大部分区域比液固两相流的流体速度流动的速度大,而颗粒相的速度分布比较平坦.     

PHOTOINITIATED POLYMERIZATION OF ACRYLAMIDE AND METHACRYLAMIDE

A dilatometric technique was used to obtain kinetic data for UV-photoinitiated polymerization of acrylamide and methacrylamide. In this study, benzoinmethylether was the initiator. Two mixed-solvent systems, 30% acetic acid in water (for both monomers) and 40% methanol in water (for acrylamide only) were examined. In all three systems the rate of polymerization varies with the monomer concentration to the 1.4 to 1.5 power and to the initiator concentration to the 0.4 to 0.8 power. Energies of activation are very low, less than 1.5 kcal/mol. Molecular weights estimated from viscosity measurements support the idea that chain transfer to monomer is important in the case of methacrylamide.     

悬浮醇解过程的功率变化和流变特性

本文结合低醇解度粒状共聚改性聚乙烯醇的制造,测定了醇解过程的功率变化和流变特性,探讨了各种因素对体系功率和粘度变化的影响,目的为生产过程的控制,反应器的设计提供基础数据。     

挤出条件对聚苯乙烯熔体流动行为的影响

应用毛细管流变仪，考察了挤出条件对通用型聚苯乙烯（ＰＳ６６６）和高抗冲聚苯乙烯（ＰＳ４７０）熔体流动行为的影响，实验发现，后者的末端效应较前者显著，且其熔体的切性亦高于前者；而前者熔休的温粘性则高于后者，两试样熔体的剪切流动大体上服从幂律。此外，口型入口角对两试样熔体流动行为的影响是明显的。     

CHARACTERISATION OF COLLOIDAL GAS APHRONS

Colloidal Gas Aphrons (CGA) are finding increasing application in wastewater processing, bioseparations, etc. This article describes effect of various operating conditions such as pH, power input, impeller location, surfactant type and its concentration and viscosity of liquid on half life of CGA generated. Further, effects of various additives like, polymer, enzyme, solvents, salt, etc. are also investigated. A procedure for predicting the drainage rate of CGA has been proposed.     

EFFECTIVE VISCOSITY OF NON-NEWTONIAN FLUIDS IN A MECHANICALLY STIRRED TANK

The effective viscosity of elastic and inelastic liquids has been determined from the power consumption in stirred tanks     

EFFECTIVE VISCOSITY OF NON-NEWTONIAN FLUIDS IN A MECHANICALLY STIRRED TANK

The effective viscosity of elastic and inelastic liquids has been determined from the power consumption in stirred tanks     

HEAT TRANSFER STUDIES OF HIGHLY VISCOUS NON-NEWTONIAN FLUIDS IN VERTICAL TUBES BY FINITE ELEMENT METHOD

A numerical method capable is developed for handling steady laminar flow and heat trans-fer of a highly viscous power-law fluid whose density,viscosity,specific heat and thermalconductivity,vary with temperature.The governing equations are found to be continuity,monmentumand energy expressions.Important effects such as varying viscosity,natural convection and viscousdissipation are incorporated in the theoretical model.These equations are being attracted by employing a decoupled finite element method.Galerkin'sprinciple is used to handle the momentum and continuity equations.Consistent(SU/PG)andnon-consistent(SU)streamline upwind methods are employed for the energy equation.Comparisonof calculated results and experimental data shows good agreement.Similar results are obtained withSU and SU/PG methods.Velocity and temperature profiles which provide insights into the processare also given.     

MELT RHEOLOGICAL PROPERTIES OF TALC-FILLED ISOTACTIC POLYPROPYLENE COMPOSITES

The melt rheological properties of talc-filled isotactic polypropylene have been studied at talc concentrations of 0–33.3 vol% and at 493 K. The composites followed a power law model in the shear stress–shear rate dependence and were shear thinning. The apparent melt viscosity increased whereas the melt elasticity parameter “first normal stress difference” decreased as the talc concentration increased. Surface modification of the talc by a coupling agent LICA 38 modified the rheological properties through bonding and/or a plasticizing/lubricating effect.     

超声波气升式反应器内声压的测定

测定了在空气—水和空气—羧甲基纤维素水溶液体系中 (羧甲基纤维素含量 :2g/L)超声波气升式反应器声压随轴向位置、表观气速、黏度和超声电功率的变化。测定结果表明 ,小气速下声压在气升式反应器内的轴向分布与离开超声探头的距离有关 ,距离越远 ,声压越小 ;与气速的大小有关 ,气速越大 ,声压越小 ;与液体的黏度有关 ,黏度越大 ,声压越小 ;超声电功率越大 ,声压越大。     

火箭推进剂用硅橡胶胶粘剂：固药胶的研制

采用互贯网络改性技术，研制成功力学性能优良，粘接性能良好，有弹性，粘度小，流动性好的室温硫化固药胶，并已成功地用于某型号反垣克火箭武器。     

EPDM粘度对PP＼EPDM共混物断口形态和冲击性能的影响

用机械共混的方法制备了一系列不同ＥＰＤＭ粘度的ＰＰ／ＥＰＤＭ共混物，对其力学性能和结晶行为进行了表征，并用扫描电子显微镜（ＳＥＭ）研究了共混物冲击样条的断口形态。实验结果表明，ＥＰＤＭ粘度对共混物的冲击强度有较大影响，随着ＥＰＤＭ粘度的增大，共混物的冲击强度出现极大值，而结晶行为的变化则较小，研究共混物冲击样条的断口形态发现，共混物的冲击强度随ＥＰＤＭ粒径的变化出现极大值。     

The influence of solvent type on the viscosity of concentrated polymer solutions

The viscosity of concentrated (17.5 g/dl) solutions of cellulose acetate in 11 single solvents and in four binary solvent mixtures was related to a thermodynamic measure of solvent power. In single solvents, the specific viscosity varied from 4600 in dimethyl sulfoxide to 78,000 in diacetone alcohol, with the specific viscosity increasing with decreasing abolute value of the partial molar free energy of dilution. This behavior can be accounted for by the hypothesis that the number of chain entanglements increases with decreasing solvent power. In solvent mixtures, the specific viscosity often attains a minimum value at a composition where the average solubility parameter locus is near the center of the solubility region of the polymer.     

RHEOLOGICAL AND MIST IGNITION PROPERTIES OF DILUTE POLYMER SOLUTIONS

A spinning disc atomizer has been used to characterize the mist flammability of Jet A and diesel fuels that contain high molecular weight polymers. The critical disc velocity required to produce significant flame propagation was shown to depend on polymer concentration, molecular weight, solvent viscosity, and polymer degradation.

The viscoelastic properties of these same polymer solutions have been characterized by a maximum Darcy viscosity measured from flow in packed tubes. For the polymers discussed in this paper, the maximum Darcy viscosity was independent of the bead size or tube length; however, it was strongly affected by the same variables that affected mist flammability; i.e., polymer concentration, molecular weight, solvent viscosity, and polymer degradation.

The critical ignition velocity of dilute polymer solutions is shown to depend on the Darcy viscosity in a similar manner as observed for viscous oils. At low viscosities, the ignition velocity is only slightly affected, but the dependence grows stronger as the viscosity (both shear and Darcy) increases. A close correspondence was also shown to exist between the ignition velocity of a polymer solution with a high Darcy viscosity and the ignition velocity of a Newtonian oil with approximately the same high shear viscosity.

Numerous similarities are described between flow-induced birefringence of dilute polymer solutions with opposed capillary jets and viscoelastic resistance of dilute polymer solutions in packed tubes. These similarities suggest that the maximum Darcy viscosity is associated with a condition of almost complete extension and alignment of the polymer molecules.     

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.     

RHEOLOGICAL CHARACTERIZATION OF PYROLYTIC WOOD DERIVED OILS: EXISTENCE OF A COMPENSATION EFFECT

Detailed rheological study was made for sixteen pyrolytic wood derived oils provided by different laboratories and obtained from a wide range of liquefaction processes. Molecular characterization of these oils has been performed through gel permeation chromatography (GPC) and intrinsic viscosity [η] measurements.

All pyrolytic wood derived oils exhibit an essentially Newtonian behavior in the range of shear rate examined (10^-1 to 10³s^-1). The variation of viscosity with temperature follows an Arrhenius-type relationship. GPC chromatograms and [ η] measurements have shown the existence of a Mark-Houwink relationship between [ η] and molecular weights of the pyrolytic oils with a Mark-Houwink exponent of the order of 0.58 when tetrahydrofuran (THF) is used as solvent. Therefore the pyrolytic oils despite the diversity of the liquefaction processes all belong to a same family. Moreover, a compensation effect has been found. Because of the Newtonian character of these oils, the compensation effect allows the determination of the temperature dependence of viscosity from only one measurement of viscosity at a given temperature