The Viscosity of cottonseed oil,fractionation solvents and their solutions

Cold fractionation of cottonseed oil is made difficult by the high viscosity of the oil. This study was aimed at demonstrating the effect of solvents on the viscosity of mixtures between 0°C and 25°C with a view to facilitating the fractionation of refined cottonseed oil. The solvents used were acetone, methylethylketone, methylisobutylketone, hexane and heptane. Measurements of viscosity were carried out by means of a capillary viscometer. The ratio of the viscosity of cottonseed oil to that of pure solvents is of the order of 300. The viscosities of solutions of various ratios of solvent to oil (1/3, 1/1, 3/1) are between those of cottonseed oil and the pure solvents. The effect of the solvent/oil ratio overrides that of solvent nature. The effect of solvent in reducing the viscosity of cottonseed oil is by descending order: acetone, hexane, methylethylketone, heptane, methylisobutylketone.     

3-庚3-庚酮+乙酸乙酯、3-庚酮+乙酸丁酯、3-庚酮+TBP、MIBK+TBP二元体系的过量摩尔体积和黏度

常压下测定了3-庚酮+乙酸乙酯、3-庚酮+乙酸丁酯、3-庚酮+磷酸三丁酯（TBP）、4-甲基-2-戊酮（MIBK）+磷酸三丁酯4个二元体系在293.15～318.15 K下的密度和黏度值,计算了二元体系的过量摩尔体积V^E和过量黏度Δη,并用Redlich-Kister方程对V^E和Δη进行了关联。混合溶剂的黏度数据采用Orrick-Erbar(O-E)基团贡献法进行了关联和预测,增加了O-E方法中的(-O)₃-P=O 基团贡献值。结果表明,O-E方法可根据现有的纯溶剂的黏度数据预测得到混合溶剂的黏度,平均误差小于15%。     

正癸烷+正戊醇,+1-己醇,+庚醇二元混合物在293.15到363.15K和大气压力下的密度和粘度（英文）

Densities (ρ) and dynamic viscosities (η) for three binary mixtures of n-decane with 1-pentanol, 1-hexanol and 1-heptanol are presented at temperatures from 293.15 to 363.15 K and atmospheric pressure over the entire composition range. The density and viscosity are measured using a vibrating tube densimeter and a cylindrical Couette type rotating viscometer, respectively. Excess molar volumes (VE), viscosity deviations (Δη) and excess Gibbs energy of activation of viscous flow (ΔG*E) are calculated from the experimental measurements. Intermo-lecular and structural interactions are indicated by the sign and magnitude of these properties. Partial molar vol-umes and infinity dilution molar partial volumes are also calculated for each binary system. These results are correlated using Redlich–Kister type equations.     

Estimation of viscosities of mixed polymer solutions

A semiempirical model for estimation of viscosities of concentrated polymer solutions¹ can be applied to mixtures of polymers in a common solvent. The data required for estimation of mixture viscosity are: solvent viscosity, polymer molecular weight, density, concentration, and intrinsic viscosity in the particular solvent. Calculated and experimental viscosities agree to within a few per cent for the relatively nonpolar systems for which comparative data are available. The model does not appear to be adequate for mixtures in which there are extensive hydrogen-bonding interactions. Results of the new model are equivalent to those of an empirical equation² reported to be effective for fairly concentrated binary polymer mixtures. Specific interactions between polymeric solutes can be conveniently assessed by comparing measured mixture viscosity to that calculated from the model presented. It is not clear, however, that such assessments have any fundamental significance, since the interactions which are calculated depend on the assumptions inherent in the estimation of the “ideal” mixture viscosity. The same reservations apply to other models which have been proposed for this purpose.     

The rheological characterization of fluorinated thermoplastics using squeezing flow viscometry

A squeezing flow viscometer was developed to characterize the rheological properties of luorinated thermoplastics. The viscosities of CTFE (polychlorotrifluorethylene) and FEP (a copolymer of tetrafluoroethylene and hexafluoropropylene) were determined using the viscometer by assuming that the shear-rate dependent viscosity can be described by a power-law, a truncated power-law, or an Ellis model. The results were in agreement with the viscosities measured with steady shear cone-and-plate viscometry and oscillatory cone-and-plate rheometry. Although the squeezing flow behavior of the polymers can be well explained by the purely viscous models, the power-law model is valid only for a limited range of shear-rates whereas the other two models are useful over a relatively wide range.     

Ultrasonic degradation of solutions of poly(vinyl acetate) in tetrahydrofuran

The ultrasonic degradation of poly(vinyl acetate) (PVAc) solutions was carried out in tetrahydrofuran (THF) at 20, 25, 30, and 35°C to investigate the effects of the temperature and solution concentration on the rate of degradation. The degradation kinetics were studied with viscometry. The calculated rate constants indicated that the degradation rate of the PVAc solutions decreased as the temperature and solution concentration increased. The calculated rate constants were correlated in terms of the concentration, temperature, vapor pressure of THF, and relative viscosity of the PVAc solutions. This degradation behavior was interpreted in terms of the vapor pressure of THF and the viscosity and concentration of the polymer solutions. With increasing temperature, the vapor pressure of the solvent increased, and so the vapor entered the cavitation bubbles during their growth. This caused a reduction in the collapsing shock because of a cushioning effect; therefore, the rate of degradation decreased. As the solution concentration increased, the viscosity increased and caused a reduction in the cavitation efficiency, and so the rate of degradation decreased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2373–2376, 2005     

Rheology of vegetable oil analogs and triglycerides

The rheological properties of two complex mixtures of short-chain triglycerides were experimentally determined. Dynamic or absolute viscosities of the mixtures were measured for shear rates of 0.32 to 64.69 s⁻¹ at temperatures between 25 and 80°C. The compositions of the mixtures were based on the oil of the plant species Cuphea viscosissima VS-320, a natural source of short-chain triglycerides. The dynamic viscosities of these mixtures were compared to those of a traditional vegetable oil (peanut oil) and diesel fuel. The results of this comparison were used to make estimates of the performance of such triglyceride mixtures as diesel fuel substitutes, since viscosity can be a key indicator of fuel performance for possible substitute diesel fuels. The crystallization temperatures of these two mixtures were also determined experimentally, and the effects of crystallization on fuel performance were projected. Additionally, the dynamic viscosities of pure triglycerides from C6∶0 to C18∶0 at 75°C were plotted vs. chain length. These viscosities were measured at high shear rates (>6 s⁻¹) where dynamic viscosity is shear-independent. An obvious trend in the relationship between triglyceride chain length and viscosity was observed. A second-order regression was used to obtain an equation for this relationship. This equation was used as a model for composition dependence of viscosity. This model was applied to the viscosities of the triglyceride mixtures examined here. There was good agreement between the model and the actual, measured viscosity values determined in this study.     

N,N-二甲基甲酰胺+醇二元混合物的黏度测定与关联

在288.15~313.15 K和常压下,利用乌氏黏度计测定了N,N-二甲基甲酰胺（DMF）分别与乙醇、丙醇、乙二醇和1,2-丙二醇组成的二元系全浓度范围内的黏度,计算了过量黏度△η和过量流动活化自由能△G^*E。用Redlich-Kister方程对过量黏度进行了关联;用黏度模型如Frenkel方程,Grunberg-Nissan方程,Katti-Chaudhari方程和McAllister方程对实验黏度数据进行了关联和预测,并利用Eyring理论方法计算了流动活化自由能、活化焓和活化熵等热力学函数。结果表明,4个二元系的过量黏度和过量流动活化自由能均为负值,且都随温度降低而偏差增大。过量黏度最低值均发生在DMF摩尔分数约为0.3处。McAllister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。比较并分析了DMF与一元醇和二元醇之间分子相互作用的差异。。     

Characterization of rheological properties of colloidal zirconia

Dynamic viscosity of aqueous suspensions of nanosized zirconia (ZrO₂) have been studied for the low volume fraction range. The specific surface area of dry powder was determined from the BET method. The zeta potential of zirconia particles as a function of pH was measured by the microelectrophoretic method. The isoelectric point found in this way was 4.7. The particle density in aqueous suspensions was found by the dilution method. The dynamic viscosity of suspensions was measured by using a capillary viscometer that eliminated the sedimentation effects. Experimental data showed that for dilute zirconia suspension, the relative viscosity increased more rapidly with the volume fraction than that the Einstein formula predicts. This allowed one to calculate the specific hydrodynamic volume of particles in the suspensions and their apparent density. It was found that particles forming zirconia suspensions were composed of aggregates having porosity of 40–50%. The size of the primary particles forming these aggregates was 0.2 μm that agrees well with the BET specific surface data. The influence of an anionic polyelectrolyte:polysodium 4-styrenesulfonate (PSS) on zirconia suspension viscosity also was studied. First the PSS viscosity alone was measured as a function of its volume fraction for various ionic strength of the solutions. The data were interpreted in terms of the flexible rod model of the polyelectrolyte. Then, the viscosity of ZrO₂ in PSS solutions of fixed concentration was measured as a function of the concentration of zirconia. It was revealed that the viscosity of the mixtures was proportional to the product of the zirconia and polyelectrolyte viscosities taken separately.     

Viscoelastic characterization of uncured NR/Cel II compositions

In this work three types of equipments were used, namely, rubber process analyzer (RPA 2000), Mooney viscometer, and dynamic mechanical thermal analyzer, to characterize natural rubber mixtures containing different amounts of regenerated celulose (Cel II) as filler. The RPA 2000 is a new dynamic rheological tester that can analyze raw polymers and masterbatches as well as rubber compounds before, during, and after cure. The Mooney viscometer is probably the most widely used method for measuring shearing viscosity of unvulcanized rubbers or rubber compositions. DMTA is used to assess filler–rubber interactions. In the present investigation, RPA tests on unvulcanized natural rubber and regenerated cellulose (Cel II) mixtures were carried out using strain and frequency sweeps, and the Mooney viscosities were determined using the relaxation accessory and the small rotor. DMTA data were taken at a fixed frequency and temperature sweep. The filler content was increased up to 30 phr. Compositions were prepared by cocoagulation of natural latex and cellulose xanthate mixtures. The results showed a good dispersion of the filler in the rubber matrix and its large influence on rheological and dynamic properties of the resulting compositions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2125–2131, 2005     

The differential viscometer. I. A new approach to the measurement of specific viscosities of polymer solutions

A new type of solution viscometer is described that measures the specific viscosity directly. This is accomplished with a balanced network of four capillaries arranged in a manner analogous to a Wheatstone bridge. A differential pressure transducer measures the increase in pressure across the bridge when a solution is injected into one of the capillaries while solvent flows continuously in the other three capillaries. The differential pressure is proportional to the specific viscosity of the solution. The differential viscometer is about 10 times more sensitive than a conventional glass tube viscometer, permitting precise measurements of specific viscosities of 0.01 or less. The measurements are also inherently fast, averaging about 3 min per sample. Precision is about 1% RSD. Accuracy was investigated by running standard solutions of sucrose in water, polystyrenes in toluene, and polyethylenes in decalin. The agreement was within 2–3% of the standard values in most cases.     

The effect of CO2 on the viscosity of polystyrene/limonene solutions

We demonstrate the use of a quartz crystal viscometer to determine the viscosity of solutions of polystyrene in limonene in the presence of high pressure carbon dioxide. These measurements were determined up to 50 bar in the range of temperature from 20 to 40 °C and at 0.025, 0.05, 0.1, 0.2, 0.3 and 0.4 g PS per ml of limonene. The selected variables of study (pressure, temperature and concentration) were statistically significant over the range of viscosity studied. The viscosities of the solutions at all loadings were found to decrease with increasing temperature and pressure while the plastising effect of CO₂ prevailing over the hydrostatic pressure applied by the gas. The flow activation energies of the system were obtained from an Arrhenius fitting of the experimental data reaching a maximum of 40 kJ/mol. An empirical model correlating the viscosity of the mixtures to pressure and temperature was developed in order to interpolate and extrapolate in the study region or in a range close to the working limits. Finally, the viscosity data were used to determine the solvent quality and to quantify the demixing points of the mixtures.     

Inverse gas chromatography study of polyvinylacetate–solvent and polyethylene–solvent systems

In this article, the thermodynamic behavior of polyvinylacetate (PVAc)–solvent, and polyethylene (PE)–solvent mixtures have been studied by determining the thermodynamic sorption parameters (enthalpy, entropy, and free energy), the mass‐based solvent activity coefficients (Ω) and the Flory Huggins parameters (χ), by means of inverse gas chromatography (IGC) measurements. According to the Flory Huggins parameters of the PE–solvent mixtures, determined between 40 and 60°C the compatibility (the ability to interact with each other) of this polymer with the different types of solvents follows this order: dispersion solvents > polar solvents > association solvents. In the case of PVAc mixtures, the thermodynamic parameters were determined between 60 and 80°C, only for polar‐type and association‐type solvents due to, in the studied temperature range, the retention diagrams of dispersion solvents show that there are not bulk interactions. The Hildebrand solubility parameters of both polymers were also determined, according to Guillet procedure. The higher values of PVAc material (14.1 MPa^0.5 for PE and 19.8 MPa^0.5 for PVAc, at 60°C) are related to the strong interactions of vinyl acetate monomer. POLYM. ENG. SCI., 56:36–43, 2016. © 2015 Society of Plastics Engineers     

Viscosity reduction of polymeric liquid by dissolved carbon dioxide

The viscosities of polydimethylsiloxane (PDMS)/CO₂ solutions were measured over the range of pressures of 1–3 MPa and at the ambient temperature. The viscosities were measured by using a specially designed falling ball viscometer (FBV). The Stokes equation was used to determine the viscosities and the Stokes force expressing the viscous drag of the sphere was corrected for the effect of the lateral cylindrical wall. The Kelley-Bueche (KB) free-volume treatment of the viscosities of polymeric solutions was modified to account for the gas solvent and applied to interpret our data on PDMS/CO₂ systems. It was shown that the theoretical equation, based on the assumption of the additivity of free volumes of the components, was capable of predicting with remarkable accuracy the concentration and pressure dependence of the viscosities of the investigated polymeric solutions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 459–466, 1997     

Comparison of relative viscosity measurement of polyvinylpyrrolidone in water by glass capillary viscometer and differential dual‐capillary viscometer

The relative viscosity (RV) of polyvinylpyrrolidone (PVP) with different molecular weights was measured with a glass capillary viscometer and with a differential dual‐capillary viscometer in water at different concentrations. For the differential dual‐capillary viscometer, RV increases with a decreasing flow rate, especially for high molecular weight PVP at a 1% concentration. A good agreement in the RV between the two methods can be obtained for PVP with different molecular weights and at various concentrations if an appropriate flow rate is selected for the differential dual‐capillary viscometer. Special precaution is needed when using the differential dual‐capillary viscometer to measure the viscosity of a pure solvent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1312–1315, 2002     

均三甲苯/二异丁基甲醇混合溶剂黏度测定及关联

采用乌氏黏度仪,在常压和293.15～323.15 K温度范围内测定了均三甲苯与二异丁基甲醇混合溶剂以及两种纯溶剂的黏度,计算了不同温度和组成下混合溶剂的超额黏度。用Redlich-Kister方程对超额黏度进行了关联;用Andrade方程、UNIFA-VISCO模型以及Grunberg-Nissan模型对黏度进行了关联与预测。结果表明,混合溶剂的黏度随温度升高和均三甲苯含量增加而减小。超额黏度均为负值,且随均三甲苯含量增加呈U形变化,约在均三甲苯摩尔分数为0.3时达到最低。Grunberg-Nissan模型对黏度数据的关联和预测性最好,预测值与实测值的最大和平均相对偏差分别为12.96%和5.74%。     

Viscosities of fatty acids and methylated fatty acids saturated with supercritical carbon dioxide

The viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO₂) were measured with a high-pressure capillary viscometer. Oleic acid and linoleic acid were evaluated from 85 to 350 bar at 40 and 60°C. The more SC-CO₂-soluble methylated derivatives of these fatty acids were evaluated from 90 to 170 bar at 40 and 60°C. The complex mixture of anhydrous milk fat (AMF) was evaluated from 100–310 bar at 40°C. The viscosities of the methylated fatty acids saturated with SC-CO₂ decreased between 5 and 10 times when the pressure increased from 1 to 80 bar, followed by a further decrease by a factor of 2 to 3 when the pressure was increased from 80 to 180 bar. The viscosities of the fatty acids and AMF saturated with SC-CO₂ had viscosity reduction similar to the methylated fatty acids between 1 and 80 bar, but they decreased much less between 80 and 350 bar. At constant pressure, the viscosity of the fatty acids and AMF decreased with increasing temperature, whereas the viscosity of the methylated fatty acids increased with increasing temperature. The lipid/SC-CO₂ mixtures were Newtonian, and their viscosities were best interpreted by using the mass concentration of dissolved SC-CO₂ in the lipids and the pure component viscosities.     

Viscous behavior of some liquid rubber resins

The flow behavior of several low molecular weight polymers has been studied as a function of shear rate and temperature. These polymers, which had terminating hydroxyl or bromine groups, included homopolymers of polybutadiene and acrylonitrile–butadiene and styrene–butadiene copolymers. Viscosity was measured as a function of shear rate for the temperature range 25°–35°C, and the limiting zero shear viscosities were obtained for the range 25°–60°C. A cone plate viscometer was employed to measure the effect of shear rate on viscosity, and a Brookfield viscometer was used to verify the zero-shear rate values. A tendency of the fluid to flow out of the cone-plate gap was observed for some of the materials studied. From the viscosity data, characteristic times were estimated, and the data were compared with two constitutive equations. A modified Arrhenius equation was fitted to the zero-shear viscosity data. In the case of one material, it was possible to test the Nakajima relationship between viscosity and molecular weight distribution. The dependence of material parameters on temperature is discussed in detail.     

Influence of different synthesis processes on the rheology of PVAc–MMT–DOAB exfoliated nano-composite

It is very helpful to guide design production and processing conditions for polymer-based inorganic or organic nano-composites by investigating their rheology. In this study, an intercalated nano-composite of montmorillonite (MMT)-dioctadecyl dimethyl ammonium bromide (DOAB) was added and reacted with vinyl acetate (VAc) to form the exfoliated nano-composite of polyvinyl acetate (PVAc)–MMT–DOAB through five different synthesis processes. The MMT–DOAB was exfoliated into nano-particles of layers or sheets and dispersed randomly in PVAc matrix. The different synthesis processes affected the dispersion and apparent viscosity of PVAc and PVAc–MMT–DOAB. With the polymerization time shortening and the water decreasing, the dispersion got bad and the apparent viscosity increased. PVAc and PVAc–MMT–DOAB were pseudo-plastic non-Newtonian fluids and both possessed the normal stress effect (Weissenberg effect) that is also called the pole-climbing phenomenon. By the help of the apparent viscosity analyzed using the power-law function equation, Newtonian fluid flow equation and Cross-Williamson model viscous equation, the different synthesis processes and MMT–DOAB had a certain effect on the rheology of PVAc and PVAc–MMT–DOAB. With the change of different synthesis processes and the increase of MMT–DOAB content in the synthesis system, the estimated molecular weight of PVAc–MMT–DOAB was also increased accordingly.     

A new analytical method to calculate intrinsic viscosity and viscosity constants of polymer–solvent systems

Experimental viscosities were measured by Schott Gerate viscometer at 30 °C for polystyrene–chloroform and polycaprolactum–benzene systems. These data were analyzed by a newly developed analytical method to calculate intrinsic viscosity and viscosity constants. The analytical method was compared with the graphical as well as the least squares methods and the new analytical method is better than the graphical method because it avoids personal errors that might arise in reading the intercept and slope values from the reduced viscosity versus concentration plots. Furthermore, the analytical method is as effective as the least squares method, but provides better insights while choosing the experimental viscosity values. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 283–290, 2002