Correlation of bitumen viscosity with temperature and pressure

A previous viscosity-temperature correlation (Puttagunta et al., 1992) is extended to include a pressure term and employed successfully in predicting the combined effect of temperature and pressure on the viscosity of Canadian bitumens and heavy oils. Predictions are made on new sets of data based on a single measurement of viscosity at 30°C and 101.3 kPa pressure; and the results show similar accuracy as obtained in the sets of data used in developing the correlation. The correlation yields an absolute average deviation between predicted and experimental viscosity of 4.79% and a correlation coefficient of 0.99 over a range of temperatures between 20 and 120°C and gauge pressures between 0 and 18 MPa.     

An evaluation of the pressure‐dependent melt viscosity of polyphenylsulfone

A method for the determination of pressure‐affected viscosity from capillary rheometry and pressure–volume–temperature (PVT) data was tested on polyphenylsulfone melt. Shear viscosity data evaluated at selected temperatures (345–375°C) were interlinked to the PVT data at pressures ranging from 1 to 200 MPa. According to the recently proposed correlation approach, a pressure‐dependent shear viscosity is derived from the relationship (verified on several commodity polymers) between temperature‐dependent viscosity and a free volume parameter computed using the Simha–Somcynsky equation of state. Finally, the predicted pressure‐viscosity coefficient was compared with the value obtained experimentally on a modified single piston rheometer. POLYM. ENG. SCI., 54:711–715, 2014. © 2013 Society of Plastics Engineers     

Synthesis and characterisation of branched and partially crosslinked poly(ethylene terephthalate)

In the present study, a series of branched and partially crosslinked poly(ethylene terephthalate) (PET) samples were prepared by the two‐stage melt polycondensation method, using different amounts of trimethyl trimellitate (TMT) as polyfunctional monomer. The samples were characterised with respect to intrinsic viscosity, density and gel content as well as thermal and mechanical properties. The intrinsic viscosity of the polymers ranged between 0.7 and 1.6 dl g^?1 depending on the concentration of the TMT comonomer. When TMT was used at a concentration 0.625 wt% or higher, gel formation was observed. For the sample containing 1.25 wt% TMT, almost half of the polymer was insoluble in phenol–tetrachloroethane mixture, due to extensive crosslinking. The increase of TMT content resulted in a small decrease of crystallinity attributed to branching and crosslinking, both of which restrict the organisation of the polymer chains in the crystal structure. This was reflected directly in the thermal properties of the polymers prepared. Increasing the TMT content decreased the melting point and the heat of fusion. In contrast, cold crystallization and glass transition temperatures were shifted to higher temperatures. Mechanical properties like tensile strength and elongation at break increased with increasing the content in branching agent. However, crosslinking had a negative effect on elongation at break. Copyright © 2003 Society of Chemical Industry     

Tansformation Range Viscosity Measurements Using a Thermomechanical Analyzer

A commercial thermomechanical analyzer has been adapted to determine the transformation range viscosities of very small samples using a beam-bending configuration. Three viscosity standards—NBS-710, NBS-711, and NBS-717—have been used to determine the accuracy of this technique over a wide range of temperatures. The method yielded excellent results that were independent of sample size and heating rate. The largest deviation from National Bureau of Standards data was 3.8°C at 10¹⁰ Pa's for one sample of NBS-711; the average deviation at 10¹⁰ Pa's was approximately 2°C for all samples studied. In all cases, the activation energy for viscous flow was in excellent agreement with that calculated from National Bureau of Standards data.     

Comparison of near‐infrared emission spectroscopy and the Rancimat method for the determination of oxidative stability

This work presents a comparison between a new method for the determination of the oxidative stability of edible oils at frying temperatures, based on near‐infrared emission spectroscopy (NIRES), and the Rancimat method at 110 °C. In the NIRES‐based method, the induction time (IT) is determined by means of the variation of the emission band at 2900 nm during heating at 160 °C. The comparison between the IT values obtained with the two methods for 12 samples of edible oils shows some correlation for samples of the same type once there is an agreement on the sequence of highest to lowest IT values between the methods, but a poor correlation considering all samples (correlation coefficient of 0.78). This lack of correlation demonstrates that the results obtained with the Rancimat method cannot be used as an indication of the oxidative stability, or the resistance to degradation, of edible oils at frying temperatures. The difference in the heating temperatures used in the two methods leads to 20–36 times higher IT values for the Rancimat method in relation to the NIRES‐based method, but with similar repeatabilities (2.0 and 2.8%, respectively).     

Rheological properties of endodontic sealers: the effect of time, temperature, and composition

This study was aimed to investigate the effect of different parameters such as shear rate, temperature, and time on the viscosity of four endodontic sealers. Furthermore, the effect of variations in powder to liquid ratio of two powder/liquid sealers upon their viscosity was evaluated. The tested sealers were AH Plus, Endofill, AH 26, and Epiphany self-etch (SE) sealer. As all of the tested sealers contain particles of resinous composites; shear thinning and some time-dependency of viscosity are expected. Therefore, steady shear viscosity and thixotropy behavior were assessed. The samples were examined at 25 and 37?°C with the shear rate ranged from 0.0001 to 100?s^?1. All sealers almost exhibited shear thinning behavior. At both temperatures of 25 and 37?°C, the viscosities of sealers were at the same order and ranked from the highest to the lowest as follows: Epiphany SE, AH Plus, AH 26, and Endofill. The samples with higher powder to liquid ratio of 3:1 exhibited higher viscosity compared to 2:1 ratio in both tested temperatures. With the exception of Epiphany SE and AH 26 (at shear rate less than 1?s^?1), viscosity of all sealers decreased with increasing temperature from 25 to 37?°C. All sealers exhibited time-dependent viscosity characteristics at the two examined temperatures.     

Rheological properties of concentrated polymer solution: Polybutadiene in good and θ solvents

The zero shear viscosity, η° of three polybutadiene samples having different molecular weights over a wide range of concentration (1.0–35.0% polymer) in good and θ solvents has been studied. Superposition of viscosity data has been made to give a single composite curve for each solvent by shifting them vertically by a factor (M°/M)^3.4, where M° represents the molecular weight of the reference sample. The shift factor is found to be proportional to M^3.4 in the region of higher concentration, which indicates that the 3.4-power law is valid for the data of polybutadiene. The double-logarithmic plots of relative viscosity η°_r as a function of c⁵M^3.4 yielded a single composite curve approximating a straight line with slope of unity at the higher values of the variables. The results indicate that over a considerable range of the variables (molecular weight and concentration) at a constant temperature, the relative viscosity is a single function of c⁵M^3.4. The results for double-logarithmic plots of zero shear specific viscosity η°_csp as a function of concentration confirmed those observed in polycholoroprene samples studied earlier that the η0_sp values in θ solvents at higher concentration region are found to be higher than those found in good solvents, whereas in the moderately concentrated region the values are just opposite in θ and good solvents. The viscosity crossover in θ solvents is not as sharp as is found in case of polychloroprene samples and that crossover, too, has taken place in the range of concentration of 11.7–31.6% polymer, which is comparatively higher than that of polychloroprene samples (6.06–21.0% polymer). The results indicate some relation between viscosity crossover and polymer polarity, supporting the idea of enhanced intermolecular association in poor solvents. To correlatethe viscosity data obtained in good and poor solvents, two methods, one given by Graessley and the other given by Dreval and coworkers involving the correlating variable c[η], were considered. The plots of relative viscosity η°, versus the correlating variable c[η] in benzene (good solvent) yielded one curve, but in the case of θ solvents (dioxane and isobutyl acetate), the same plots yielded three separate curves instead of a single curve, which is rather unusual. The appropriate correction on the correlating variable for chain contraction in the concentrated region in a good solvent moved the data to a common curve, especially in lower concentration region, but at the higher concentration region a slight overestimation of data seems to have been effected. On the other hand, the plots of log η as a function of correlating variable c[η] yielded a single curve for three samples in the good solvent benzene, but in poor solvents (diozane and isobutyl acetate) the same plots yielded three separate curves for three samples instead of a single curve, the reason for which is not known at present. However, the normalization of the correlating variable c[η] with Martin constant K_M reduced all experimental data of the polymer samples to a common curve. The correlation of the viscosity data by either of the two methods seems to be possible in the case of the nonpolar flexible polymer, polybutadiene.     

Shock Synthesis of Single Crystals

Shock compression of finely ground CaF₂ crystals embedded into graphite powder in cylindrical recovery ampoules was found to yield single white crystals of 0.1 mm in size within the Mach cone, where the developed temperatures/pressures are exeedingly high. The composition of these crystals CaO ⋅ 3SiO₂ ⋅ SiC is a result of chemical interactions of mixture and SiO₂ due to cumulative eruption of Si from steel walls of ampoules and its reaction with O₂ from sample pores. The atomic structure of crystals was characterized by IR spectroscopy and XRD. The formation of relatively large single crystals can take place only in the melted unloaded material.     

Effect of poly(ethylene glycol) on the solid‐state polymerization of poly(ethylene terephthalate)

Poly(ethylene glycol) (PEG) and end‐capped poly(ethylene glycol) (poly(ethylene glycol) dimethyl ether (PEGDME)) of number average molecular weight 1000 g mol^?1 was melt blended with poly(ethylene terephthalate) (PET) oligomer. NMR, DSC and WAXS techniques characterized the structure and morphology of the blends. Both these samples show reduction in T_g and similar crystallization behavior. Solid‐state polymerization (SSP) was performed on these blend samples using Sb₂O₃ as catalyst under reduced pressure at temperatures below the melting point of the samples. Inherent viscosity data indicate that for the blend sample with PEG there is enhancement of SSP rate, while for the sample with PEGDME the SSP rate is suppressed. NMR data showed that PEG is incorporated into the PET chain, while PEGDME does not react with PET. Copyright © 2005 Society of Chemical Industry     

Organosolv delignification of white‐ and brown‐rotted Eucalyptus grandis hardwood

Sound (undecayed control) and fungally‐pretreated wood samples were submitted to organosolv delignification. The cooking liquor used was methanol/water (78:22 v/v) containing CaCl₂ and MgSO₄ each at a concentration of 25 mmol dm⁻³. The cooking process was performed at 180 °C for reaction times varying from 5 to 100 min. Despite some differences in the lignin removal pattern, pseudo‐first order kinetic models permitted a prediction of delignification rate constants for all experiments. All biodegraded samples provided higher delignification rate constants than the undecayed control (2.0 × 10⁻²min⁻¹ for the undecayed control and, for example, 14.2 × 10⁻²min⁻¹ for the sample decayed by Trametes versicolor for 2.5 months). Biodegraded samples also presented significantly increased xylan removal rates. The type of biodegradation affected the behavior of wood samples under organosolv pulping. The highest delignification and xylan removal rate constants were observed in the sample decayed by T versicolor for 2.5 months (17% weight loss). However, high delignification and xylan removal rate constants were also observed in the sample decayed by Punctularia artropurpurascens for only 0.5 months (1.2% weight loss). Data obtained from a single fungal species pretreatment or data from all fungal pretreatments indicated that there is no clear correlation between the delignification constants and the wood weight or component losses. This lack of correlation suggested that the structure of residual polymers in decayed wood affects the delignification process in the organosolv pulping more than the removal extent of each individual component. © 2000 Society of Chemical Industry     

Determination of the solid fat content of commercial fats by pulsed nuclear magnetic resonance

A method and instrumentation for measuring the solid fat content is reported that is both accurate and precise. It involves using transient nuclear magnetic resonance (NMR) measurements for determining the percentage of solids in commercial shortenings and hydrogenated oils at selected temperatures. The incorporation of a tempering step at 26.7 C for all samples before measurement has improved the precision of the solids content actually measured (±0.2% solids) which approximates that of dilatometry. Duplicate measurements are not required to obtain this precision. The instrument is equipped with six 10-mm sample holders in combination with a precise variable temperature accessory system which eliminates the temperature difference between the sample and sample holder. This improved and exact temperature conditioning of samples provides better sample stability and easier handling for routine conditions of analysis. A single temperature result can be made in less than 1 hr and typical 5 temperature results obtained in 2.5 hr. Our work also indicates that tempering does influence results, the net effect being to decrease the amount of solids at temperatures less than the tempering temperature. In comparing the pulsed NMR measured solids with these measured by dilatometry, differences between methods of measurement are minimized when samples have had the same tempering and temperature history. This method provides flexibility, speed, and increased sample throughput of up to 60 samples/day. The self-contained equipment requires only 9 sq ft of space and is ready for measurements within 45 min after start-up.     

长春岭含水原油流变性研究

利用RV22型粘度计,模拟地层条件下流体状态,对长春岭107区和109区3个油样进行了试验研究,测量了不同温度、不同含水率下含水原油粘度,了解原油的流变性,研究结果表明含水原油粘度随含水率变化存在极大值（非乳化拐点）。结论可为油田的开发及原油集输提供科学依据。     

Rheological and mechanical properties of plasticized poly(vinyl chloride)

The dependence of rheological properties of a plasticized, filled poly(vinyl chloride) compound on three different methods of thermomechanical treatments has been studied. These three different states of the compound are the dry blend mixed at a maximum temperature of 93°C, the two-roll milled sample prepared at 150°C from the dry blend and the molded sample pressed at 170°C from the previously milled material. At 150°C the viscosity and elasticity of the molded sample are considerably higher than those of the dry blend and the milled sample. At higher temperatures, although their flow curves more or less merge, extrudate swell, extrudate appearance and extrudate tensile properties of the three samples vary. The mechanical and Theological properties of the quenched and annealed molded samples and those of the same compound without filler have also been investigated.     

Investigation of the dynamic mechanical behavior of polypropylene/(wood flour)/(kenaf fiber) hybrid composites

Polypropylene/(wood flour)/(kenaf fiber) hybrid composites were prepared in an internal mixer. Kenaf was considered as a fibrous filler and wood flour as a particulate filler. The lignocellulosic loading used was 50%. Dynamic mechanical thermal analysis properties such as storage modulus (E′), loss modulus (E″), damping factor (tan δ), and adhesion factor were evaluated. It was found that the adhesion factor could interpret the interfacial adhesion between lignocellulosic fillers and the plastic matrix macroscopically. This factor was affected by the type of filler used and the coupling agent concentration. The variation of storage modulus was affected more by the shape of the filler and the coupling agent concentration at higher temperatures than at temperatures below the glass transition. Owing to a higher probability of agglomeration in a sample containing 50 wt% of wood flour, the storage modulus and complex viscosity of this sample were higher than those of other samples. Cole‐Cole diagrams showed that the homogeneity of samples containing a higher amount of coupling agent was higher than that of samples with a lower concentration. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Differences in curing behavior of cocured and IPN materials

This study addressed the blending and cocuring of resole and epoxy, using NaOH and 4,4′‐diaminodiphenylmethane as curing agents. IR band shifts regarding the molecular interactions were investigated with FTIR. Exothermic peak shifts during cocuring reactions were studied with dynamic DSC. Viscosity increases were measured with a Brookfield LVT viscometer at 100°C. The dynamic mechanical properties of the cocured samples were investigated using rheometric dynamic spectroscopy (RDS). Experimental results revealed that the molecular interactions between resole and epoxy resulted in good compatibility as shown by the single damping peak in the RDS curve and the single glass transition for each cocured sample. Also apparent were accelerated curing rates, leading to shifts of the exothermic peaks to lower temperature and faster viscosity increases. Nevertheless, enhanced gel fractions and increased glass‐transition temperatures (T_g) of the samples were generally observed for this cocured system. The average molecular weight between crosslinked points calculated for the cocured materials also showed much less than the two components. These curing behaviors were quite different from those of the Interpenetrating Polymer Network (IPN) materials, which usually indicated lowered gel fractions, decreased T_g, and higher average molecular weight between crosslinkings than for components. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 963–969, 2001     

Diffusion of sulfuric acid solutions in Nylon 6,6 monitored by neutron activation analysis

Nylon 6,6 is an excellent material for the study of the diffusion mechanism and associated mechanical performance of polymers saturated with aqueous solutions of varying pH at different temperatures. The diffusion profile was studied for samples saturated at temperatures ranging from 20 to 90°C in solutions decreasing in pH from distilled water to 1.0M sulfuric acid. The presence of sulfuric acid molecules within the diffusing solutions acts to promote hydrolysis of the polyamide molecules. The degree of hydrolysis is dependent on saturation temperature and solution pH. The extent of degradation was evaluated via changes to mechanical performance and inherent viscosity and often results in a reduction of the stress at yield, flexural modulus, and inherent viscosity on increasing temperature and decreasing pH. The use of neutron activation analysis allowed for an evaluation of the sulfur content within the samples as a function of diffusing time. This demonstrated that although the mechanical performance decreases rapidly on initial exposure to the aqueous medium, this is likely due to plasticization. As diffusion time progresses, the sulfur content within the sample continues to rise to a level where the acid/water molar ratio is much higher in the sample than that of the bulk. This results in an enhancement of the degradation process as time progresses. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2476–2487, 2005     

Rheology and processability of polyamide66 filled with different‐sized and size‐distributed calcium carbonate

Two‐sized calcium carbonates (CaCO₃) were blended and filled into polyamide66 (PA66). The shear viscosity of PA66/CaCO₃ composites was measured with a capillary extrusion rheometer. The results showed that the shear viscosity of the efficient size distribution samples (PA66 was filled with 600/2500 mesh CaCO₃ blending) obviously decreased compared with that of the single‐size distribution samples (PA66 was filled with 600 or 2500 mesh CaCO₃). The shear viscosity of PA66/CaCO₃ composites at different temperatures was also studied. The results showed that the flow activation energy and flow activation entropy of the efficient size distribution samples obviously increased compared with those of the single‐size distribution samples. The change in flow activation entropy was used to explain the experimental results of shear viscosity. The processability of PA66/CaCO₃ composites was evaluated with a HAAKE torque rheometer. The results showed that the processability of the efficient size distribution samples was obviously improved and the best efficiency of processability improvement appeared in the 30 wt% CaCO₃ content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Microdielectric study of epoxy-amine systems: Gelation and relationships between conductivity and kinetics

A low-T_g epoxy-amine system, based on the diglycidyl ether of butane-1,4-diol (DGEBD) and 4,9-dioxadodecane-1,12-diamine (4D), and a high-T_g epoxy-amine system, based on diglycidyl ether of bisphenol A (DGEBA) and 4,4´-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA), were studied during isothermal curing by means of microdielectrometry. The first one, which was investigated from 40°C to 60°C, exhibits only a gelation phenomenon. The latter was studied from 80°C to 150°C. At these temperatures, gelation and vitrification phenomena occur. To observe gelation phenomenon from the dielectric curves, three different approaches were developed (inflexion point as gelation criterion, percolation theory, and correlation between conductivity and viscosity) which fail to describe the complete evolution of the epoxy-amine reactive systems during cure. This is due to the fact that at the gel point the macroscopic viscosity diverges whereas the conductivity values involve the ion motions, thus the local viscosities. So, there is no manifestation of gelation in the dielectric curves. The values of logσ/logσ₀ vs. conversion x, where σ₀ is the conductivity of the initial monomer mixture, give a single curve which can be fitted by a model proposed recently. In addition, a linear relation exists between log σ(x)/log σ₀ and glass transition temperature, T_g(x). Thus, the combination of these relations with the modified Di Benedetto equation allows predicting kinetic and dielectric behaviors knowing the glass transition temperatures, the heat capacities, and the conductivities of the initial monomer mixture and of the fully cured network.     

Physicochemical properties of pronase-treated rice glutelin

Rice glutelin protein was extracted from defatted medium-grain rice by alkali extraction followed by acid precipitation. Extracted glutelin was hydrolyzed with Pronase E, a bacterial protease, and the functional properties of hydrolysates were evaluated. Nitrogen solubility of pronase-treated glutelin protein increased from pH 2 to pH 12. Similarly, foaming and emulsion properties of hydrolyzed protein also showed improved characteristics. The emulsion activity, expressed as the turbidity of diluted emulsions, was significantly greater (P≤0.05) for hydrolyzed samples. However, turbidity for all samples decreased with increased homogenization time, indicating a decrease in the volume of dispersed oil. There were significant changes in apparent viscosity as a function of shear rate, with viscosity decreasing with increasing shear rate. The viscosity of dispersions of all hydrolyzed samples was significantly lower than that of the native sample at all shear rates tested. Enzymatic hydrolysis of rice endosperm storage glutelin proteins appeared to improve the functional characteristics of the hydrolyzed proteins.     

Correlation between electron spin resonance spectra and oil yield in eastern oil shales

Organic free radical spin concentrations were measured in 60 raw oil shale samples from north Alabama and south Tennessee and compared with Fischer assays and uranium concentrations. No correlation was found between spin concentration and oil yield for the complete set of samples. However, for a 13 sample set taken from a single core hole, a linear correlation was obtained. No correlation between spin concentration and uranium concentration was found.