Activation Energy Of Viscous Flow Research Articles

Viscosity determination of the biomass slag in the SiO2-CaO-K2O system based on the bond distribution

The slag mobility is a key factor influencing the slag tapping process during the slagging gasification of biomass. However, the viscosity model suitable for the biomass slag (relevant to the SiO2-CaO-K2O system) has not been reported yet. This study firstly proposed an Arrhenius-type viscosity model based on the bond distribution in biomass slag. The bond information of the biomass slag was determined by61 thermodynamic modelling. The quantified relation between the slag composition (SiO2, CaO, and K2O) and bond distribution (Si-Si-O-O, Si-Ca-O-O, and Si-K-O-O), and the relation between the bond distribution and activation energy of viscous flow (Ea) or pre-exponential factor (A) were established, respectively. The standard deviations of our model are 1.71 Pa·s in the 0–100 Pa·s and 0.61 Pa·s in the 2.5–25 Pa·s, respectively. The newly built viscosity model shows superior prediction performance than the empirically viscosity models, and owns better performance than the FactSage model in the optimal viscosity range (2.5–25 Pa·s) of the smooth slag tapping process.

Balancing the sustainable component of ethylene-vinyl acetate for achieved better compatibility improvement of wax-based warm mix additives in bitumen

The ethylene-vinyl acetate (EVA) polymers are always doped into waxy bitumen to inhibit network of wax crystals in bitumen. However, the compatibility improvement behaviors between wax-based warm mix (WWM) additives and bitumen by EVA are not clear, and the sustainable components of EVA for corresponding WWM additives to achieve better compatibility improvement are also not determined. This paper investigated compatibility improvement behaviors between commonly used WWM additives and bitumen after the addition of EVA to obtain sustainable components of EVA through experimental method of activation energy of viscous flow (AEVF) and density function theory-molecular dynamic (DFT-MD) calculations. The results show that the repulsions between the end of main-chain with highest electronegativity in WWM additives and polar molecules of EVA can alleviate the aggregation behaviors of WWM additives and EVA displays the best and worst compatibility improvements for additives with shortest and longest carbon chains, respectively. The dispersed asphaltenes combined with EVA can form the composite wax inhibitors (WIs) systems to increase diffusion coefficient and reduce percentage increment values of cohesive energy density (CED) to further disrupt ordered degree of WWM additives. On this basis, the sustainable carbon numbers of main-chain for EVA that are slightly less than average carbon numbers of WWM additives will help to better improve the compatibility of WWM additives. This investigation can provide the inspiration on how to choose the sustainable components of EVA to achieve high-efficiency compatibility improvement for corresponding warm mix asphalts (WMAs) with different average carbon numbers.

Influence of Cr2O3 on the Viscous Flow Behavior and Structure of Cr‐Containing Molten Titanium Slag

Herein, the influence of Cr2O3 on the viscous flow behavior and structure of Cr‐containing molten titanium slag is investigated in this work. The melting and viscosity properties are studied by hemisphere method and rotating cylinder method, respectively. In addition, the structure of Cr‐containing molten titanium slag is investigated by Raman spectroscopy. It is shown in the results that the melting temperature and viscosity both increase with the increase of Cr2O3 content. The activation energy for viscous flow increases with increasing Cr2O3 content, which is in the same trend as viscosity. When the Cr2O3 content increases from 0% to 3%, the simpler 6‐coordinated Ti4+ and TiO44− monomer unit transformed into more complex O–Ti–O deformation and Ti2O64− chain unit. Furthermore, the fraction of relatively complex silicate structural units shows an increasing trend. Cr2O3 behaves as a network former and enhances the degree of polymerization of network structure, and the variation of Cr‐containing molten titanium slag structure is consistent with the increasing trend of viscosity.

Study on rheological behavior of polystyrene‐polyisoprene‐polystyrene around viscous flow transformation: Effect of polystyrene block content and molecular weight

AbstractThe flow behavior of triblock copolymer polystyrene‐polyisoprene‐polystyrene (SIS) was different below and above the viscous flow transition temperature (Tf). The study investigated the relationship between molecular structure (molecular weight and polystyrene block content) and the macroscopic rheological properties of SIS melt around Tf via capillary rheometer. The results indicated that below the Tf, shear viscosity of SIS melt was controlled by the polystyrene (PS) block content. On the other hand, above the Tf, shear viscosity was controlled by molecular weight. The rheological phenomena were explained based on the state change of the PS domains below and above Tf. The effect of PS block content on the viscous flow activation energy (Eη) and pressure drop of SIS melt was also investigated.

Thermal hysteresis phenomena in aqueous xanthan gum solutions

The anionic hydrocolloid polysaccharide xanthan gum is widely used in the food and petroleum industries (among others) as a viscosity enhancement polymer due to its high viscosity at low concentrations and moderate temperatures. The physical properties of microbial polysaccharide xanthan gum aqueous solutions were investigated using temperature dependent viscosity measurements. Specifically, the effect of thermal history on the solution viscosity was investigated. Heating and cooling cycles were assessed in two ways, by using a “sawtooth” and “triangle” pattern, which essentially differed in the rates of cooling. The sawtooth method used a cooling rate of 2.0 °C min−1 whereas the triangle pattern had a cooling rate of 0.20 °C min−1. The sawtooth cooling rate was controlled by the speed at which the Peltier device could cool the sample, and the triangle rate was governed by the time required to measure the viscosity at each temperature on return to the initial value. Cycles measured using the sawtooth pattern for 16 mg/kg xanthan gum in water showed an 8–10% overall decrease in the viscosity over four complete cycles. Comparatively, at 320 mg/kg the xanthan gum solution showed a 25% decrease in viscosity over four cycles. The observed temperature dependent viscosity variation suggested minor modifications in the physical network structure of xanthan gum. When using a triangle heating/cooling pattern, the overall decrease in the xanthan gum solution viscosity was 5–7% for 16 mg/kg and only 10% change for 320 mg/kg solutions. The activation energy of viscous flow for the aqueous xanthan gum solutions by either method was ∼15.0 kJ/mol under all conditions. The data showed that temperature and heating cycles influence xanthan gum viscosity and thermal history, which depends more strongly on xanthan gum concentration than solution temperature.

Thermo-kinetic and structural characterization of Ce-doped glasses based on Bioglass 45S5

Thermo-kinetic behavior of Ce-doped 45S5 bioactive glass (addition of CeO2 up to 1.5 mol.%) was explored by means of calorimetry and thermomechanical analysis. The apparent activation energy of structural relaxation was estimated to vary in the 540–670 kJ mol−1 range. The relaxation process exhibited broad distribution of relaxation times and the relaxation motions were found to only weakly depend on the material's structure. The activation energy of viscous flow was found to vary in the 585–615 kJ mol−1 range; the viscosity itself showed Arrhenian behavior within 107–1011 Pa s. Thermal stability of the glasses was found to be non-monotonous and generally very low, with the most stable glass composition being 45S5 + 0.5 mol.% CeO2. The cold crystallization was found to behave autocatalytically, with the activation energy decreasing from 360 to 310 kJ mol−1 with the gradual addition of CeO2. While the bulk glasses were crystallization-resistant up to 620 °C, the powdered material with CeO2 content ≥1 mol.% was predicted to crystallize even at temperatures slightly above the glass transition temperature.

Influence of Zn2+ catalyst stoichiometry on curing dynamics and stress relaxation of polyester-based epoxy vitrimer

In the classical “covalent adaptive network” constructed by diglycidyl ether of bisphenol A (DGEBA) and crosslinking agent glutaric anhydride (GA), Zn-based catalyst greatly affects the curing crosslinking reaction and dynamic transesterification reaction. Herein, the crucial roles of Zn(Ac)2 catalyst in the curing dynamics and stress relaxation were studied. The results reveal that increasing the content of Zn(Ac)2 can significantly reduce the reaction activation energy (Eα) at initial stage, thus effectively promoting the curing crosslinking reaction. The analyses of dynamic properties suggest that although stress relation time (τ) can be shortened by increasing catalyst content, the high content of catalyst would lead a fast transesterification rate at relatively low temperature, which is adverse to the mechanical stability of vitrimer resin at operating temperature. By comparison, the vitrimer resin with modest catalyst content (mole ratio of 1:0.5:0.05) shows a highest viscous flow activation energy (Eτ), i.e., excellent dimensional stability and processability. Besides, the crosslinking density of resin was significantly affected by the content of catalyst. Since the competitive catalytic effects on curing cross-linking reaction and subsequent transesterification, the vitrimer resin of 1:0.5:0.05 exihits the highest crosslinking density (1855 mol/m3), so that it has highest Tg (79 °C) and tensile strength (72 MPa).

Effect of TiO2 on viscosity and structure for CaO-SiO2-Al2O3-based mold flux

The viscosity of CaO-SiO2-Al2O3-MgO-Na2O-CaF2-(TiO2) was measured by the rotating column method, and the viscosity, break temperature and viscous flow activation energy of the slag were analyzed based on the results. The effect of TiO2 content on the structure of the slag was studied by Raman spectroscopy. The results show that with the increase of TiO2 content in CaO-SiO2-Al2O3-based mold flux, the viscosity of mold flux increases, the break temperature increases from 1418 K to 1535 K, and the viscous flow activation energy changes little. At high temperature, TiO2 can depolymerize the [Si-O] and enter into the network structure as [Ti-O], which increases the frictional resistance to the viscous flow of the mold flux. At the same time, the crystallization temperature and viscosity of the slag is increased.

Effect of MgO/Al2O3 on Viscosity and Thermodynamic Properties of High-Titanium Slag Containing Chlorine

In order to study the effect of the change of MgO/Al2O3 on the viscosity and thermodynamic properties of the chlorinated blast-furnace slag, the CaO-SiO2-MgO-Al2O3-TiO2-CaCl2 slag system was taken as the research object, and the viscosity change rule of the chlorinated high-titanium slag was studied by using the rotating cylinder method. The thermal stability of the chlorinated high-titanium slag was quantitatively analyzed by calculating the extreme heat release rate (EHRS) of the chlorinated high-titanium slag. At the same time, the qualitative and quantitative analysis of the high-titanium slag containing chlorine was carried out by combining FTIR and Raman spectroscopy, and the mechanism of the influence of MgO/Al2O3 on the viscous flow characteristics of the high-titanium slag containing chlorine was revealed. The results show that when the alkalinity (R2) of the fixed slag is 1.15, when MgO/Al2O3 is in the range of 0.40–0.66, the viscosity of the high-titanium slag containing chlorine presents a significant decreasing trend with the gradual increase of MgO/Al2O3, and the viscous flow activation energy of the slag decreases from 98.75kJ · mol−1 to 95.21kJ · mol−1. The heat capacity and enthalpy change of slag decrease with the increase of MgO/Al2O3, but the change rule of slag extreme heat release is opposite to that of heat capacity and enthalpy change. When MgO/Al2O3 increases, the slag extreme heat release increases from 13.413 kJ to 15.172 kJ. The content of simple structural units Q0 and Q1 of silicate tetrahedron in the slag gradually increases, the content of complex structural units Q2 and Q3 gradually decreases, and the average amount of non-bridging oxygen decreases from 1.94 to 1.79, indicating that Al2O3 acts as a network maker in the internal network structure of the slag. The increase of MgO/Al2O3 destroys the complex silicate tetrahedron structure in the slag, reducing the degree of polymerization of the slag silicate network. In addition, the transmissivity of [SiO4]4− tetrahedron, [AlO4]4− tetrahedron and T-O-T bond bending vibration band in the slag shows a decreasing trend. Within the scope of the experiment, the increase of MgO/Al2O3 can effectively improve the fluidity of the chlorine-containing blast-furnace slag and improve the thermal stability of the chlorine-containing blast-furnace slag.

Effect of phosphorus on viscosity-temperature behavior of high-sodium coal ash slag

Co-gasification of P-rich fuels and coal would reduce the large-scale usage of fossil fuels and pollution emissions, and fit the “carbon neutrality” goal in 2060. However, the effect of phosphorus on the viscosity-temperature behavior and structure of high-sodium coal ash slag is not yet completely characterized. In this work, the effect of phosphorus on the viscosity and structure of slag was investigated, and the crystallization tendency was also elevated. Results indicate that the high-sodium coal ash slag has a low viscosity as the Na2O can provide O2− ions and break Si-O-Si bonds, leading to decreasing the slag viscosity. The slag viscosity gradually increases as the PO43−/Na molar ratio increases because the phosphorus acts as a network former and enhances the slag viscosity. The temperature of critical viscosity rises from 1206 °C to 1305 °C and 1127 °C to 1207 °C, respectively, for Group 1 and Group 2 when the PO43−/Na molar ratio rises from 0/0 to 2/1. With the addition of phosphorus, the cations of Na are removed from the silicate network and form Na phosphate complexes and Si-O-Si linkages, and the content of Q3(Si) and Q4(Si) units increases while the contents of Q0(Si), Q1(Si), and Q2(Si) units decrease, increasing the slag viscosity. In addition, the Si-O-P and P-O-P linkages are formed due to the phosphorus atoms being introduced into the slag structure. Resulting in decreases the content of non-bridging oxygen and rises the degree of polymerization of slag. Furthermore, the viscous flow activation energy of slag increases while reducing the crystallization tendency after the application of phosphorus.

Volumetric and viscometric properties of monoethanolamine (MEA) + 3-dimethylamino-1-propanol (3DMA1P) + H2O at T = (293.15 to 333.15) K

Densities and viscosities were measured for binary solutions MEA (monoethanolamine) + 3DMA1P (3-dimethylamino-1-propanol), 3DMA1P + H2O and ternary solutions MEA + 3DMA1P + H2O at P = 0.101 MPa, T = 293.15 K ∼ 333.15 K. Based on the experimental densities of solutions, the volume properties of the excess molar volume, partial molar volume, apparent molar volume and limiting partial molar volume were calculated. Moreover, the viscosity deviation and viscous flow activation energy were calculated based on the experimental viscosity. Additionally, the intermolecular interactions of the mixed solutions were analyzed and discussed, and the Redlich-Kister equation was used to correlate the excess molar volume and viscosity deviation of the binary solutions.

Protein-protein interactions in solutions of monoclonal antibodies probed by the dependence of the high-frequency viscosity on temperature and concentration.

Using a quartz crystal microbalance with dissipation monitoring (QCM-D), the complex high-frequency viscosity,  = η' - iη'', of concentrated solutions of a monoclonal antibody (mAb) was studied with respect to its dependence on temperature, T, and concentration, c. Lysozyme and bovine serum albumin (BSA) served as reference materials. Viscoelasticity was found for the mAb solution, while the reference materials behaved like Newtonian liquids. The QCM-D probes the solution's dynamics on the time scale of a few tens of nanoseconds. The processes of relaxation accessed with the QCM-D are not amenable to standard viscometry. The inverse loss tangent at 15 MHz (equal to η''/η' at 15 MHz, quantifying the elastic contribution to the oscillatory stress) was between 0.1 and 0.5 for the concentrated mAb solutions. It decreased with increasing temperature and decreasing pH. Activation energies of viscous flow, Ea,η, were derived from the functions η'(T). Ea,η was found to be higher for the mAb solutions than for water. No such increase was found for the reference materials. This difference evidences protein-protein interactions (PPIs) between the mAb molecules, which do not exist in the same way for lysozyme and BSA. The excipients citrate and arginine did not noticeably affect the mAb's high-frequency viscosity as determined with the QCM-D.

Залежність «в’язкість – температура» вбирних олив різних виробників.

Coal tar wash oil is the main absorbent for removing benzene hydrocarbons from coke gas and is also used in various industries. Determination of oil viscosity is important primarily for precise regulation of the flow of the substance, given that a low viscosity value indicates less resistance to movement and higher movement speed. The value of the oil viscosity index in the process of its use for the recovery of benzene hydrocarbons from coke gas acquires the status of an integral criterion for evaluating the properties of the oil as an absorbent. For engineering and technological calculations of the viscosity of wash oil, coke chemists of Ukraine use two reference sources of information, although the conditions and materials for obtaining data are not specified in these sources. In the current period in Ukraine, in connection with the limitation of the production of wash oil, the issue of purchasing foreign samples of oil of a wide range of quality is being considered. To determine and interpret the temperature dependence of viscosity for samples of foreign and domestic oils of different composition, experiments were performed to measure dynamic viscosity using a Brookfield DV2T rotational rheometer with a controlled shear rate. β-methyl naphthalene was selected as the additive that most reduces oil viscosity, and diphenylene oxide as the additive that most increases oil viscosity. Among the experimentally obtained dependences, the maximum viscosity values are obtained by the oil produced in Ukraine on a single-column unit, and the minimum values by the oil produced abroad, artificially saturated with β-methyl naphthalene. The nature of the experimentally obtained curves is approximately the same, only the heavier domestic oil is more temperature-dependent at the beginning of the temperature range taken for research. Foreign samples of absorbent oil with a rather narrow boiling range have a lower viscosity level than oils of Ukrainian producers with a wider boiling range. Keywords: wash oil, viscosity, temperature dependence, aromatic components, viscous flow activation energy. Corresponding author: Artem L. Bannikov, e-mail: artiksmartik@gmail.com

Role of P2O5 in the viscous behavior and structure of yellow phosphorus slag

To clarify the role of P2O5 in the fluidity of yellow phosphorus slag during the centrifugal granulation process, the viscosity and structure of slag with various P2O5 contents were researched. It showed that increasing P2O5 content from 1.38wt% to 5.80wt% enhanced the slag viscosity and activation energy for viscous flow, which reduced the slag fluidity. P2O5 in slag existed as QP0 and QP1 units whose proportions were about 0.89 and 0.11, respectively, irrespective of the P2O5 contents. The introduced P2O5 promoted the polymerization of silicate structure because the metal cations coordinated by non-bridging oxygens in silicate structure became connected with the phosphate structure. P2O5 addition encouraged the conversion of [AlO4] units into [AlO5] units and reduced the polymerization degree of aluminate structure. The variations in the polymerization degree of silicate and aluminate structure played a competitive role in determining the slag viscosity, and the silicate structure was the dominant factor.

Structural Changes in Metallic Glass-Forming Liquids on Cooling and Subsequent Vitrification in Relationship with Their Properties.

The present review is related to the studies of structural changes observed in metallic glass-forming liquids on cooling and subsequent vitrification in terms of radial distribution function and its analogues. These structural changes are discussed in relationship with liquid’s properties, especially the relaxation time and viscosity. These changes are found to be directly responsible for liquid fragility: deviation of the temperature dependence of viscosity of a supercooled liquid from the Arrhenius equation through modification of the activation energy for viscous flow. Further studies of this phenomenon are necessary to provide direct mathematical correlation between the atomic structure and properties.

Elastic Entropic Forces in Polymer Deformation

The entropic nature of elasticity of long molecular chains and reticulated materials is discussed concerning the analysis of flows of polymer melts and elastomer deformation in the framework of Frenkel–Eyring molecular kinetic theory. Deformation curves are calculated in line with the simple viscoelasticity models where the activation energy of viscous flow depends on the magnitude of elastic entropic forces of the stretched macromolecules. The interconnections between deformation processes and the structure of elastomer networks, as well as their mutual influence on each other, are considered.

Influence of Al2O3 and SiO2 on the structure and viscosity of iron-compound bearing calcium-aluminosilicate slags

The effect of the addition of Al 2 O 3 on the viscosity of the iron-compound bearing CaO-SiO 2 -Al 2 O 3 -MgO slags with different SiO 2 content (= 30, 40, and 50 wt%) was investigated at high temperatures. The addition of Al 2 O 3 increased the viscosity of iron-compound bearing calcium-aluminosilicate melts. The addition of Al 2 O 3 to the slag at low-SiO 2 content (= 30 wt%) increased the fraction of Fe 2+ at a fixed iron content because Fe 3+ cations prefer to exist as tetrahedral unit, i.e., Fe 3+ [IV], in the melt. On the other hand, the addition of Al 2 O 3 to the slag at high-SiO 2 content (= 50 wt%) increased the fraction of Fe 3+ at a fixed iron content due to the preference of octahedrally coordinated Fe 3+ [VI] in the slag. Although the redox equilibrium reaction of iron in the CaO-SiO 2 -Al 2 O 3 -Fe t O-MgO system was strongly affected by the basicity of the melt, the addition of Al 2 O 3 polymerized silicate networks regardless of the SiO 2 content in the slags. The activation energy for the viscous flow of the slags had a linear correlation with the non-bridged oxygen per tetrahedron (NBO/T) in the aluminosilicate network. Therefore, the viscosity of the iron-compound bearing calcium-aluminosilicate melt was determined by the degree of polymerization within the aluminosilicate networks. • Viscosity-structure relationship of iron-compound bearing calcium-aluminosilicate system was experimentally confirmed. • Al2O3 increased melt viscosity due to polymerization reaction and redox equilibria of iron-compound. • Activation energy of viscous flow was dominantly affected by degree of polymerization of slag.

Effect of Pressure on Densification and Microstructure of W-Cr-Y-Zr Alloy during SPS Consolidated at 1000 °C

During the spark plasma sintering (SPS) consolidation process, the pressure affects the densification and microstructure evolution of the sintered body. In this paper, the W-Cr-Y-Zr alloy powder was heated to 1000 °C under different applied pressure conditions using spark plasma sintering process, and the effect of pressure on the densification process and microstructure was analyzed. Due to the low sintering temperature, the crystalline size of all the produced W-Cr-Y-Zr alloy is less than 10 nm, which is close to that of the original powders. Cr-rich phase can be detected in the sintered samples due to spinodal decomposition. It is found in this work that the external pressure will increase the contact area between the powder particles, resulting in a higher local pressure at the particle contact, which promotes densification by sliding between the particles under the condition of softening of the particle surface. Additionally, according to the viscous flow theory, the viscous flow activation energy decreases with the increase of pressure. This is because the pressure provides additional driving force to the powder viscous flow process and accelerates the powder shrinkage.

Effect of temperature and composition on density and dynamic viscosity of (lanthanide metal salts + urea) deep eutectic solvents

• Lanthanide metal-based type IV deep eutectic solvents (DESs) are prepared. • Density of type IV metal DESs are higher compared to the other urea-based DESs. • Dynamic viscosities of these DESs are lower compared to other urea-based DESs. • Viscosity of the DESs exhibits Vogel − Fulcher − Tammann (VFT) temperature dependence. • Density and viscosity both decrease with increase in mole ratio of urea. Deep eutectic solvents (DESs) are rapidly becoming solvent media of prominence due not only to their unique properties but also to their promising environmentally-benign nature. For effective utilization of these neoteric media, assessment of their physical properties is essential. Density and dynamic viscosity of a class of DESs constituted of a hydrated lanthanide salt and urea at varying composition in the temperature range 293.15 to 363.15 K are presented. Specifically, different possible eutectic mixtures of lanthanum nitrate hexahydrate: urea (named La : Urea), cerium nitrate hexahydrate: urea (named Ce : Urea) and gadolinium nitrate hexahydrate: urea (named Gd : Urea) are investigated. DES (Gd : Urea) at 1: 2 mole ratio exhibits the highest density (1.98783 g.cm −3 at 293.15 K) of all the DESs investigated; density is found to decrease with increasing urea. Density of these DESs decreases linearly with increasing temperature. Dynamic viscosity of these DESs also decrease with increasing urea content. The temperature dependence of the dynamic viscosity follows Vogel − Fulcher − Tammann (VFT) expression. While the activation energy of viscous flow ( E a,η ) for these (lanthanide salt : Urea) DESs is closer to those of (choline chloride + H-bond donor) DESs, their viscosity-temperature dependence is similar to that of common imidazolium ionic liquids.

Effect of B<sub>2</sub>O<sub>3</sub> on ESR Slag Viscosity for Remelting 9CrMoCoB Steel

The viscosity of the slag constituted by 55%CaF2–20%CaO–3%MgO–22%Al2O3–x%B2O3 (mass fraction: x ≤ 3) was measured by rotating cylinder method during the electroslag remelting (ESR) of 9CrMoCoB steel to analyze the effects of the B2O3 content on slag viscosity, break point temperature, and activation energy for viscous flow. Meanwhile, the slag’s structural characteristics were studied by Raman spectrometry. Results indicated that when T ≥ 1663 K, the viscosity changed gently with temperature, showing the value of about 0.055 Pa·s, which was rarely affected by w(B2O3). However, with the increase of w(B2O3) in the slag, the Ca3B2O6 with a low melting point was formed, reducing the slag’s break point temperature from 1628 K to 1563 K. According to the NBO/T value and Raman spectra, B2O3, as a network generating oxide, improved the slag’s degree of polymerization, thus strengthening and complicating its network structure at high temperatures. In addition, as the w(B2O3) increased from 0 to 3%, the activation energy for viscous flow rose from 64 kJ·mol−1 to 94 kJ·mol−1 in the slag.