Molten Viscosity Research Articles

Unraveling chemical and rheological mechanisms of self-healing with EMAA thermoplastics in fiber-reinforced epoxy composites

Interlaminar delamination is a prevalent and insidious damage mode limiting the mechanical integrity and lifetime of fiber-reinforced composites. Conventional resolution involves over-design, laborious inspection, and repair/replacement at cost to the economy and environment. Self-healing via in situ thermal remending of thermoplastic interlayers offers a promising solution. However, better understanding of the healing agent and related mechanisms is necessary to tailor healing performance. Here, we compare non-neutralized (copolymer) and metallic-ion neutralized (ionomer) poly(ethylene-co-methacrylic acid) (EMAA) thermoplastics for healing interlaminar fracture. We reveal (i) how EMAA chemistry affects the interfacial reactions driving healing and (ii) the influence of molten viscosity on repair efficiency. At fixed viscosity, higher methacrylic acid content, chain mobility, and lower neutralization positively influence healing, where lower melt viscosity at fixed temperature improves delamination recovery. Thus, this study deepens scientific understanding of key variables for healing interlaminar fracture with EMAA, providing new insight for the design of multifunctional composites.

Density, Surface Tension, and Viscosity of Molten Ni‐Based Superalloys Using the Maximum Bubble Pressure and Oscillating Crucible Methods

Accurate data on the high‐temperature thermophysical properties, which are density, surface tension, and viscosity, are indispensable for performing high‐precision casting simulations of Ni‐based superalloys. Viscosity is the most important thermophysical property for thermofluidic analysis. However, measuring the viscosity of an alloy, which is lower than that of molten glass, is difficult, and experimental viscosity data are limited. Herein, the density of Ni‐based superalloys is measured using the maximum bubble pressure (MBP) method to determine viscosity. The viscosity is evaluated using the oscillating crucible method. The surface tension is simultaneously measured using the MBP method. In these results, the average density values [kg m−3] of Alloy 65, Alloy 718, Alloy WA, and Alloy 720 are 7.52 × 103, 7.43 × 103, 7.82 × 103, and 7.52 × 103, respectively. The average surface tension values [N m−1] of Alloy 65, Alloy 718, Alloy WA, and Alloy 720 are 1.55, 1.54, 1.47, and 1.51, respectively. The fitting equations of the molten Ni‐based superalloys are as follows. 1) Alloy 65: ; 2) Alloy WA: ; 3) Alloy 720: ; 4) Alloy 718: .

Roasting mechanism of lightweight low-aluminum–silicon ceramisite derived from municipal solid waste incineration fly ash and electrolytic manganese residue

Municipal solid waste incineration (MSWI) fly ash and electrolytic manganese residue (EMR) belong to hazardous waste, and must be disposed of before processing. It was found that the low content of silicon and aluminum at low roasting temperature can meet the expansion mechanism of lightweight aggregates. A low-aluminum–silicon lightweight ceramisite was successfully prepared from MSWI fly and EMR, the formation mechanism of which was that the viscosity of molten stuffs in pellet was the function of temperature and chemical composition and had enough capacity of capturing the emerged gas over roasting. The resulting ceramisite met with the requirement of Lytag commercial lightweight aggregate. The content of heavy metal in ceramisite accorded with the requirement of soil environmental quality for development GB 36600–2018 Class I, and PCDD/Fs in ceramisite was 2.0 ng I-TEQ/kg, which was safe. The collaboration of thermal simulation and characterization (SEM-EDS, FTIR and XRD) elaborated the formation mechanism of ceramisite, with six stages provided.

Molecular Dynamics Study on the Effect of SiO2/Al2O3 Mass Ratio on the Structural Properties and Viscosity of Molten Fused Red Mud

In this study, molecular dynamics simulation was used to study the effect of SiO2/Al2O3 mass ratio on the structural properties and viscosity of molten fused red mud. The stability of various T–O bonds in the melt was elucidated by analyzing the bond angle and coordination number; the degree of polymerization, and the stability of the melt were explored by analyzing the number of T–O–T bridging oxygen (BO) and the distribution of QSin and QAln of [SiO4]4− as well as that of QSin and QAln of [AlO4]5−; the self-diffusion coefficient of each atom was determined by mean square displacement (MSD) analysis; and the trend of the melt viscosity was analyzed according to the relationship between diffusion and viscosity. The results show that as the ratio of SiO2/Al2O3 increases, the viscosity of molten fused red mud first increases, then decreases, and finally increases. This is because Ti4 and Fe3+ combine with O2− to form [TiO6]8− octahedron and [FeO4]5− tetrahedra, which increase the degree of depolymerization of the melt.

Thermophysical modeling of raw glaze liquidus temperature and viscosity

AbstractRaw glazes, which do not contain pre‐melted glass frits, are widely used due to their low cost. The natural variability of the mineral compositions used in raw glazes affects their viscosity during firing. Molten glaze viscosity plays an important role in determining the final surface quality; therefore, it is important to determine how raw glaze composition and firing conditions affect viscosity. Thermophysical modeling provides a way to evaluate the liquidus temperature and viscosity of molten glazes as a function of composition and oxygen activity. Equilibrium phase volume fraction and composition of 242 raw glaze recipes were evaluated under oxidizing and reducing conditions. Undissolved or precipitation of solid phases explains the secondary flux transition from anti‐fluxing to fluxing near the liquidus temperature. The liquidus temperature and viscosity of iron glazes decrease as a function of increasing iron content under a reducing atmosphere. The empirical probability distribution of molten glaze viscosity follows a lognormal distribution, with lead glazes having significantly lower viscosity compared with glazes without lead. The peak firing temperature viscosity of lead‐free glazes is near the working point of glass. Multiple linear regression analysis shows that the peak firing temperature viscosity and liquidus temperature significantly predict the viscosity factor.

Simulation of printer nozzle for 3D printing TNT/HMX based melt-cast explosive

Fused deposition modeling (FDM) as one of the additive manufacturing (AM) technologies has been widely used in various manufacturing industries to fabricate products with complex structures; however, the application of FDM in energetic materials (EMs) was still less common. In this work, the effect of HMX solid content and particle size on the viscosity of molten TNT/HMX explosives were investigated. Then, the computational fluid dynamics (CFD) and discrete element method (DEM) were used to simulate the influence of viscosity, pressure, temperature, nozzle diameter, and particles on the fluid flow inside the 3D printer nozzle. In addition, an FDM 3D printer was used to prepare TNT/HMX-based explosives, and various characterization methods were applied to explore the structure and morphology of printed samples. This work provided guidelines for FDM technology to fabricate EMs and proved that FDM was more suitable than the conventional melt-casting method to prepare explosives with high viscosity and special-shaped structures.

Influence of API physico-chemical properties on amorphization capacity of several mesoporous silica loading methods

The objective of this work was to evaluate the impact of physico-chemical properties of pharmaceutical drugs on the optimal mesoporous silica loading methods. Indeed, a good combination between drug and loading process has to be studied to promote the deepest penetration of the drug inside the mesopores, allowing high drug amorphization. Six molecules, namely lidocaine and its hydrochloride, ibuprofen, ketoprofen, artemether and miconazole, with different physico-chemical properties (the ionized character, the acid-base character, the HBDA number, the solubility in sc-CO2 and the behavior under subcritical CO2) were used to produce drug-silica formulations. Different impregnation processes (physical mixing, melting, wetting, sc-CO2 and subcritical CO2 impregnations) have been compared for each drug, in terms of drug recovery and crystallinity. Formulations showed drug percentage close to 100% except for supercritical soluble drug formulations impregnated by using sc-CO2. However, the basic drug character provided less or no drug loss during impregnation. Processing insoluble sc-CO2 molecule under supercritical conditions led to less crystallinity than the correspondent physical mixture suggesting an interesting repulsive effect that forces the drug penetration within the mesopores. Besides, it has been also highlighted that the HBDA number is not sufficient to predict the final drug loading. Melting methods have high interest considering the drugs tested and subcritical CO2 could increase the loading, especially for drugs with high molten viscosity. This study showed that a plethora of loading methods can be used to provide high drug loaded MS formulations with a wide choice of equipment.

Smart TPE Materials Based on Recycled Rubber Shred.

Thermo-responsive shape memory materials were developed based on recycled ethylene-propylene-diene (EPDM) rubber shred and thermoplastic elastomers (TPE). Ethylene-1-octene TPEs (Engage 8180, 8411, 8452) with varying degrees of crystallinity and Mooney viscosity were used to prepare the composite materials. To avoid the deterioration of static mechanical properties after mixing recycled EPDM rubber shred (RS) with thermoplastic elastomers, they were partially cured using dicumyl peroxide. The peroxide curing was the most effective for a rubber shred/Engage 8180 blend, where the highest cure rate index (CRI), 1.88 dNm⋅min−1, was observed. The curing caused an approximately 4-fold increase of tensile strength (TS) values for EPDM rubber shred/thermoplastic elastomer blend to the level acceptable for the rubber industry compared with an uncured blend. The incorporation of EPDM rubber shred changed thermoplastic elastomers’ viscoelastic behavior, increasing the values of storage (G′) and loss (G″) modulus. The lowest viscosity of molten Engage 8411 during mixing led to higher compatibility of rubber shred RS/8411 blend, as confirmed by analysis of Cole-Cole plots and the blend morphology. All rubber shred RS/TPE blends showed the shape memory behavior. For the RS/Engage 8452 blend, the highest shape fixity (F) value (94%) was observed, while the shape recovery (RR) was 87%. Studies confirmed that the intelligent materials with shape memory effect could be obtained via selectively chosen thermoplastic elastomers; ethylene-1-octene as a binder for recycled EPDM. Prepared recycled TPE/rubber shred blends can be successfully reused due to their viscoelastic and mechanical properties. Therefore, such a concept can be potentially interesting for the rubber industry.

Structure and viscosity of CaO–Al2O3–B2O3–BaO slags with varying mass ratio of BaO to CaO

AbstractThe structure of CaO–Al2O3–B2O3–BaO glassy slags with varying mass ratio of BaO to CaO has been investigated by Raman spectroscopy, 11B and 27Al magic angle spinning nuclear magnetic resonance (MAS‐NMR) spectroscopy and atomic pair distribution function (PDF). 11B MAS‐NMR spectra reveal the dominant coordination of boron as trigonal. Both simulations on 11B MAS‐NMR spectra and Raman spectroscopy indicate the presence of orthoborate as the primary borate group with a few borate groups with one bridging oxygen and minor four‐coordinated boron sites. 27Al MAS‐NMR and PDF show the Al coordination as tetrahedral. Raman spectral study shows that the transverse vibration of AlIV–O–AlIV and AlIV–O–BIII, stretching vibration of aluminate structural units and vibration of orthoborate and pyroborate structural groups. A broader distribution of Al–O bond lengths in PDF also supports the enhanced network connectivity. Viscosity measurements show the increase in viscosity of molten slags with increasing mass ratio of BaO to CaO, which further attributes to the enhanced degree of polymerization of the aluminate network.

Viscosities of Molten B4C-Stainless Steel Alloys

• Viscosities were measured by the oscillating crucible method. • Viscosities of the molten B 4 C-SS alloys increased with B 4 C concentration. • The equation of viscosity of molten B 4 C-SS alloys was determined. • The results will be useful for predicting the viscosities of control rod melts. Determining high precision viscosities of molten B 4 C-stainless steel (B 4 C-SS) alloys is essential for the core disruptive accident analyses of sodium-cooled fast reactors and for analysis of severe accidents in boiling water reactors (BWR) as appeared in Fukushima Daiichi. However, there are no data on the high precision viscosities of molten B 4 C-SS alloys due to experimental difficulties. In this study, the viscosities of molten B 4 C-SS mixtures with 2.5, 5.0, and 7.0 mass% B 4 C were measured using the oscillating crucible method in temperature ranges of 1693–1793 K, 1613–1793 K, 1613–1793 K, and 1713–1793 K, respectively. The viscosity was observed to increase as the B 4 C concentration increased from 0 to 7.0 mass%. Using the experimental data of the molten B 4 C-SS mixtures with 2.5, 5.0, and 7.0 mass% B 4 C in the temperature range of 1713–1793 K, the equation for the viscosity of molten B 4 C-SS alloys was determined, and the measurement error of the viscosity of molten SS+B 4 C alloys is less than ±8%.

Representation of the Multiphysical Properties of SiO2-Al2O3-CaO Slags by Deep Neural Networks

The hybrid analytics and modelling tool is one of the key techniques for the digital twin of industrial processes. Attempt for hybridization of the thermochemical and thermophysical properties of molten SiO2-Al2O3-CaO slags has been recently made at SINTEF Industry. The power of the deep neural networks for the multiphysical modelling of ferroalloy production will be demonstrated in the paper. A deep neural network has been set up for representing thermophysical (electronic conductivity, liquidus temperature, viscosity as well as density) and thermochemical (slag-metal equilibrium composition) properties of the SiO2-Al2O3-CaO system. The physics-based models were first used to model the density, conductivity and viscosity of molten SiO2-Al2O3-CaO slags. Liquidus temperature and metal-slag equilibrium data were calculated using the well-known thermochemical software package, FactSage. These physical models can be used as high-throughput calculation tools for the generation of industrial important labelled data. The DNN model can represent the above labelled metadata with a set of optimized parameters. The DNN model developed in the present study consists of 4 input variables (composition and temperature), 1 hidden layer and 5 output properties was used. The DNN model calculation can almost entirely reproduce all above properties using about 120 parameters. Furthermore, the DNN model can be automatically updated by continuously feeding the experimental data from the laboratory and industry (machine learning). This provides a sound basis for the development of the localized HAM tool for individual ferroalloy producers.

An Investigation on the Relationship between Structure and Viscosity of Silicate Slags

The viscosity of molten slags pivotally influences high-temperature metallurgical processes in industrial operations. This important physical property at a given temperature depends upon the slag structure. In this work, the relationship between structure and viscosity of molten slags is investigated. To this end, the typical experimental techniques for viscosity measurement aresummarized, namely capillary method, falling-body method, rotating method, and oscillating method. We also present viscosity models that have been developed to predict slag viscosities. Raman spectroscopy is a powerful method to determine features of amorphous materials, including the types of atomic bond vibrations and their relative distribution. A group of synthetic slags in the SiO2-CaO-Al2O3 ternary system is considered with compositions close to industrial slags in silicon production. The Raman spectroscopy data is obtained within the wavenumbers on the order of 200–1300 cm−1. The Raman data provides access to the structural information (i.e., the depolymerization of melts), which is linked to viscosity. In order to discuss the relationship between structure and viscosity results for this group of slags, the viscosity values are adopted from the literature. The viscosity is found to be inversely proportional to temperature and the addition of basic oxides, due to the breaking of the silicate network.

Experimental Investigation of ABS Matrix and Cellulose Fiber Reinforced Polymer Composite Materials

ABSTRACT The present study explores the effect of cellulose fiber-reinforced Acrylonitrile-Butadiene-Styrene (ABS) matrix composites on their mechanical, thermal, and impact properties, produced by using different weight percentage. The ABS matrix materials are high molten viscosity, causing less resin flow. Cellulose fiber reinforcement has a good reinforcing filler with an excellent aspect ratio and it renders ultimate mechanical properties generated by hydrogen bonding with high crystallinity. The results exposed the higher tensile strength, thermal and heat deflection temperature by ABS matrix and cellulose reinforced composites than those by using conventionally fabricated Cellulose fiber and ABS matrix composite materials. It is noted that the weight percentage of 20% of cellulose fiber and 80% of ABS polymer composite materials could produce the maximum mechanical and thermal properties of Cellulose fiber and ABS composites, compared to 100% ABS material. Compared to the base matrix ABS, the composite materials increased the tensile strength by 37%. The morphological examination was performed by Field Emission Scanning Electron Microscopy (FESEM) and the results showed the appearance of Cellulose fiber and ABS composites in the fractured tensile specimen.

Structure and Viscosity of Molten CaO-SiO2-FexO Slag During the Early Period of Basic Oxygen Steelmaking

According to the composition variation during the initial period of basic oxygen steelmaking, ice-quenched samples of the CaO-SiO2-FexO system were prepared, and the viscosity and structure of molten slag were further analyzed by a rotary viscometer and Raman spectroscopy, respectively. The results showed that Si4+ existed as Q0, Q1, Q2 and Q3 units. The O2− ions led to the depolymerization of [SiO4] tetrahedrons from Q3 to Q0 units with increasing Ca/Fe ratio. For Fe3+ cations, two types of [FeO4] tetrahedron and [FeO6] octahedron coexisted in the molten slag, and coordination of Fe3+ transformed from tetrahedron to octahedron with the Ca/Fe ratio increasing to 3.18. Viscosity of molten slag showed a continuous decrease because of the simpler network. Moreover, to clarify the viscosity-structure relationship, the viscosity estimation equation applied to the CaO-SiO2-FexO-based system was established in terms of the deconvolution result of the melt structure.

Reference Correlations for the Viscosity of Molten LiF-NaF-KF, LiF-BeF2, and Li2CO3-Na2CO3-K2CO3

In 1974, reference correlations for the viscosity of molten LiF-NaF-KF, LiF-BeF2, and Li2CO3-Na2CO3-K2CO3 were proposed by Janz and have been extensively used since then. However, in the last 45 years, many additional measurements have been published. This is why in this paper, new reference correlations for the viscosity of these salts are proposed. All available experimental data for the viscosity of these three molten salts have been critically examined with the intention of establishing improved or new reference viscosity correlations. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The reference correlation proposed for LiF-NaF-KF, with an uncertainty of 2.9% at the 95% confidence level, expands the temperature range of the previous correlation from (770–970) K to (732–1163) K and retains its uncertainty. The correlation proposed for LiF-BeF2, with an uncertainty of 4.9% at the 95% confidence level, expands the high temperature range of the previous correlation from (740–870) K to (793–1573) K, with a slight loss in its uncertainty. It is, however, a much better correlation as it is based upon measurements not available at the time of the previous one. Finally, the reference correlation for Li2CO3-Na2CO3-K2CO3, with an uncertainty of 3%, also expands the temperature range of the previous correlation from (920–1170) K to (738–1170) K and retains its uncertainty.

Improving Physical Properties of Wax-Based Fuels and Its Effect on Regression Rate

Wax is a brittle thermoplastic material, and its physical properties must be improved so that it can be used as fuel in hybrid rockets. In this study, we use microcrystalline wax and paraffin wax by mixing ethylene vinyl acetate copolymer (EVA) and stearic acid; conduct tensile tests and firing tests; and measure viscosities to obtain the effect of improvement in physical properties on the regression rate. According to the results, microcrystalline wax has higher strength than paraffin wax, and the tensile strength increases as the EVA and the stearic acid contents increase. By contrast, mixing EVA with wax decreases the regression rate, but mixing stearic acid hardly affects the regression rate. The regression rates of these wax-based fuels increase almost proportionally with power of the coefficient of the viscosity of molten fuel at a constant temperature, which agrees with the results of the theoretical analysis.

The MgCO3-CaCO3-Li2CO3-Na2CO3-K2CO3 melts: Thermodynamics and transport properties by atomistic simulations.

Atomistic simulations provide a meaningful way to determine the physicochemical properties of liquids in a consistent theoretical framework. This approach takes on a particular usefulness for the study of molten carbonates, in a context where thermodynamic and transport data are crucially needed over a large domain of temperatures and pressures (to ascertain the role of these melts in geochemical processes) but are very scarce in the literature, especially for the calcomagnesian compositions prevailing in the Earth's mantle. Following our work on Li2CO3-Na2CO3-K2CO3 melts, we extend our force field to incorporate Ca and Mg components. The empirical interaction potentials are benchmarked on the density data available in the experimental literature [for the crystals and the K2Ca(CO3)2 melt] and on the liquid structure issued from ab initio molecular dynamics simulations. Molecular dynamics simulations are then performed to study the thermodynamics, the microscopic structure, the diffusion coefficients, the electrical conductivity, and the viscosity of molten Ca,Mg-bearing carbonates up to 2073 K and 15 GPa. Additionally, the equation of state of a Na-Ca-K mixture representative of the lavas emitted at Ol Doinyo Lengai (Tanzania) is evaluated. The overall agreement between the MD results and the existing experimental data is very satisfactory and provides evidence for the ability of the force field to accurately model any MgCO3-CaCO3-Li2CO3-Na2CO3-K2CO3 melt over a large T-P range. Moreover, it is the first report of a force field allowing us to study the transport properties of molten magnesite (MgCO3) and molten dolomite [CaMg(CO3)2].

Physicochemical Properties of the Molten Iron-Rich Slags Related to the Copper Recovery

The properties of a molten slag play an important role in the separation of the slag from the matte during copper smelting. In this study, the viscosity, electrical conductivity, density, and surface tension of molten FeOt-SiO2-CaO-based slags were measured, and the effects of the common constituents, such as CaO, Fe3O4, and Cu2O, on various properties were investigated. The primary phases in the molten slags which are suitable for the copper recovery process were obtained, and they mainly correspond to fayalite and tridymite. The comparison of the static settling properties of molten industrial copper slag before and after modification is also discussed.

Substitutional effect of Na2O with K2O on the viscosity and structure of CaO‐SiO2‐CaF2‐based mold flux systems

AbstractThe effect of the substitution of Na2O with K2O on the viscosity and structure of molten CaO‐SiO2‐CaF2‐based mold fluxes containing alkali‐oxides at high temperatures has been studied. The CaO/SiO2 mass ratio (C/S) and CaF2 were fixed at 0.8 and 10 mass pct., respectively. The total alkali‐oxide was fixed at 20 mass pct. By systematically substituting the Na2O with K2O, the K2O/(Na2O + K2O) mass ratio was modified between 0.0 and 1.0. Using the rotating spindle method to measure the viscosity at high temperatures, the viscosity was found to increase with higher K2O/(Na2O + K2O). From the slope of the temperature dependence of the viscosity, an apparent activation energy was calculated and increased with higher K2O/(Na2O + K2O), from 96 to 154 kJ/mol, due to the cation size effect on the resistance to shearing. Using Raman spectroscopy of as‐quenched fluxes, the mole fraction of Q3 was found to increase, while the mole fractions of Q2 and Q0 decreased with higher K2O/(Na2O + K2O). The nonbridged oxygen per silicon cation (NBO/Si) decreased from 1.97 to 1.58 with increasing K2O/(Na2O + K2O), suggesting greater complexity of the flux structure with higher K2O/(Na2O + K2O), resulting in a higher viscosity.

Asymmetric bismaleimide-based high-performance resins with improved processability and high Tg over 400 °C

Asymmetric 2-(4′-maleimido)phenyl-2-(4′-maleimidophenoxyl)phenylbutane (EBA-BMI) was successfully mixed with N, N′-(4,4′-diphenylmethane)bismaleimide (DDM-BMI) to prepare the matrix resins for high-temperature fiber-reinforced polymeric composites (glass transition temperature ( Tg) > 400°C). Experimental results imply that DDM-BMI/EBA-BMI (DE-BMIs) show excellent melting performance with wide processing temperature window and low molten viscosity, suggesting excellent compatibility between DDM-BMI and EBA-BMI. For example, the viscosity of DE-BMI41 (DDM-BMI/EBA-BMI, 4/1) is about 474–51 mPa·s in the temperature range of 148–180 °C. In addition, cured DE-BMIs represent remarkable thermal properties with Tg over 400°C, under which the storage modulus could still reach as high as 3.2 GPa. Meanwhile, the coefficient of thermal expansion of these cured resins is about 36–40 ppm °C−1 at 50–250°C, and the 5% weight loss temperature is about 470°C.