Rheology Control Research Articles

Enhanced Extrusion Processability of PLA Blends through Rheology Control Using Biodegradable PLA-based Graft Polymers

Enhanced Extrusion Processability of PLA Blends through Rheology Control Using Biodegradable PLA-based Graft Polymers

Rheology dependent pore structure optimization of high-performance foam concrete

Foam concrete encounters a fundamental challenge in balancing lightweight and high strength. Pore optimization is the key to address this problem. This study starts with rheology control to optimize the pore structure of foam concretes, thereby designing high-performance foam concrete (HPFC). X-ray computed tomography was employed to explore the relationship between rheology and pore characteristics, revealing the corresponding control mechanisms. The findings indicated that rheological parameters, particularly viscosity, significantly influenced pore size, uniformity, sphericity, fractal dimension and connectivity. Therefore, there was an optimal viscosity range (1.30 ± 0.15 Pa·s) for achieving the desirable pore structure. Mechanical analysis demonstrated that the viscosity could impact the balance of the added foams under dynamic and static conditions via drag force, resulting in changes to the pore structure. After pore optimization, the HPFCs exhibited high compressive strength (2–3 times higher than normal foam concrete at an equal density) and excellent durability comparable to high-performance concrete.

Rheology control of cement paste by in-situ polymerization for 3D printing applications

Rheology control is the most critical determinant of success in 3D concrete printing (3DCP), typically achieved through the hydration control of cement. However, this inevitably leads to overdesign of printed concrete featuring a low water-to-binder ratio (w/b), which is incompatible with its non-load bearing purpose and raises a series of environmental and durability problems, such as high carbon footprint and early-age shrinkage. Herein, we propose a novel rheology control strategy via in-situ polymerization, allowing the mix design of printed concrete with a high w/b ratio of 0.6. The proposed approach consists of two stages: 1) introducing monomers as retarders to extend the open time during pumping, and 2) incorporating initiators into the mixture to trigger polymerization, facilitating the structural build-up after deposition by forming polymer bridges between cement particles. We show that the addition of monomers significantly retards yield stress growth, while the following in-situ polymerization engenders a rapid strength development, satisfying the rheological requirements for 3DCP. Mechanistic experiments reveal that the retarding effect results from the complexation of monomers with aqueous species, such as Ca2+ ions, thereby hindering the nucleation of hydrates. As polymerization initiates, the impetus for the structural build-up of the cement pastes first originates from the proliferation of polymer bridges due to the gradual formation and adsorption of polymer, and then relies on the reinforcement of these polymer bridges through the formation of chemical bonds or crosslinks. On top of the environmental benefit, the proposed strategy holds the potential in avoiding admixtures conflict, mitigating early-age shrinkage, and improving mechanical properties. Our strategy opens possibilities for a novel technical route to achieve rheology control of 3DCP, and the discovery in this work will be a landmark for revealing the mechanism of 3DCP via in-situ polymerization.

Effect of Ionic Liquids with Different Structures on Rheological Properties of Water-Based Drilling Fluids and Mechanism Research at Ultra-High Temperatures.

The rheology control of water-based drilling fluids at ultra-high temperatures has been one of the major challenges in deep or ultra-deep resource exploration. In this paper, the effects of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonimide) (ILA), 1-ethyl-3-methylimidazolium tetrafluoroborate (ILB) and N-methyl, butylpyrrolidinium bis(trifluoromethanesulfonimide) (ILC) on the rheological properties and filtration loss of polymer-based slurries at ultra-high temperatures (200 °C and 240 °C) are investigated by the American Petroleum Institute (API) standards. The results show that ionic liquids with different structures could improve the high-temperature rheological properties of polymer-based drilling fluids. The rheological parameter value (YP/PV) of the polymer-based slurry formulated with ILC is slightly higher than that with ILA at the same concentration, while the YP/PV value of the polymer-based slurry with ILA is slightly higher than that with ILB, which is consistent with the TGA thermal stability of ILA, ILB, and ILC; the thermal stability of ILC with pyrrolidine cations is higher than that of ILA with imidazole cations, and the thermal stability of ILA with bis(trifluorosulfonyl)amide anions is higher than that of ILB with tetrafluoroborate anions. Cation interlayer exchange between organic cation and sodium montmorillonite can improve the rheological properties of water-based drilling fluids. And meantime, the S=O bond in bis(trifluorosulfonyl)amide ions and the hydroxyl group of sodium montmorillonite may form hydrogen bonds, which also may increase the rheological properties of water-based drilling fluids. ILA, ILB, and ILC cannot reduce the filtration loss of polymer-based drilling fluids at ultra-high temperatures.

Variability of lead-zinc sulfide ore slurry rheological properties and its influence on flotation conditions

We investigated how the rheological characteristics of a flotation slurry change in response to variations in mineral species, slurry concentration, and particle size; slurry pH; and trap and rheological control reagent concentrations using slurries containing galena, sphalerite, quartz, and kaolinite. The results indicate that reducing particle size and increasing slurry concentration leads to varying degrees of increase in apparent viscosity and yield stress. At the same particle size, the slurry exhibits the following order of apparent viscosity and yield stress: kaolinite > galena > sphalerite > quartz. In addition, as the slurry’s apparent viscosity and yield stress increase, the rheology decreases, creating progressively unfavorable conditions for the flotation of lead, zinc, and other target minerals. Furthermore, changes in pH have no significant effect on the slurry’s rheology when the slurry is comprised of vein minerals. Moreover, galena and sphalerite depict particle agglomeration in the slurry. Ultimately, the addition of sodium silicate as a rheological control reagent substantially enhances the slurry’s rheological properties. This results in a system where problematic minerals like kaolinite are more effectively dispersed, thereby promoting efficient lead-zinc mineral flotation. Regarding the flotation of lead sulfide and zinc minerals, the addition of kaolinite raises the apparent viscosity of the mixed slurry, hindering the flotation of the target minerals. Conversely, quartz lowers the apparent viscosity aiding the flotation separation process. Understanding the relationship between flotation conditions and the pulp’s rheological properties can provide valuable guidance for subsequent flotation tests.

Exploring the Elemental Interactions of Melamine with Binder–Metal Powder Mixtures: A Pathway to Enhanced Catalytic Debinding and Rheological Control

Exploring the Elemental Interactions of Melamine with Binder–Metal Powder Mixtures: A Pathway to Enhanced Catalytic Debinding and Rheological Control

Graphene - Carbon Quantum Dot Ink Formulation: Porposal & Conceptualization

This proposal presents a novel method to improve the conductivity and adaptability of conductive inks by using graphene and carbon quantum dots. The goal is to generate an ink formulation with improved mechanical flexibility, electrical conductivity, and charge transport by mixing these nanoparticles. Printability, adherence, and conductivity on a range of substrates—including paper, plastics, and textiles—will all be maximized for this formulation. To guarantee stability, rheological control, and compatibility with current printing technology, the ink will go through a thorough evaluation and characterization process. This ground-breaking conductive ink has the potential to transform a number of sectors and advance sustainable technology through its use in flexible electronics, energy storage devices, smart packaging, and other areas.

Rheology control and 3D concrete printing with fly ash-based aqueous nano-silica enhanced alkali-activated binders

Rheology control and 3D concrete printing with fly ash-based aqueous nano-silica enhanced alkali-activated binders

Rheological Properties and Inkjet Printability of a Green Silver-Based Conductive Ink for Wearable Flexible Textile Antennas.

The development of e-textiles necessitates the creation of highly conductive inks that are compatible with precise inkjet printing, which remains a key challenge. This work presents an innovative, syringe-based method to optimize a novel bio-sourced silver ink for inkjet printing on textiles. We investigate the relationships between inks' composition, rheological properties, and printing behavior, ultimately assessing the electrical performance of the fabricated circuits. Using Na-alginate and polyethylene glycol (PEG) as the suspension matrix, we demonstrate their viscosity depends on the component ratios. Rheological control of the silver nanoparticle-laden ink has become paramount for uniform printing on textiles. A specific formulation (3 wt.% AgNPs, 20 wt.% Na-alginate, 40 wt.% PEG, and 40 wt.% solvent) exhibits the optimal rheology, enabling the printing of 0.1 mm thick conductive lines with a low resistivity (8 × 10-3 Ω/cm). Our findings pave the way for designing eco-friendly ink formulations that are suitable for inkjet printing flexible antennas and other electronic circuits onto textiles, opening up exciting possibilities for the next generation of E-textiles.

Rheology control and shrinkage mitigation of 3D printed geopolymer concrete using nanocellulose and magnesium oxide

3D printing concrete (3DPC) is an emerging technology that produces concrete using digital method and has revolutionized the traditional labor-intensive construction mode. However, the free formwork printing and layer-by-layer production of 3DPC induce severe shrinkage and plastic cracking during the early ages, especially for the geopolymer based materials. This research utilizes the nano-fibrillated cellulose (NFC) with the combination of magnesium oxides expansive agent (MEA) to mitigate the plastic and drying shrinkage of 3D printing geopolymer concrete (3DPGC), while optimizing its rheological behavior. The results show that after modification with proper dosages of NFC and MEA, 3DPGC showed reduced plastic and drying shrinkage at early ages, with improved printability, buildability, and mechanical strength. The underlying role of NFC and MEA on the performance of 3DPGC was thoroughly analyzed with rheometry, calorimetry, scanning electron microscopy, and internal humidity test. The water retention ability of nanocellulose can provide more moisture at early ages, thus mitigating cracking, while MEA can compromise the drying shrinkage at later ages. The contribution of the study shed light on the application of nanocellulose and MgO to increase the volume stability and mechanical performance of 3D printing geopolymer concrete.

Effects of mixing conditions and activator anionic species on the rheology of silicate-activated slag concrete

The proper control of the rheological performance of silicate-based alkali-activated slag (AAS) mixtures is problematic, as the conventional superplasticizers become less effective in alkaline media. Nevertheless, several methods have been proposed to improve the workability of silicate-activated AAS, such as by extending the mixing time, and replacing sodium silicate with sodium carbonate activators. However, the underlying fluidizing mechanism is not yet well understood in the literature, which is crucial knowledge to achieve proper rheology control of silicate-activated AAS.In this study, the effects of mixing conditions and activator anionic species on the rheology of silicate-activated AAS concrete have been assessed. The reaction products, particle size and interparticle interactions, as well as the reaction kinetics in AAS, have been further investigated to understand the distinct fluidizing mechanisms. By using a longer mixing time, it was found that the solid particles formed at early ages are broken down into smaller particles, accompanied by a slight increase in the amount of reaction products to improve the fluidity. With the sodium carbonate substitution, the calcium ions dissolved from slag particles are entrapped into calcium carbonate precipitates to slow down the accumulation of C-(A)-S-H phases, leading to a better dynamic flow. However, the interparticle interactions are intensified due to the formation of larger particles and the declined dispersing effect induced by silicate activators.

Vibrorheology of fresh cement-based materials with different compaction energy

Vibration is commonly applied to the placement of cement-based materials to improve their fluidity and compactness. Appropriate compaction could ensure the designed performance by preventing the formation of voids and cavities within a structure. In recent years, the application of vibration has been extended to the rheology control of 3D printable concrete as well. While previous studies have reported on the effective radius of compaction and rheological changes in cement-based materials induced by poker-type vibrators, there has been limited in-depth research on the rheological behavior beyond this effective radius, particularly in relation to the compaction energy. This study investigates the rheological behavior of a cement-based material under controlled vibration energy across a wide range of shear rates. A novel device is proposed for the precise control of compaction energy, in terms of the energy transfer rate per unit volume (power density) of vibration, and the vibrorheology under various power densities is measured. Experimental results reveal that viscosity at a low shear rate decreases proportionally to power density, while vibration has negligible effects on viscosity at a high shear rate. Furthermore, a correlation between power density and normalized yield stress is established, along with the effects of varying water-to-cement ratios. The study also discusses the influence of the vibration frequency on the effective radius of the poker-type vibrator.

Upscaling active rheology control to cement mortar with the intervention of an inline magnetic field

Upscaling the printing ink from cement paste to mortar level is the path people must take to apply active rheology control to smart and advanced digital fabrication, which will decrease the content of binder and reduce carbon footprint. This study investigates the rheological response of cement mortars with carbonyl iron particles (CIPs) by using penetration tests and vane tests. A customized magnetorheological test setup, making use of a pipe/nozzle-like inline magnetic intervention, was developed to modify the rheological properties of responsive mortars within a few seconds. The alignment of magneto-responsive particles and the hindrance of sand on magneto-responsive particles in the mortars were visualized and determined by scanning electron microscopy (SEM). With an inline magnetic field, the yield stress determined by the slow penetration test and the torque measured by the vane test increased by a significant factor. The magneto-responsive effect and the response speed rate of the mortar can be adjusted on demand and in time. The effect of cement-to-sand (c/s) ratios and sand gradations on the magnetorheological response of cement mortars was studied. With the increase of sand content (decrease of c/s ratio), the percent increase of yield stress and torque decreased and the magneto-response speed reduced, which indicates a reduction in response efficiency. The magneto-responsive particles could more easily move in the mortar when the particle size of sand increased. Experimental proofs of concept to apply active rheology control to a 3D printing nozzle or pumping line were conducted.

Investigation of TPEG comb polymer as filtration and rheological additives for high-temperature water-based drilling fluid

During oil and gas drilling, high-temperature and high-salt considerably deteriorate the rheological and filtration properties of drilling fluid. In this study, two novel comb polymers P-TPEG-10 and P-TPEG-24, with different side chain lengths, were synthesised as filtration and rheological additives for drilling fluids under high-temperature and high-salt environments. When 2 wt% isopentenyl polyoxyethylene ether (TPEG) comb polymer was added to bentonite water-based drilling fluid (BT-WBDF), the viscosity and yield point of the drilling fluid were considerably improved, the filtration loss was considerably reduced before and after hot rolling at 220 ℃ and BT-WBDF could resist 15 wt% NaCl or 0.5 wt% CaCl2. P-TPEG-10 has a better viscosity-increasing effect than P-TPEG-24, and P-TPEG-24 has a better filtration control effect than P-TPEG-10. The excellent rheological and filtration control effects are attributed to the spatial network structure formed by the comb polymer and bentonite particles. Strong hydration groups such as sulfonic groups on the main chain and the intercalation of polyethylene glycol (PEG) side chains increases the thickness of the diffusion double electric layer of bentonite particles and inhibit the aggregation of BT particles. BT-WBDF maintains a reasonable particle size distribution, thus forming a thin and dense filter cake, and effectively reducing the filtration volume. It is expected to play an essential role in the filtration and rheological control of high temperature drilling fluid.

A potential active rheology control approach for 3D printable cement-based materials: Coupling of temperature and viscosity modifiers

Recently, the active rheology control for 3D printable cement-based materials (3DPCM) has gained increasing attention due to the challenging rheological requirements during printing. Inspired by the influences of polymers on the temperature sensitivity of rheological properties, here we propose a concept of active rheology control for 3DPCM coupling temperature control with the utilization of viscosity modifiers. Firstly, the rheological properties associated with 3D printing in response to a temperature range from 5 °C to 45 °C were investigated through flow curve, stress growth and small-amplitude oscillatory shear tests. Subsequently, total organic carbon and isothermal calorimetry tests were performed to further analyze the mechanism. Finally, validation 3D printing tests were conducted. Results indicate that increasing temperature improves the efficacy of hydroxypropyl methylcellulose and polycarboxylate ether-based superplasticizer through accelerated dissolution and adsorption, and enhanced chain stretching, thus allowing for an intensified or a suppressed response to temperature in the apparent viscosity, thixotropic area, static yield stress and storage modulus of 3DPCM. Increasing temperature also compensates for the delay in cement hydration due to the addition of polymers. Printing experiments provide preliminary evidence of the feasibility of active rheology control for 3DPCM through coupling between temperature and viscosity modifiers to improve the printability. The thickness ratio and width ratio of top layers to bottom layers of 3DPCM with HPMC were 1.46 and 0.84 when printed at 25 °C, which are 14.1% lower and 58.3% higher compared to that printed at 15 °C.

Crucial role of water-present melting in metagranite: Implications for the instigation of crustal-scale shear zones

Abstract Where, when, and why large-scale shear zones nucleate and propagate into the continental lithosphere are critical issues that challenge the research in tectonics. The East Variscan shear zone is one of the crustal-scale strike-slip faults that shaped the Variscan orogenic crust during late Carboniferous time. Field-based structural analysis and petrological observations demonstrate that suprasolidus high-strain deformation zones and metagranite occurrences are spatially correlated. Among the three dominant lithologies forming this orogenic middle crust (metapelite, metagraywacke, and metagranite), petrological observations and phase equilibrium modeling indicate that the latter is the first lithology that melts during collision-induced heating, in response to H2O-fluid-saturated melting. Our field data and modeling suggest that the water-fluxed melting of metagranite has a primary rheological control on the localization, instigation, and growth of crustal-scale shear zones in the middle crust. Thus, the distribution and geometry of metagranite at the crustal scale could be regarded as critical parameters influencing the rheological inheritance governing the tectonic evolution and localization of bulk strain in the continental lithosphere.

Research and application of low oil-water ratio organoclay-free oil-based drilling fluid technology

This paper introduces the formation and application of a low oil-water ratio organoclay-free oil-based drilling fluid. Shale oil and gas are important alternative energy sources. Due to the extremely complex geological conditions, oil-based drilling fluid technology is commonly used to reduce complexity. Although some achievements have been made, there are still problems such as unstable wellbore, difficult rheological control, and high cost. A stable and low-viscosity water-in-oil emulsion system was successfully prepared by using optimized fatty acid imidazolines emulsifier and alkyl alcohol ether wetting agent, which enabled the oil-based drilling fluid to have a larger solid and water phase capacity. On this basis, a special poly-fatty acid amide rheological modifier was used to assist in the regulation of rheological parameters, resulting in a low-viscosity and high-shear structure of the oil-based drilling fluid. This effectively ensured the efficiency of cuttings carrying while reducing the adverse effects of viscosity on Equivalent Circulating Density(ECD). The low oil-water ratio oil-based drilling fluid technology has been applied in a shale gas drilling platform in southern Sichuan, China, which greatly reduces the cost of oil-based drilling fluid while ensuring drilling efficiency.

Thermo-responsive polymer-based Janus biogenic-nanosilica composite, part B: Experimental study as a multi-functional synergistic shale stabilizer for water-based drilling fluids

Wellbore instability caused by shale swelling and dispersion has always been a thorny issue for drilling complex formations. Nanotechnology has offered a revolutionary solution for shale stabilization in water-based drilling fluids (WBDFs). Recent technological advancement in nanomaterials for optimal performance using economically and environmentally sustainable pathway is an utmost desire in oil and gas industries. In this research, Janus nanocomposite (TRJN) with rice husk (RH)-extracted biogenic nanosilica core (RH-NSP) having the shell integrating synergistic benefits of thermo-responsive and amino-based materials, which was reported in our previous work was assessed as a novel shale stabilizer in drilling fluids. The product is anticipated to simultaneously improve the chemical inhibition and nanoplugging performances in shaly formations. TRJN was assessed as an additive in WBDF in comparison with symmetrical thermo-responsive polymer-based nanocomposite (TRN) counterpart and parent RH-NSP. Results from the rheological test revealed that, albeit both nanocomposites (i.e., TRN and TRJN) could provide a certain rheological control above the LCST compared to RH-NSP, but TRJN-blended fluid was less sensitive to increasing temperatures. The inhibitory effects were investigated based on cuttings hot rolling recovery rate, linear swelling rate, pressure penetration rate, tensile strength of shale reduction rate, and high temperatures and high pressures filtration loss. TRJN demonstrated higher chemical inhibition compared to RH-NSP and TRN, driving a better capacity to control pressure penetration. The higher mean free energy of TRJN/Na-Mt (sodium montmorillonite) system than TRN/Na-Mt system was an indication of its stronger interactions with Na-Mt particle, which triggered changes in microstructures, considering the results of zeta potential, FT-IR, surface wettability, X-ray diffraction, and SEM analyses. This, therefore contributing to firmly trap the TRJN into the multi-scale pore structure of the shale and beneficially promoted the construction of a tight hydrophobic plugging layer over the shale surface from the outward face. Lastly, the synergistic enhancement mechanisms of shale inhibition with TRJN was further proposed.

Rheology of dense suspensions of ideally conductive particles in an electric field

The rheological behaviour of dense suspensions of ideally conductive particles in the presence of both electric field and shear flow is studied using large-scale numerical simulations. Under the action of an electric field, these particles are known to undergo dipolophoresis (DIP), which is the combination of two nonlinear electrokinetic phenomena: induced-charge electrophoresis (ICEP) and dielectrophoresis (DEP). For ideally conductive particles, ICEP is predominant over DEP, resulting in transient pairing dynamics. The shear viscosity and first and second normal stress differences $N_1$ and $N_2$ of such suspensions are examined over a range of volume fractions $15\,\% \leq \phi \leq 50\,\%$ as a function of Mason number $Mn$ , which measures the relative importance of viscous shear stress over electrokinetic-driven stress. For $Mn < 1$ or low shear rates, the DIP is shown to dominate the dynamics, resulting in a relatively low-viscosity state. The positive $N_1$ and negative $N_2$ are observed at $\phi < 30\,\%$ , which is similar to Brownian suspensions, while their signs are reversed at $\phi \ge 30\,\%$ . For $Mn \ge 1$ , the shear thickening starts to arise at $\phi \ge 30\,\%$ , and an almost five-fold increase in viscosity occurs at $\phi = 50\,\%$ . Both $N_1$ and $N_2$ are negative for $Mn \gg 1$ at all volume fractions considered. We illuminate the transition in rheological behaviours from DIP to shear dominance around $Mn = 1$ in connection to suspension microstructure and dynamics. Lastly, our findings reveal the potential use of nonlinear electrokinetics as a means of active rheology control for such suspensions.

A comparison of magneto-responsive particles and testing protocols for active rheology control of cementitious materials

Magneto-responsive cementitious materials with magnetic interventions enable on-demand and real-time adjustment of rheology. This research aims to elaborate the early-stage magneto response of cement pastes using different types of Fe3O4 particles and carbonyl iron particles. A series of methods to evaluate the magnetorheological response of cementitious materials were established. The magneto-responsive cement pastes were tested by shear test and small amplitude oscillatory shear test at constant and time-varying magnetic fields. The increase of static yield stress and storage modulus after applying a magnetic field was a time-dependent process, while the decrease of static yield stress and storage modulus was an instant process at the moment of removing magnetic fields. Such a procedure can be reversibly controlled in real time. The cement pastes containing different magneto-responsive particles showed significant difference in the onset of flow and structural build-up. With the intervention of a magnetic field, the static yield stress and storage modulus of mixtures with carbonyl iron particles were able to increase with one order of magnitude. Compared with the particle size distribution and particle morphology, the magnetic parameters of magneto-responsive particles dominated the magnetorheological properties of cementitious materials. Shear tests were found the most effective to evaluate the magneto response of cement pastes with the intervention of a magnetic field.