Rheological Curves Research Articles

Tailoring Wetting Ridge Dynamics on Hybrid Acrylic Polymers: The Impact of Mechanical Properties on Continuous Wetting.

This study examined the relationships among the wetting speed, the polymer mechanical properties, and the resulting deformation characteristics of various graft copolymers synthesized from acrylic monomers and acrylated l-lactide and ε-caprolactone macromonomers (MMs). The mechanical properties of the polymer films were manipulated with minimal impact on their static contact angles with water by varying their MM composition. The focus was on wetting speeds prior to the onset of stick-slip behavior, where ridges were smoothly pulled over the surfaces, thereby producing a transient deformation indicative of a wave pulse. The height of the propagated ridge structures quickly converged to a steady-state value, depending on the wetting speed and polymer properties, regardless of the initial size. The results show that the propagated ridge height correlates with the wetting speed, and the data are well fitted by the Kelvin-Voigt model, which yields two key parameters: the maximum ridge height at the limit of zero velocity and the characteristic wetting speed. Both parameters correlated linearly with the lactide content in the MMs, and the characteristic wetting speed correlated linearly with crossover frequencies from the rheological master curves of the polymers. Furthermore, the characteristic wetting speed was correlated with the peel force required to remove polymer films from the steel plates, establishing a connection between dynamic wetting and adhesive behavior. Our findings shed light on the interdependence between the material composition, mechanical properties, and wetting behavior. The insights presented offer significant potential for designing materials with controlled wetting properties, particularly for applications where capillary flow and surface interactions play critical roles.

Anti-dispersion, rheological, and mechanical properties of GBFS/FA geopolymer for underwater engineering applications

Cementitious materials used in underwater engineering primarily face challenges such as water infiltration, chloride ion penetration, and sulfate attack. Therefore, the use of fast curing, strong corrosion resistance, and high-performance geopolymers is critical in underwater engineering. In this study, NaOH was selected as the activator, with granulated blast furnace slag (GBFS) and fly ash (FA) serving as precursors. The effects of hydroxypropyl methylcellulose (HPMC) content, alkali content, and the GBFS/FA ratio on the anti-dispersion, rheological, and mechanical properties of the geopolymers were systematically investigated. The results indicated that when the Na₂O content was below 5 wt%, increasing the HPMC enhanced the anti-dispersion properties of the geopolymer paste. However, in a highly alkaline environment (Na2O≥7 wt%), HPMC did not enhance the anti-dispersion properties of the paste. Infrared spectrum analysis suggested that the degradation of HPMC chemical bonds was responsible for the loss of underwater anti-dispersion properties in the geopolymer paste. The workability of the paste was negatively impacted by the thickening effect of HPMC. As the HPMC content increased, both the yield stress and plastic viscosity of the paste rose. FA enhanced the paste's workability, increasing its flowability by 13.36 %. At a constant alkali content, the rheological behavior of the paste was significantly affected by the HPMC content and the GBFS/FA ratio. The Bingham and modified Bingham (MB) models were employed to fit the rheological curve of the geopolymer paste, yielding satisfactory results. While GBFS contributed to the improvement of early strength, FA had a contrary effect. HPMC could delay the hydration process, increase the porosity of geopolymers, and reduce the strength of the samples. Underwater pouring further exacerbated the porosity, negatively affecting the geopolymer's strength. This study offers valuable insights for the application of geopolymers in underwater engineering.

Effects of Polymer-Curing Agent Ratio on Rheological, Mechanical Properties and Chemical Characterization of Epoxy-Modified Cement Composite Grouting Materials.

This study designs and uses water-borne epoxy resin (WBER) and curing agent (CA) to modify traditional cement-based grouting for tunnels. The purpose of this paper is to analyze the rheological and mechanical properties of composite grouting with different ratios of WBER and CA and analyze the modification mechanism by means of chemical characterization to explore the feasibility of WBER as a high-performance modifier for tunnel construction. The composite grouting is prepared by mixing cement paste with polymer emulsion. A series of experiments was carried out to investigate the effects of WBER and CA, including the slump test, viscosity, rheological curve, setting time, bleeding rate, grain size distribution, zeta potential, compressive and splitting tensile strength, X-ray diffraction(XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), on the composite grout. The results show that WBER improves grout fluidity, which decreases in combination with CA, while also reducing the average particle size of the composite grout for a more rational size distribution. Optimal uniaxial (38.9%) and splitting tensile strength (48.7%) of the grout are achieved with a WBER to CA mass ratio of 2:1. WBER accelerates cement hydration, with the modification centered on the reaction between free Ca2+ and polymer-OH, significantly enhancing the strength, fluidity, and stability of the polymer-modified composite grout compared to traditional cement-based grouting.

Research on Vault Settlement during Three-Step Tunnel Construction Process Based on Sandstone Rheological Experiment.

Tunnel stability is influenced by the rheological properties of the surrounding rock. This study, based on the Ganshen high-speed railway tunnel project, examines the rheological characteristics of siltstone and sandstone through laboratory tests and theoretical analysis. Rheological curves and parameters are derived, revealing the time-dependent deformation mechanisms of the surrounding rocks. A numerical simulation model is created using these parameters to analyze deformation and stress characteristics based on different rock levels and inverted arch closure distances. Results indicate that sandstone follows the Cvisc model, with the Maxwell elastic modulus increasing under higher loads while the viscous coefficient decreases. The vault displacement is mainly affected by the surrounding rock strength; lower strength leads to greater displacement, which also increases with the closure distance of the inverted arch. These findings are crucial for determining the optimal closure distance of inverted arches in sandstone conditions.

The Effect of Dense and Hollow Aggregates on the Properties of Lightweight Self-Compacting Concrete.

The development of self-compacting lightweight concretes is associated with solving two conflicting tasks: achieving a structure with both high flowability and homogeneity. This study aimed to identify the technological and rheological characteristics of the flow of concrete mixtures D1400…D1600 based on hollow microspheres in comparison with heavy fine-grained D2200 concrete and to establish their structural and physico-mechanical characteristics. The study of the concrete mixtures was carried out using the slump flow test and the rotational viscometry method. The physical and mechanical properties were studied using standard methods for determining average density and flexural and compressive strength. According to the results of the research conducted, differences in the flow behaviors of concrete mixtures on dense and hollow aggregates were found. Lightweight concretes on hollow microspheres exhibited better mobility than heavy concretes. It was shown that the self-compacting coefficients of the lightweight D1400...D1600 concrete mixtures were comparable with that of the heavy D2200 concrete. The rheological curves described by the Ostwald-de Waele equation showed a dilatant flow behavior of the D1400 concrete mixtures, regardless of the ratio of quartz powder to fractionated sand. For D1500 and D1600, the dilatant flow behavior changed to pseudoplastic, with a ratio of quartz powder to fractional sand of 25/75. The studied compositions of lightweight concrete can be described as homogeneous at any ratio of quartz powder to fractional sand. It was shown that concrete mixtures with a pronounced dilatant flow character had higher resistance to segregation. The value of the ratio of quartz powder to fractional sand had a statistically insignificant effect on the average density of the studied concretes. However, the flexural and compressive strengths varied significantly more in heavy concretes (up to 38%) than in lightweight concretes (up to 18%) when this factor was varied. The specific strength of lightweight and heavy concrete compositions with a ratio of quartz powder to fractional sand of 0/100 had close values in the range of 20.4...22.9 MPa, and increasing the share of quartz powder increased the difference between compositions of different densities.

ANALYSIS OF THE CHANGE IN THE RHEOLOGICAL CURVE OF THE FLOW OF NON-NEWTONIAN OILS IN THE FIELDS OF WESTERN KAZAKHSTAN

In order to improve oil recovery technologies, the task of studying the rheological properties of oil, which largely determine the development indicators of the development target, namely, the rate of oil withdrawal, the stability and nature of the movement of the front of displacement of oil by water or gas, and, as a result, final oil recovery, is becoming urgent. In this regard, there is a need for in-depth studies of the rheoviscidity properties of produced oils.This article presents the results of laboratory studies to study the rheological characteristics of both high-paraffin and heavy high-viscosity oils using the example of oil from fields in Western Kazakhstan. Since structured oils are thixotropic systems, all experiments were carried out with the same degree of structure destruction in oil, both anhydrous oils and those with different water cuts were studied. The authors also showed the nature of the change in the rheological curve of the flow of oil emulsion of various water cuts to identify the temperature interval where non-Newtonian properties of various oils are manifested. Their main physical and chemical properties are also given, and kinematic viscosities of oil with different densities are compared. The results of laboratory studies of viscosity change with temperature increase for Karazhanbas oil emulsion with different water cut are considered. Despite differences in viscosity values of different degrees of watered samples of highly paraffinic oil, the tendency of oil viscosity change depending on the shear gradient is the same. The formation of structured systems of resin and asphaltene particles is observed in flows with relatively low shear gradients. As a result, oil viscosity dependence on the shear gradient in the range of low values from 0 to 20 s-1 must be taken into account when solving tasks for high-paraffin production. The results obtained are of practical interest, since when creating a compositional model and technological modeling of the collection and transport system, the rheological characteristics of the oil of a particular field, as well as the presence of thixotropic properties, must be taken into account.

Evolution of local relaxed states and the modeling of viscoelastic fluids

We introduce a class of continuum mechanical models aimed at describing the behavior of viscoelastic fluids by incorporating concepts originated in the theory of solid plasticity. Within this class, even a simple model with constant material parameters is able to qualitatively reproduce a number of experimental observations in both simple shear and extensional flows, including linear viscoelastic properties, the rate dependence of steady-state material functions, the stress overshoot in incipient shear flows, and the difference in shear and extensional rheological curves. Furthermore, by allowing the relaxation time of the model to depend on the total strain, we can reproduce some experimental observations of the non-attainability of steady flows in uniaxial extension and link this to a concept of polymeric jamming or effective solidification. Remarkably, this modeling framework helps in understanding the interplay between different mechanisms that may compete in determining the rheology of non-Newtonian materials.

Application and Optimization of Rheological Mathematical Models in Preparation and Injection Process of Polymer Flooding

The impact of shear on the properties of polymer solutions is not fully accounted for in the simulation of conventional rheological models. To optimize the application of these mathematical models, the shear rheological characteristics of polyacrylamide at various concentrations were investigated under different shear rates and shear modes. The results indicate that pseudoplastic fluid polymers exhibit two distinct rheological characteristics within their "shear thinning" rate range. The critical shear rate at this threshold signifies the point at which shear stress begins to disrupt the structure of the polymer solution, resulting in a rheological curve that transitions from high to low shear rates without reverting back to a low-to-high state. The concentration of the solution has minimal effect on the critical shear rate of the polymer, which is primarily determined by the inherent properties of the polymer itself. The application of rheological models during preparation and injection processes can elucidate the effects of shear on polymers by analyzing changes in apparent viscosity. Furthermore, the rheological model following supercritical shear rates requires modifications to the consistency coefficient (K) and flow index (n) based on shear rheological data obtained from high to low shear rates.

On pressure-driven Poiseuille flow with non-monotonic rheology.

Shear thickening fluids are liquids that stiffen as the applied stress increases. If many of these types of fluids follow a monotonic rheological curve, some experimental and numerical studies suggest that certain fluids, like cornstarch, may exhibit a non-monotonic, S-shaped rheology. Such non-monotonic behavior has however proved very difficult to observe experimentally in classical rheometer. To explain such difficulties, the possible presence of vorticity banding in the rheometer has been considered. To prevent such instabilities, we use a capillary rheometer, which is a cylindrical tube, measuring the flow rate versus the applied pressure drop. With this setup, we indeed observe a non-monotonic behavior: the flow rate increases monotonically at low pressure drops up to a maximum, after which it abruptly decreases to an almost constant flow rate regardless of further increases in pressure drop. This maximum-jump-plateau behavior occurs over a wide range of concentrations and is reproducible without hysteresis, which is in agreement with an S-shaped rheology. However, the obtained flow versus pressure difference function does not agree with the classical Wyart-Cates rheological model, which predicts an S-shaped non-monotonic function, but with neither a jump nor a plateau. To understand this jump-plateau behavior, we remark that any rheological model would establish a relationship between the flow rate and the local pressure gradient, but not the total pressure drop. We thus discuss and analyze the implications of having an S-shaped non-monotonic flow rate-pressure gradient in Poiseuille flow. In particular, we discuss the possibility of a non-uniform pressure gradient in the direction of the flow, i.e., a kind of streamwise banding. The key issue is then the selection of the gradient pressure distribution along the tube. One solution could arise from an analogy of this problem with the spinodal decomposition. It, however, leads to an increase in flow rate with up to a plateau between two values of as determined by the Maxwell construction. To account for the bump-jump behavior, we have implemented a simple dynamical stochastic version of the Wyart-Cates model, where the thickening occurs with a characteristic time. As a result, with increasing the total pressure drop, the flow rate increases monotonically up to a maximum value. Beyond this point, the flow rate drops abruptly to a lower value, forming a slowly decreasing plateau. This behavior is likely to account for the maximum-jump-plateau observed in the experiments. We also show that in such a system, the final state is quite sensitive to the initial state of the fluid, especially its homogeneity. Our results then demonstrate that the mere presence of a non-monotonic rheological curve is sufficient to predict the occurrence of stress banding in the streamwise direction and a plateau flow rate, even if the suspension remains homogeneous.

Resting time effects on flow properties of cementitious materials: a study on self-compacting concrete equivalent mortar made with recycled aggregates

The concrete equivalent mortar (CEM) method, mainly used in the laboratory, offers a course that facilitates and accelerates experimental test programs with relatively small amounts of materials. To this end, two CEM mixes, with natural and recycled aggregates, at different superplasticizer (SP) concentrations, were tested. The key objective was to investigate how CEM flow property changed at 0, 30, and 60 min of resting time, emphasizing the material’s structuring and destructuring effects. This study describes the flow behaviour of CEMs applying specific tools. Also, a vane-geometry rheometer was used to obtain rheological flow curves. Whatever the SP content in the structuring state, the results indicated reduced flow properties over time. However, an SP content of 1.3% retard the structural build-up property that was not evident at 60 min-rest time. Spread diameters ranging between 300 and 400 mm are measured with the mini cone immediately after mixing. After 60 min of resting time, these diameters were reduced between 260 and 300 mm. Remixing after prolonged rest periods reduces the flow stress values, which decrease from 10 to 18 Pa to 6 to 14 Pa. After a structural build-up at a rest time, the structural break-down effect by remixing re-fluidifies the mixtures. The fluidity has recovered its initial state, reflecting a thixotropic property.

Synthesis and rheological performance of shear-thickening waterborne polyurethane

Shear-thickening fluids (STFs) are a new type of intelligent material with excellent performance whose viscosity increase sharply with the increase of shear rate or shear stress. However, the synthesis yield of dispersed phase particles is low, and the particle re-dispersion process is challenging for the industrial production of STFs. In this work, through structural design, a waterborne polyurethane (WPU) with typical shear-thickening properties was synthesized for the first time. This synthesis process is conducive to industrial production. The rheological properties of the synthesized WPU at different concentrations, temperatures, and pH were studied using a rheometer. The results showed that the WPU exhibited typical shear-thickening behavior. However, due to the special core–shell structure of the WPU particles, the shear rate has two transition responses to the shear-thickening behavior. With increasing concentration, the shear-thickening performance of the WPU is enhanced, and the critical shear rate is decreased. For the coexistence of Brownian motion and solvation, the rheological curve of the WPU exhibits a complex response to temperature increase; its shear-thickening behavior decreases with rising temperature, but the viscosity first decreases and then increases with temperature. Due to the presence of carboxyl groups on the surface of the WPU particles, its shear-thickening performance shows a strong response to pH. By appropriately adjusting the pH, the viscosity and particle size of the WPU can be increased through the ionization of carboxyl groups, thereby enhancing the shear-thickening behavior.

Fracturing behavior and damage model of spatial-rotation fissured sandstone: An experimental study on freeze–thaw and fatigue loads coupling

Earthquake exposure can greatly weaken the mechanical properties and affect the failure process of fractured rocks in cold regions. Creep tests of the spatial-rotation (SR) fissured rock with sandstone as the bedrock under different fatigue combinations and angles were carried out. The effects of freeze–thaw and fatigue loads (FT-FLs) on the deformation behaviour of samples, for example, creep, fatigue deformation, frost heave pressure, and creep rate, were explored. The mechanical responses and failure modes of the specimens were analysed in detail. Based on the experimental results, a new coupled damage model was explored. The results show that in addition to the typical creep stage, the rheological curve also included the phase of disturbance deformation under fatigue loading. The attenuation rates of the rock samples had downward trends with increasing load level under the fatigue combinations and angles, and these decreasing trends had linear characteristics. Moreover, the fatigue rate values increased gradually as the fatigue amplitude, fissure angle and rotation angle increased. In addition, with the change in the fissure and rotation angles, the curves of the tensile crack number had inverted U-shaped trends. The 3D fracture patterns under fatigue were dominated by vertical and vertical-lateral penetration, in which secondary fissure expansion also occurred at different angles. A combined damage model based on the damage variable of freeze–thaw cycles, fatigue loading, and spatial rotation of fissures was established. Compared with test data and other models, the coupled model has good accuracy in describing the entire failure process of specimens under FT-FLs and provides a new framework for the stability of fractured rock masses.

Impact of the functionalized clay nanofillers on the properties of the recycled polyethylene terephthalate nanocomposites

AbstractPolymer nanocomposites, such as polyethylene terephthalate (PET)‐clay systems, leverage intricate interactions between components to fine‐tune their thermal, mechanical, and rheological properties. In our study, we functionalized montmorillonite clay nanofillers (CloisiteNa+) to fabricate recycled PET‐clay nanocomposites. The nanofillers underwent a three‐step functionalization process, involving the treatment with (3‐Aminopropyl)triethoxysilane (APTES), the grafting of initiating coatings (multifunctional peroxide initiator, [MPI]) onto clay/APTES, and the subsequent fabrication of grafted brushes using poly(butyl methacrylate) (PBMA) or poly(butyl acrylate) (PBA). The functionalization process and the properties of the modified clay were successfully confirmed through Fourier‐transform infrared spectroscopy and thermogravimetric analysis. The fabrication of nanocomposites, incorporating both clay and functionalized clay, influenced the thermal behavior of the composites, whereas the nanofillers had no discernible impact on the flow temperature. The PET and nanocomposites exhibited liquid viscoelastic behavior, with the exception of PET with clay, which displayed shear‐thinning and “rubber‐like” behavior. Rheological curves and x‐ray diffraction (XRD) analysis indicated improved dispersion and compatibility for clay/APTES and clay functionalized with PBA‐grafted brushes within the PET matrix. In some instances, the utilization of functionalized clay resulted in enhanced compatibility and customized properties in PET‐organoclay nanocomposites compared with conventional fillers. These findings bear implications for a broad spectrum of applications involving PET‐organoclay nanocomposites.

RHEOLOGY OF STRUCTURED LIQUIDS. ADDICTION DYNAMIC MOD-ULES FROM STRAIN AMPLITUDE

A new interpretation is proposed for the dependence of dynamic moduli on the deformation amplitude during shear vibrations occurring at a xed vibration frequency. It is based on a structural rheological model, which includes the kinetic equations for the formation and destruction of particle aggregates under the action of an oscillating shear flow. Rheological equations have been obtained that are able to approximate rheological curves in separate sections with different amplitudes of shear deformation. The possibilities of the new rheological model are shown on the example of two polymer systems filled with solid particles.

Rheological characterization of the conditioned sandy soil under gas-loading pressure for earth pressure balance shield tunnelling

Soil conditioning technology is usually required to modify the excavated soil to a fluid plastic state during the construction with earth pressure balance (EPB) shield. The steady pressure distribution in the excavation face is linked to soil fluidity. Compared with the slump test, the rheological behavior of the conditioned soil can better reflect the dynamic flow characteristics. A gas-loading rotational rheometer is developed to test the rheological properties of the conditioning agents and the conditioned sandy soil, which can overcome the disadvantage of uneven mechanical loading and create gas-loading conditions. The rheological properties of sandy soil conditioned by different agents under atmospheric and gas-loading pressure conditions were studied, and the influences of foam injection ratio (FIR), bentonite slurry injection ratio (SIR), and polymer injection ratio (PIR) on soil viscosity were analyzed. The test results show that the ambient air pressure only greatly influences the experimental group with foam. Under the same gas-loading pressure, the foam’s apparent viscosity decreases with the foam expansion ratio (FER) increasing. The rheological behavior of the conditioned sandy soil conforms to the Bingham model under atmospheric pressure and conforms to the Power Law model when PIR ≤ 5 % under gas-loading pressure of 3 bar. The Weissenberg effect accounts for the differences. When PIR > 10 %, the rheological curve of three agents conditioned sand conforms to the Herschel Bulkley model. The higher content polymer reacts with bentonite to increase the soil viscosity, and blocks the foam seepage channel, making it difficult for the foam to re-enter the soil under gas-loading pressure. Investigating the rheological behavior of different conditioned sandy soil provides optimization strategies for EPB performance.

Thermal deformation behavior investigation of Ti–10V–5Al-2.5fe-0.1B titanium alloy based on phenomenological constitutive models and a machine learning method

The two-phase titanium alloy Ti–10 V–5Al-2.5Fe-0.1 B was taken as the experimental material, and thermal compression experiments were carried out at a deformation temperature of 770–920 °C and a strain rate of 0.0005–0.5 s−1. An Arrhenius model, a modified Johnson-Cook model, and an improved BP neural network model based on the sparrow search algorithm (SSA-BP) model were established to predict the high temperature rheological stress of the alloy. A comparison of the prediction accuracy of the three models was made. When the partial random data in the rheological curves was used for model building and relatively independent data were used for predicting the rheological stress, the SSA-BP model had higher prediction accuracy, which exhibits the highest mean square correlation coefficient (R2) value of 0.9992 and the lowest root mean square error (RMSE) and average absolute relative error (AARE) values of 1.3031, and 2.0947 %, respectively. The ability of three models to predict the rheological stress for the new process parameters was verified. Results show that the SSA-BP model still has better prediction ability, which exhibits the highest mean square correlation coefficient (R2) value of 0.9720 and the lowest root mean square error (RMSE) and average absolute relative error (AARE) values of 5.0099, and 6.0382 %, respectively. The predicted values of SSA-BP for the rheological stress were used to construct the hot processing map. Results show that the trend of the power dissipation factor (η) value from the hot processing map predicted by SSA-BP can well agree with the microstructure evolution of the alloy.

Dynamic-Mechanic Analysis and Rheological Modelling of Waste Face Mask Modified Bitumen

Due to the Covid-19 global pandemic, the use of face masks has increased considerably in recent years. Used face masks are released into our environment and become a severe environmental threat. Therefore, researchers have focused on the recycling of waste face masks. Recently, studies have been carried out on the use of waste face masks as additives in bituminous materials, but a detailed rheological characterization has not been made. In this study, modified bitumens were obtained by adding 1%, 1.5%, 2%, 2.5%, and 3% waste face mask (WFM). Subsequently, frequency sweep test was performed on modified bitumen samples through a Dynamic Shear Rheometer (DSR). Thus, the viscoelastic behavior of WFM modified bitumen was investigated at different temperatures and loading rates. Performance analysis was conducted with rheological master curves, which were characterized according to analytical and mechanistic models. In this study, rheological evaluations were performed according to the Christensen-Anderson (CA) Model, Christensen-Anderson-Marasteanu (CAM) Model, Sigmoidal Model (SM), and finally, the mechanistic Huet-Sayegh Model (HSM). According to the results, it was determined that WFM significantly increased the rutting resistance of bitumen and performed better at low and high loading rates than the pure bitumen at each WFM ratio.

Exploring the interplay between thermo-oxidative degradation and asphalt aging in thermoplastic polyurethane-modified asphalt: Mechanisms, properties, and performance evolution

The aging behavior of thermoplastic polyurethane-modified asphalt (TPUMA) is intricate and the mechanisms of its thermal degradation are not well understood. This study examines the viscoelastic, chemical and morphological characteristics of thermoplastic polyurethane modified asphalt (TPUMA) under different aging conditions (RTFOT/PAV). The rheological master curve model of the S parameter was used to analyze the fitting effect on TPUMA, with SBS (styrene–butadiene–styrene) modified asphalt serving as the control group. The relationship between the phase angle plateau area and polymer aging degradation was elucidated. This study investigates the impact of polymer degradation on the high-temperature rheological behavior and medium-temperature fatigue properties of asphalt through temperature sweep, multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Fourier transform infrared spectrometer (FTIR) and confocal laser scanning microscopy (CLSM) are used to qualitatively and quantitatively analyze the chemical composition and morphological evolution of TPUMA during thermal-oxidative degradation. The findings suggest that TPUMA's performance changes in the aging environment is result from the dual coupling effect of polymer degradation and asphalt oxidative hardening. The closely arranged isocyanate (-NCO) and polar component molecular chains in asphalt slow down its oxidation speed, which enhances the aging and deformation resistance of TPUMA. The successful blending of TPU and asphalt was confirmed, and the degradation degree of the polymer was quantitatively characterized by the percentage of the degraded area. The results provide insights to better understand the interplay between TPU degradation and asphalt oxidation.

Influence of temperature effect on properties of modified magnesium slag-based low-carbon paste backfill materials

Coal mining subsidence and bulk solid waste storage are the bottleneck problems for achieving green and low-carbon development in northern Shaanxi. Aiming at the demand of filling mining in coal mines in northern Shaanxi, a modified magnesium slag-based low-carbon paste backfill materials (MMS-PBM) was proposed, which realized the safe disposal and resource utilization of solid waste. In-depth understanding of the influence of temperature effect (initial temperature: 5 ∼ 50 °C and curing temperature: 20 ∼ 50 °C) on the performance of MMS-PBM is helpful to optimize the mix ratio and filling period of filling materials. Based on this, relevant tests and tests (including setting time test, Mini-slump test, rheological test, uniaxial compressive strength test, microscopic test and leaching toxicity test) were carried out to explore the influence mechanism of temperature effect on the performance of MMS-PBM. results showed: (1) The rheological curve of fresh MMS-PBM slurry is highly consistent with the Herschel-Bulkley (H-B) model, and the fluidity meets the pumping requirements of coal mine filling. With the increase of initial temperature, the yield stress and apparent viscosity of fresh slurry increased, while slump, expansion and thixotropy decreased. (2) The increase of initial temperature inhibits the development of early mechanical properties of MMS-PBM, which is mainly affected by the metastable film hypothesis. (3) The curing temperature is conducive to the development of mechanical properties of MMS-PBM, and meet the requirements of mechanical properties of coal mine. With the increase of curing temperature, the main growth range of mechanical properties gradually changes from 7–28 d to 3–7 d, which is consistent with the change of microstructure. (4) The leaching concentration of heavy metals in MMS-PBM meets the requirements of national standards, but the increase of curing temperature has an inhibitory effect on the solidification of heavy metals. The above results show that MMS-PBM is a safe, green and low-carbon all-solid waste filling material, which is beneficial to the coordinated development of coal resource mining and environmental protection.

Enhancement of Starch Gel Properties Using Ionic Synergistic Multiple Crosslinking Extrusion Modification.

Crosslinking is a promising method to modulate the gel properties of food-grade starch gels. Still, the poor crosslinking effect of a single type of crosslinker limits the application of this method in starch gel modification. In this study, an Ca2+ synergistic multiple crosslinking modification method was proposed to prepare crosslinked starches with good gel properties and setting. The rheological properties of the samples were tested. The modified sample (SC-Ca-N3, G' = 1347 ± 27) showed a 79% improvement compared to the starch without synergistic crosslinking modification (SC-N, G' = 752 ± 6). The elastic modulus of starch gels can be adjusted by changing the degree of the crosslinking reaction. The results of nonlinear rheological Lissajous curve analysis showed that the synergistically crosslinked gel system strongly resisted deformation. In addition, the microstructure of the modified samples was characterized using scanning electron microscopy. The XPS, FTIR, and XRD results indicated that multiple molecular forces participate in the synergistic crosslinking reaction.