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Heavy crude oil (HCO) production, processing, and transportation forms several practical challenges to the oil and gas industry, due to its higher viscosity. Understanding the shear rheology of this HCO is highly important to tackle production and flow assurance. The environmental and economic viability of the conventional methods (thermal or dilution with organic solvents), force the industry to find an alternative. The present study was constructed to investigate the effect of eco-friendly ionic liquids (ILs) on the HCO's rheology, at high temperature and high pressure. Eight different alkyl ammonium ILs were screened for HCO's shear rheology at the temperatures of 25–100 °C and for pressures 0.1–10 MPa. The addition of ILs reduced the HCO's viscosity substantially from 25 to 33% from their original HCO viscosity. Also, it aids to reduce the yield stress to about 15–20% at all the studied experimental conditions. Furthermore, the viscoelastic property of the HCO was studied for both strain-sweep and frequency-sweep and noticed the ILs helps to increase HCO's loss modulus (G″) by reducing storage modulus (G′), it leads to the reduction of the crossover point around 25–32% than the standard HCO. Mean the ILs addition with HCO converts its solid-like nature into liquid-like material. Besides, the effect ILs chain length was also studied and found the ILs which has lengthier chain length shows better efficiency on the flow-ability. Finally, the microscopic investigation of the HCO sample was analyzed with and without ILs and witnessed that these ILs help to fragment the flocculated HCO into smaller fractions. These findings indicate that the ILs could be considered as the better alternative for efficient oil production, processing, and transportation.

High-belite cement (HBC) is increasingly used in hydraulic concrete, of which the frost resistance is an important index in cold climatic areas. In the present study, the mass loss, dynamic modulus, cube compressive strength, micro-morphology and pore characteristic parameters of HBC concrete and reference specimens were investigated under freezing and thawing, and their internal frost damages were quantified by micro-Vickers hardness and ultrasonic theory. Test results showed that the frost resistance of HBC concrete was similar to that of ordinary Portland cement (OPC) concrete under the same proportioning, and that their freeze–thaw failure was a continuous and asynchronous process of both surface-to-interior damage and overall deterioration caused by the test mechanism and specimen size. Service life of concrete could be calculated through the thickness of the damaged layer obtained by ultrasonic theory, and models of Vickers hardness distribution and compressive strength prediction based on equivalent Vickers hardness were proposed to evaluate the performance of frozen concrete with high accuracy. This potentially provides a better understanding of freeze–thaw damage and a reference for the popularisation and application of HBC concrete.

Background: Formulation of topical products for skin delivery that fulfill good formulation criteria has always been a challenge for pharmaceutical scientists. Despite the challenges, gelbased drug delivery offers some advantages such that it is non-invasive, painless, involves avoidance of the first-pass metabolism, and has satisfactory patient compliance. Objectives: In this study, C. odorata gel and quercetin gel (bioactive flavonoid compound) were successfully formulated and compared with placebo and conventional wound aid gel. The chromatographic profiling was conducted to screen the presence of phytoconstituents. Subsequently, all formulated gels were evaluated for physical characteristics and stability. Methods: Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) of C. odorata methanolic leaves extract showed a distinct compound separation at a retention time of 8.4min to 34.8 min at 254nm. All gels were characterised by evaluating their rheological properties, including storage modulus, loss modulus, and plastic viscosity. Besides, texture analysis was performed to measure the firmness, consistency, cohesiveness, and viscosity index of the gels. Results: According to the results, C. odorata gel demonstrated better spreadability as compared to the other gels, which required less work and was found to be favourable for application on the skin. Moreover, C. odorata gel showed no changes in organoleptic properties and proven to be stable after 30 days of accelerated stability study at 40°C ± 2°C with Relative Humidity (RH) of 75% ± 5%. Conclusion: C. odorata gel was found to be stable, reflecting the combination of materials used in the formulation, which did not degrade throughout the study. This work suggests the potential of this gel as a vehicle to deliver the active ingredients of C. odorata to the skin, which can be further explored as a topical application for antimicrobial wound management or other skin diseases study.

Warm Mix Asphalt (WMA) is a set of technologies that uses additives to reduce binder viscosity and increase mixture workability, which provides a complete coating of aggregates at lower temperatures around 100 °C to 130 °C. Organic wax or Sasobit is one of the additives that can be used for this purpose. It reduces the viscosity at the melting point of the wax, which allows the production of asphalt mixes at lower temperatures. This attempt proposes new relationships for elastic modulus, indirect tensile strength (in dry and wet conditions), dynamic modulus, fatigue, and rutting resistance of WMA asphalt samples with various Sasobit percentages. Findings show that Sasobit improves modulus of elasticity, dynamic modulus, and rutting resistance. However, it lessens the tensile strength slightly. Although Sasobit enhances the flexural stiffness, it drops the number of loading cycles, which means lower fatigue resistance. Results also showed that at 20 °C and 10 Hz frequency, the resilient modulus, dynamic modulus, and flexural stiffness of WMA improved 53%, 27%, and 39%, respectively, compared with HMA. Rutting resistance at 60 °C improves 226% in WMA with 6% Sasobit compared to the HMA mix.

Assessing concrete quality as construction goes on provides early warnings of potential flaws and leads to timely corrections in mix proportioning and placement techniques. Compressive strength and maturity modeling are among the most common parameters used by the concrete industry. Past studies indicated that non-destructive methods, NDTs, relate well to maturity and concrete strength predictions. In this study, the hydration temperature–time history of concrete was explored in defining “master curves” for concrete maturity for the first time. Well-accepted NDTs, such as ultrasonic pulse velocity and resonant frequency, were used in this effort. The study findings indicated that the novel approach of “master curves” for the maturity of concrete can be defined and follow a generalized logarithmic form. The best fit models relating NDT response and the maturity temperature–time product provided a high coefficient of determination (i.e., in almost all cases above 0.9 and p < 0.05), thus resulting in a very good fit. The shift factors for each mixture’s maturity function in relation to the master curve were related to concrete properties. The shifted maturity functions from the concrete mixtures included in the study had a perfect transition to the master curve (i.e., all the shifted data overlap the master curve trend line with an R2 = 1). The NDTs’ ability to capture the hydration temperature-time history was assessed with impeded sensors into the concrete mixtures. This approach has provided strength prediction models with a high accuracy (i.e., good agreement between observed and predicted strength values with R2 = 0.93). The proposed NDT-based maturity modeling through “master curve” development provides significant benefits in relation to traditional maturity modeling since it offers the opportunity to: (i) predict strength without having to repeat maturity testing each time a producer adjusts mixture proportioning to fine tune mix design; (ii) save testing time and cost due to reduced maturity evaluation from the use of master curves; and (iii) be able to quickly predict without further testing what the strength gain will be due to variations in mixture proportioning. The ability to monitor concrete maturity, and thus strength, with NDTs in reinforced concrete is of particular interest since using cores is problematic due to the presence of reinforcement.

Funding Information: This work was supported by National Key R&D Program of China (No. 2021YFB2601005) National Key R&D Program of China (No. 2018YFE0103800), National Science Foundation of China (No. 5217081949), National Natural Science Foundation of China (No. 51978068), Inner Mongolia Transportation Research Project (No. NJ-2021-17), and the Fundamental Research Funds for the Central Universities, CHD (No. 300102212210). The authors gratefully acknowledge their financial support. Publisher Copyright: © 2023 by the authors. High-modulus asphalt mixture (HMAM) is one of the most effective materials to enhance the rutting resistance of asphalt pavement and upgrade pavement sustainability. The objectives of this study are to investigate the modulus properties of different HMAMs and their correlation with the rutting resistance, to propose reasonable modulus evaluation indicators, and to analyze the rutting resistance mechanisms of different materials (hard asphalt, polyethylene, dissolved polyolefin). The effect of three HMAMs and two styrene-butadiene-styrene (SBS) modifiers on asphalt mixtures’ rutting resistance were evaluated by dynamic modulus test and wheel track test, and the results were simulated and further analyzed via ABAQUS. The results indicate that the dynamic modulus of the mixtures showed a gradual increase and decrease with the increase of loading frequency and testing temperature, respectively. The ratio of dynamic modulus in low frequency to that in high frequency correlates well with dynamic stability under high-temperature conditions, and the wider the frequency coverage, the higher the correlation between this ratio and dynamic stability. The rutting resistance of asphalt pavements can be improved by reducing the frequency sensitivity of HMAMs under high temperatures or by increasing the modulus’ absolute value of the pavement structural layer. Therefore, two indicators, the absolute value of the modulus and the ratio of 0.1 Hz dynamic modulus to 25 Hz dynamic modulus at 55 °C, are recommended for the evaluation of rutting resistance of HMAMs. Based on the evaluation indexes proposed in this paper, a comparative analysis of the rutting resistance mechanism of HMAMs prepared with different materials was carried out, and it was concluded that the mixture with high-modulus agents had the best rutting resistance, which is consistent with the test road observations, thus verifying the feasibility of the modulus evaluation indexes recommended in this paper for the evaluation of the rutting resistance of different typesof HMAMs.

Understanding and optimization the rheological properties characterization of zirconia (ZrO2) based ceramics inks is critical for optimizing the production of Direct Ink Writing (DIW) components to achieve complex structures with similar properties as those obtained by using the traditional processing routes. In this work, ZrO2 based ceramic materials with different yttrium contents (3 and 8 mol %) were designed and produced by DIW to determine the most suitable ceramic ink composition in terms of the rheological properties (e.g. flow curves, viscosity, loss modulus G', storage modulus G¿, etc.) to design new components. Different ceramic inks with charges up to 75 wt % were prepared and characterized. A systematic study of the feedstock, as well as the different ceramic inks, was performed to determine the optimal ceramic charge. This characterization evidences that rheological properties of zirconia based ceramic inks are influenced by the particle size and amount of ceramic content. Furthermore, the rheological study highlights that the ZrO2 inks present a Non-Newtonian behavior depending on the ceramic content. Results revealed that the yttrium content affects the flow properties of ZrO2 suspensions in such a way that, higher shear rate was required to make the suspensions flow at increasing the amount of powder. It was also found that the best rheological properties corresponded to 73 and 70% for the 3Y- and 8Y–ZrO2 of ceramic charge, respectively.

Aging can significantly affect the performance of asphalt mixtures, causing increase in stiffness, reduction in relaxation capability and increase in cracking susceptibility. It is also well known that fundamental viscoelastic properties are used for design and modelling of asphalt mixtures and pavement structures to addressing rutting, fatigue and thermal cracking concerns. The objective of this paper is to study how the viscoelastic properties of asphalt mixture change over time, and evaluate and identify the cracking and aging susceptibility of asphalt mixtures with different mix variables during material selection and mixture design. Ten mixtures are evaluated using different laboratory conditioning protocols to simulate a range of aging levels in the field. The complex modulus test is then conducted on the lab aged mixtures to measure the viscoelastic properties in order to construct the dynamic modulus and phase angle master curves. The mixture Glover-Rowe (G-Rm) parameter and the shape parameters of the dynamic modulus and phase angle master curves, including inflection point frequency (−β/γ), difference between the glassy modulus and the inflection point modulus (γ), peak value of phase angle (a) and the horizontal position (frequency) of the peak phase angle value (c), are determined and evaluated for the mixtures with different aging conditions and mix variables. The study indicates the ability of the G-Rm parameter and all the master curve shape parameters to capture the effect of different aging conditions on linear viscoelastic mixture properties, as well as the cracking and aging susceptibility of asphalt mixtures.

The environmental awareness and rapid development in the area of material science attracted the researchers into natural based materials on account of their chemical resistance, ease of fabrication, low density, specific strength, inexpensiveness and favourable mechanical properties. However, some cellulose fibres extracted from natural sources have somewhat high mechanical properties nearer to those of synthetic fibres. Composites using natural fibres as reinforcement have shown favourable results. These natural fiber reinforced composites often considered as high performance reinforcements in polymer composites. DMA had become important for both industry and academia. DMA is an effective thermal analysis tool for the determination of elastic nature of a composite material with respect to of time, frequency, temperature and combination of these. A dynamic mechanical analysis utilizes applied force and deformation data to evaluate the stiffness changes in a material under varied temperatures. DMA measures elastic nature with reference to storage modulus (E’), loss modulus (E”), damping factor (Tan delta) and glass transition temperature (Tg). These properties will be very helpful to measure the performance characteristics of polymer composite materials including both thermosets and thermoplastics. Now a days, most effective and flexible DMA instruments under different modes are available. Dynamic Mechanical Analysis (DMA) is currently used by rubber manufacturers to study the performance of their materials. For the purposes of industrial testing as well as for research and development, DMA is recognized as a highly informative characterisation technique. DMA curves depicts variation of dynamic moduli and damping in glassy or rubbery regions. The current review studies the effect of natural fibres on dynamic mechanical properties of polymer composites. Many results exhibited that inclusion of natural fibres with polymers tends to increase the elastic nature of the polymer matrix.

Regenerative medicine is used for tissue healing, replace missing organs and tissues which are affected by aging, disease, or trauma both structurally and functionally. Materials are the key component of regenerative medicine approaches because the material can imitate the native extracellular matrix of those tissues and improve both the physical behavior and the properties of new tissue. However, most of the available materials used for that purpose fail to provide adequate mechanical properties to replicate the behavior of the original tissue. Thus, most of these applications are still far from being enduring. This project aims to determine the multi-scale mechanical properties of some biopolymers with potential use in regenerative medicine. In this very first part, Dynamic Mechanical Analysis (DMA) was performed using shear mode on different type VII agarose-based biopolymers at room temperature during 10 min cycles at 1 Hz frequency. On one hand, samples of fibrine-agarose were tested, and on the other, different compositions of chitosan-agarose, while pure type VII agarose was used as control. Computed values for the storage and loss modulus and the small values for Tan delta ratio (tan δ) show that all materials become elastic, and they have a good capacity to dissipate energy per cycle of deformation. This fact means that all materials are suitable for being used as a scaffold for cell culture, a possible material for bioprinting applications and they could have potential use in regenerative medicine.

The use of nanofiller and fiber reinforced polymeric composites has risen immensely over the last decade and it finds abundant applications in the field of thermal power plants, coatings, and automotives. In this research article, the effect of nano-alumina on carbon fabric reinforced epoxy (CF/Ep) hybrid composites was investigated by microstructure, Fourier transfer infrared radiation (FTIR), X-ray diffraction (XRD) and dynamic mechanical analysis (DMA). Addition of nano-alumina increased the intensity of peak related to C–H bonds and large broad bands were initiated in the region of 865 to 820 cm−1.The Al-O-Al bonds are stretching due to vibrations in the octahedral and tetrahedral coordination. XRD analysis on CF/Ep hybrid clearly reveals the presence of nano-alumina particles. DMA demonstrates that both the storage modulus and glass transition temperature be likely to increase with the incorporation of nano-alumina. Furthermore, the loss modulus was found to be highest for the 2 wt% of nano-alumina filled CF/Ep hybrid composite

The boosting of electrical and microelectronic goods causes the continuous increase in the amount of power per unit volume of these gadgets, leading to unavoidable overheating problems that diminish their functional performance as well as life span. One of the primary aims of materials science is the creation of high-performance materials that are made from renewable resources. Multi-phase composites were recognised as an effective route to achieve a new portfolio of advanced materials with superior performance. Some of the functional fillers in polymer-based composite materials exhibit outstanding electrical insulation, chemical resistance, mechanical and processing properties, and therefore are considered to be the most promising candidates to solve the heat dissipation problem. In this research article, the thermal behavior, namely Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction Analysis (XRD), and Dynamic mechanical analysis (DMA) of hybrid nano-sized hydroxyapatite filled hybrid fiber reinforced epoxy nanocomposites are investigated. Three important parameters were examined at 1 Hz frequency: storage modulus, loss modulus, and damping, all from room temperature to 160 °C. The influence of the nHAP loading on the dynamic mechanical properties are discussed and explained with the highly relevant works from the available literature. In particular, the dependence of the hybrid composite damping on the nHAP loading was explained with regard to damping due to particle–particle and polymer-fiber interaction. The presence of nHAP is confirmed by a wider XRD curve, and the incorporation of nHAP results in the removal of the hydroxy group from the fibers as shown by FTIR. The inclusion of nHAP in a hybrid (S + B/Ep) composite enhances the synergetic effect, which raises the storage and loss modulus, decreases the damping factor, and increases the Tg of the nHAP filled hybrid nanocomposites.

Dynamic mechanical analysis (DMA) is a technique that is used to study the viscoelastic behaviour of polymeric materials. 3D printing is one of the well-known applications of additive manufacturing techniques which has wide areas of application. In that, Fusion Deposition modelling (FDM) has very fine outcomes with better printing qualities to execute good products. In this research work, the 3D printed samples of pure ABS and PLA were examined under dynamic mechanical analysis to study the various temperature heat, absorbing, storing, and dissipating behaviour of these samples. The results show, both ABS and PLA performed well under the heat flow categories. While comparing to conventional manufacturing technologies, these 3D printed DMA results are showing some excellent results. These polymeric samples may prepare as composites and used for various applications, for better outcomes and capabilities. Storage modulus, while taking the temperature values of ABS to 90 °C maximum and for PLA about 48 °C. This will happen, but this pure form of materials printed through FDM also has such a very good energy storing capacity. Considering the loss modulus energy dissipation in the form of heat started from 110 °C, this is one of the good signs on the fabricated technique and build quality of ABS. The continues decrease in the degree of crystallinity of the PLA and ABS increases the meshing strength noted in the damping factor.

In this work, the effect of Inca peanut seed albumin fraction (IPA) on the rheological, thermal and microstructural properties of native corn starch (NCS) was firstly studied. Compared to the NCS, IPA addition could obviously decrease the transparency of NCS, and the transparency of NCS and NCS-IPA suspensions decreased during the storage time. The textural paraments of NCS pastes with or without IPA reached to the maximum at a concentration of 5%. Steady shear rheological tests showed that all systems were non-Newtonian fluid, and the consistency coefficient (K) values reached to the maximum at 5% IPA concentration. The storage and loss modulus values of NCS-IPA pastes were higher than those of NCS pastes, and curves of loss angle (tan δ) indicated that all pastes were typical weak gel. With the increasing addition of IPA, DSC analysis showed that the thermal properties (To, Tp and Tc) of NCS were significantly changed, whereas, there was no distinct difference in the enthalpy. Microscopy illustrated that there were some wrinkle shrinkage and severe folds on the NCS-IPA granules. Fourier-transform infrared (FT-IR) spectroscopy showed that the hydrogen bonding was primarily interaction forces between IPA and NCS molecules.

Acrylonitrile Butadiene Styrene (ABS) materials have been widely used in automotive and other manufacturing industries. To meet the specific requirements of industry the ABS materials are enhanced by adding fillers through compounding. Very few works are found for the improvement of viscoelastic and thermal characteristics of ABS material. This work is focused to prepare the thermoplastic composites of ABS with graphite filler and to analyze the dynamic mechanical, thermal and mechanical properties of composites. Thermoplastic composites were prepared with three different weight ratios (3, 6 and 9%) of graphite powder with ABS by employing a twin-screw extruder and the scanning electron microscopy (SEM) images confirmed the proper mixing of filler material with the matrix and the samples were prepared using injection molding machine. The viscoelastic properties of the composites were investigated through dynamic mechanical analysis (DMA) with three different frequencies of (0.5, 1 and 2) Hz and the DMA results indicate that the damping properties were significantly influenced by the presence of graphite particles in ABS. It was observed that the storage modulus (E’) is higher at the frequency of 2 Hz compared to the other two frequencies (0.5 and 1) Hz, but the loss modulus was almost the same at all three frequencies. The thermal stability and mass losses of the prepared samples, thermal gravimetric analysis (TGA) was performed and the TGA graphs showed the improvement in the thermal characteristics of neat ABS due to the addition of graphite filler. The DSC thermograms of neat ABS and ABS/graphite composites indicate that the glass transition temperatures of ABS/graphite composites were increased. The tensile strength increases up to 6 wt% of graphite and drastically drops at 9 wt% of the filler content. But the flexural strength of the ABS/graphite composites were reduced as the weight percentage of graphite content increases.

Dry-processed rubberized asphalt mixture has recently attracted a lot of attention as an alternative to conventional asphalt mixtures. Dry-processed rubberized asphalt pavement has improved the overall performance characteristics compared to the conventional asphalt road. The objective of this research is to demonstrate the reconstruction of rubberized asphalt pavement and evaluate the pavement performance of dry-processed rubberized asphalt mixture based on laboratory and field tests. The noise mitigation effect of dry-processed rubberized asphalt pavement was evaluated at the field construction sites. A prediction of pavement distresses and long-term performance was also conducted using mechanistic-empirical pavement design. In terms of experimental evaluation, the dynamic modulus was estimated using materials test system (MTS) equipment, the low-temperature crack resistance was characterized by the fracture energy from the indirect tensile strength test (IDT), and the asphalt aging was assessed with the rolling thin-film oven (RTFO) test and the pressure aging vessel (PAV) test. The rheology properties of asphalt were estimated by a dynamic shear rheometer (DSR). Based on the test results: (1) The dry-processed rubberized asphalt mixture presented better resistance to cracking, as the fracture energy was enhanced by 29–50% compared to that of conventional hot mix asphalt (HMA); and (2) the high-temperature anti-rutting performance of the rubberized pavement increased. The dynamic modulus increased up to 19%. The findings of the noise test showed that at different vehicle speeds, the rubberized asphalt pavement greatly reduced the noise level by 2–3 dB. The pavement M-E (mechanistic-empirical) design-predicted distress illustrated that the rubberized asphalt pavement could reduce the IRI, rutting, and bottom-up fatigue-cracking distress based on a comparison of prediction results. To sum up, the dry-processed rubber-modified asphalt pavement has better pavement performance compared to the conventional asphalt pavement.

For the concerns of investigating the viscoelastic properties of recycled asphalt mixtures incorporating high content reclaimed styrene-butadiene-styrene (SBS) modified asphalt pavement (RAP-SBS), asphalt mixture performance tester (AMPT) was applied to analyze the dynamic modulus and phase angle of recycled mixtures by the influence of RAP-SBS content, temperature, loading frequency, long-term aging (LOTA), and the incorporation of a rejuvenating agent. Master curves of recycled asphalt mixture regarding dynamic modulus and phase angle are developed, and the viscoelastic properties of recycled mixtures within a wide frequency range are characterized with the Christensen–Anderson–Marastean (CAM) model. Eventually, the one-way analysis of variance (ANOVA) was applied to investigate the role of factors on the viscoelasticity of recycled mixtures. The research indicates that (1) the elastic component of recycled mixtures elevates with the increasing of RAP-SBS content and loading frequency; as a result, the high-temperature stability of it enhances, while it is prone to cracking at low temperatures; (2) RAP-SBS content should be selected according to specific characteristics of pavement. For most cases, a content of 50% is recommended; (3) the recycled mixtures incorporating high-content RAP-SBS mixed with a rejuvenating agent has outstanding aging resistance performance; (4) RAP-SBS content is observed to have a significant influence on the viscoelasticity of recycled mixtures.

International audience; Based on the spectral element method (SEM) and a convolutional neural network (CNN), an inversion algorithm for the dynamic modulus of concrete pavement structures is proposed in this paper. In order to evaluate the service performance of pavement structures more systematically and accurately via the existing testing techniques using a falling weight deflectometer (FWD), it is necessary to obtain accurate dynamic modulus parameters of the structures. In this work, an inversion algorithm for predicting the dynamic modulus is established by using a CNN which is trained with the dynamic response samples of a multi-layered concrete pavement structure obtained through SEM. The gradient descent method is used to adjust the weight parameters in the network layer by layer in reverse. As a result, the accuracy of the CNN can be improved via iterative training. With the proposed algorithm, more accurate results of the dynamic modulus of pavement structures are obtained. The accuracy and numerical stability of the proposed algorithm are verified by several numerical examples. The dynamic modulus and thickness of concrete pavement structure layers can be accurately predicted by the CNN trained with a certain number of training samples based on the displacement curve of the deflection basin from the falling weight deflectometer. The proposed method can provide a reliable testing tool for the FWD technique of pavement structures.

In deepwater drilling, the properties of water-based drilling fluids change remarkably due to low temperature and high pressure, which have a significant effect on lost circulation, wellbore instability and the window between pore pressure and fracturing pressure. The present work investigates the influence of low temperature and high pressure on polymer and nanoparticle (boron nitride (BN)) based drilling fluids with an aim to improve their rheological properties and fluid loss control. The amplitude and frequency sweep tests were conducted to understand the viscoelastic nature of the samples. The amplitude sweep tests confirmed the structural stability of the designed fluid within the studied sweep frequency. The study reveals that storage modulus (Gʹ) and loss modulus (Gʺ) of the samples are enhanced with increasing concentration of BN nanoparticles. Their viscoelastic range also increases due to the intermolecular interaction within the structure of the fluid in the presence of the nanoparticles. Within the linear viscoelastic range (LVER), all the samples show the dominance of elastic modulus than viscous modulus which delineates the solid-like behaviour. The results of rheological tests of drilling fluid containing BN nanoparticles indicate a significant reduction in plastic viscosity (PV), yield point (YP) and apparent viscosity (AV). The rheological studies conducted at different temperatures (from 10 °C to −5 °C) and pressures (from 7.8 MPa to11 MPa) reveal the minimum effect of pressure and temperature on the rheology of samples, which are desirable for their applications in hydrate and deepwater drilling. The filtration loss experiments conducted at 30 °C and 0.69 MPa show a large reduction in fluid loss volume (60.6%) and filter cake thickness (90%) for the sample with 0.4 wt% BN nanoparticles compared to that of the sample without nanoparticles. The filter cake permeability is also in the favourable range with 0.008 mD which shows a 94% reduction compared to the sample without nanoparticles. A regression model was developed to mathematically describe the experimental results, which demonstrates a good fitting with the statistical data of fluid loss volume, thickness and permeability of the filter cake.

This paper investigates the equivalent viscoelastic behavior of granite after different high-temperature treatments under stress waves. The equivalent viscoelastic behavior of granite after different high-temperature treatments under dynamic conditions was investigated by the pendulum impact test, while its quasi-static behavior was investigated by the uniaxial compression test. The attenuation coefficient, wave number, storage modulus and loss modulus of granite after high-temperature treatments were determined based on the pendulum impact test. A modified three-element model was proposed to describe the relationship between the equivalent viscoelastic behavior of granite and temperature. The proposed model was validated by comparing the storage modulus and loss modulus predicted by the proposed model and those based on the pendulum impact test. The results show that the attenuation coefficient and wave number increase as temperature increases. While the storage modulus and loss modulus decrease as the temperature increases. The proposed model could describe the storage modulus and loss modulus of granite after high-temperature treatment with acceptable accuracy.

A generalized model of the damper is proposed in the form of the equivalent Voigt model for viscoelastic materials, which fully correlates with the differential equation for induced oscillations in the system with a damper. The relations of parameters of the differential equation and parameters of the equivalent Voigt model with parameters of various models for viscoelastic materials and with components of the complex elastic modulus of these models are established. An approach for the assessment of the damper influence on the oscillation level of various elements in the analyzed system that occur under the impact of a coercive force of different frequencies is proposed for the mechanical system. It is presented in the form of the model with lumped parameters. Parameters of viscoelastic materials, which are suitable for use in dampers in the designed mechanical system, are determined based on obtained estimations. Thus, the proposed approach to the analysis of the behaviour of viscoelastic dampers allows us to determine the requirements for viscoelastic materials suitable for use in the designed systems. Also, it allows us to determine frequency response characteristics of dampers with known frequency dependences of storage modulus and loss modulus of the used viscoelastic materials.

PurposeThe purpose of this paper is to contribute to the solution of the fatigue damage problem of reinforced concrete frames in bending.Design/methodology/approachThe problem of fatigue damage is formulated based on the rheological–dynamical analogy, including a scalar damage variable to address the reduction of stiffness in strain softening. The modal analysis is used by the finite element method for the determination of modal parameters and resonance stability of the selected frame cross-section. The objectivity of the presented method is verified by numerical examples, predicting the ductility in bending of the frame whose basic mechanical properties were obtained by non-destructive testing systems.FindingsThe modal analysis in the frame of the finite element method is suitable for the determination of modal parameters and resonance stability of the selected frame cross-section. It is recommended that the modulus of elasticity be determined by non-destructive methods, e.g. from the acoustic response.Originality/valueThe paper presents a novel method of solving the ductility in bending taking into account both the creep coefficient and the aging coefficient. The rheological-dynamical analogy (RDA) method uses the resonant method to find material properties. The characterization of the structural damping via the damping ratio is original and effective.

Asphalt concrete (AC) overlays have been one of the most common treatments used by the Virginia Department of Transportation (VDOT) for maintaining/rehabilitating pavements. However, when the overlay is placed on existing composite pavements or cracked AC pavements, differential movements across any cracks or joints can result in physical tearing of the AC overlay. Thus, the long-term performance of many AC overlays will highly depend on their ability to resist cracking. The purpose of this study was to assess the viability of using high polymer-modified (HP) AC mixtures in Virginia as a crack mitigation technique or when deemed appropriate as a tool for increased resistance to rutting and cracking on higher volume facilities. Another objective was to assess the ability of various testing protocols to discern the performance of pavements through a comprehensive evaluation of three conventional polymer-modified (PMA) and five HP field-produced mixtures placed in Virginia. This included laboratory testing at multiple levels of complexity (basic, intermediate, and advanced) on collected asphalt binders, plant-produced asphalt mixtures, and field cores. The performance characteristics of PMA and HP mixes were evaluated in the laboratory in relation to durability and resistance to rutting and cracking. Based on the mixes tested, stone matrix asphalt (SMA) mixes showed better performance than dense-graded surface mixes (SM) regardless of the asphalt binder type. Moreover, HP mixes showed better performance than PMA mixes regardless of the mixture type. Overall, SMA-HP mixes showed the most promising performance among all evaluated mixes.

This paper proposed an algorithm to reconstruct the microstructure of asphalt mixture considering dynamic arrangement process of aggregate particles. In this method, asphalt mixture was considered to be composed of dispersed phase including coarse aggregate and air voids, and continuous phase including fine asphalt matrix (FAM). The dispersed phase materials were characterized by high-dimensional polyhedral particles. In order to reconstruct the microstructure by 1:1 in volume fraction, three basic parameters that determine the heterogeneous structure of asphalt mixture were abided in the design of digital specimen. Then, impulse-based rigid collision response was introduced to simulate the rearrangement of aggregate particles in the compaction process of asphalt mixture. In particular, the applicability of the proposed method to typical structural types of asphalt mixture was discussed. For the asphalt mixture with high air void content, the reconstructed specimen may deviate from the real structure. Furthermore, the dynamic modulus and thermal conductivity of the generated specimens were predicted by finite element method (FEM) and compared with the experimental values. The predicted dynamic modulus and thermal conductivity coincide with the experimental results well, which indicates that the proposed method is reliable for reconstructing the heterogeneous structure of asphalt mixture with relatively low content of air voids.

Advanced ceramic composites of alumina/zirconia are widely used in structural, functional and biomedical applications owing to superior physico-mechanical properties and biocompatibility. Unlike clays/bread dough, green shaping of ceramics was limited to slip casting due to insufficient plasticity. Herein, we introduce a ceramic dough forming inspired by the natural chemistry and mechanism of wheat flour dough. Ceramic blends were kneaded into a soft visco-plastic dough with vinyl polymer assuming the role of gluten matrix. A weakly linked dough matrix with a higher loss modulus enhanced the rate of powder deagglomeration and homogeneous distribution of the different phases during kneading. High plasticity index of the dough offers replication of intricate features with good dimensional retention. Dental prosthesis like root form implant, dental crown and bridge were successfully machined on a dried blank. Shape forming by this route is a viable alternative for dental prosthesis as evidenced by microstructure, strength and Weibull modulus values.

The present study focused on the dynamic mechanical performance and thermal behavior of epoxy composites reinforced utilizing pristine halloysite nanotubes (HNTs). A comprehensive analysis was carried out on the viscoelastic behavior and structure–property relationship of neat and various HNTs-reinforced epoxy nanocomposites with varying weight percentage loading of pristine HNTs. FTIR, XRD, SEM, DSC, and TGA analyses were performed to characterize the composite samples. Storage modulus (E′), loss modulus (E″), frequency sweep, and damping factor (Tan δ) were studied as a function of temperature (30–120 °C) by DMA. Furthermore, temperature-dependent dynamic parameters were investigated at oscillation frequencies of 1, 25, and 50 Hz and correlated with DSC results. SEM analysis and Cole–Cole plot confirmed the homogeneity of HNTs in an epoxy matrix. Overall, HNTs imparted an improved viscoelastic behavior to the epoxy matrix at their optimized weight percentage loading of 2% featured to have a 48% rise in storage modulus (E′) and 135% rise in loss modulus (E″) at 40 °C. HNTs were found to have plasticizing effect for epoxy nanocomposites revealed from a slight decrease in their Tg. Thus, naturally occurring environmentally benign HNTs were found a promising reinforcing agent for tailoring viscoelastic behavior of epoxy matrix with low adverse physical effects as an efficient alternative to expensive carbon nanotubes (CNTs).

This study critically examines the utility of the rheological parameters, such as phase angle δ, sinδ, complex modulus (|G*|), rutting criterion (|G*|/sinδ), fatigue criterion (|G*|sinδ), etc., in the performance grading (PG) rutting and fatigue criteria. The results show that for unmodified asphalt binders at true PG upper limiting temperature, the PG rutting criterion ‘|G*|/sinδ’ can be equated to the viscosity of the binder. The equivalence of |G*|/sinδ and viscosity is valid over a wide range of testing conditions in oscillatory and rotation shear. Consequently, the correlation of |G*|/sinδ and viscosity with rutting in asphalt pavements was similar. The PG fatigue cracking criterion is based on the energy dissipating capacity (loss modulus G″ = |G*|sinδ ≤ 5000 kPa) of ‘RTFO + PAV’ aged binders. At true PG intermediate temperature, the loss modulus and storage modulus values of ‘RTFO + PAV’ aged binders were similar since the δ values were close to 45°. Therefore, G″ as the fatigue criterion will not provide any particular benefit in predicting the fatigue performance of ‘RTFO + PAV’ aged binders. Furthermore, using δ to forecast fatigue performance may lead to inaccuracies, as fatigue cracking and δ show opposite trends after aging in asphalt binders. The rheological properties of polymer modified binders (PMBs) are better quantified at frequencies ≤ 0.1 rad/s due to the sluggish dynamics of the polymer molecules, and the correlation between the PMBs rheological properties and rutting in asphalt mixes improves at lower frequencies. Hence, analysis at lower frequencies is critical for better grading and performance evaluation in PMBs.

There is more demand for natural fiber-reinforced composites in the energy sector, and their impact on the environment is almost zero. Natural fiber has plenty of advantages, such as easy recycling and degrading property, low density, and low price. Natural fiber’s thermal properties and flexural properties are less than conventional fiber. This work deals with the changes in the thermal properties and mechanical properties of S-glass reinforced with a sodium hydroxide-treated pineapple leaf (PALF) and banana stem fibers. Banana stem and pineapple leaf fibers (PALF) were used at various volume fractions, i.e., 30%, 40%, and 50%, and various fiber lengths of 20 cm, 30 cm, and 40 cm with S-glass, and their effects on the thermal and mechanical properties were studied, and their optimum values were found. It was evidenced that increasing the fiber volume and fiber length enhanced the flexural and thermal properties up to 40% of the fiber volume, and started to decrease at 50% of the fiber volume. The fiber length provides an affirmative effect on the flexural properties and a pessimistic effect on the thermal properties. The PALF S-glass combination of 40% fiber load and 40 cm fiber length provides maximum flexural strength, flexural modulus, storage modulus, and lowest loss modulus based on hybrid Taguchi grey relational optimization techniques. PALF S-glass hybrid composite has been found to have 7.80%, 3.44%, 1.17% higher flexural strength, flexural modulus, and loss modulus, respectively, and 15.74% lower storage modulus compared to banana S-glass hybrid composite.

In this study, steady-state and oscillatory rheology of seven commercial meat sauces were investigated in the temperature range of 0–75 °C using a controlled-stress rheometer, at shear rates between 0.1 and 100 s−1 and oscillatory frequency sweeps of 0.01–10 Hz. The sauces exhibited pseudoplastic behavior well described by the Hershel–Bulkley model (R2 ≥ 0.975). Estimates of model parameters showed that the yield stress and consistency index ranged from 0.027 to 33.958 Pa and 4.614 to 41.313 Pasn, respectively. The flow behavior index, n (0.027 ≤ n ≤ 0.551), confirmed the pseudoplastic behavior of the sauces. Temperature had a statistically significant effect on the estimated model parameters (p

This work aims to study the effect of incorporation of garlic essential oil (GEO) with loading of 10% (GEO-10) and 20% (GEO-20) on the strength and stability of polyelectrolyte complex coacervate obtained by electrostatic interactions between chitosan (CH) and whey protein isolate (WPI) with positive and negative charges, respectively. Rheological studies were applied to investigate the viscosity and viscoelastic properties of complex coacervates. The viscoelastic properties were investigated by dynamic oscillatory tests and static tests (creep and recovery). The coacervates exhibited the shear-thinning behavior of non-Newtonian fluid, and the frequency sweep test revealed magnitude of elastic modulus (G′) higher than loss modulus (G″) at high frequency due to the formation of compact network structure with elastic dominant property (solid-like behavior). Arrhenius model was able to estimate the relationship between viscosity and temperature, and the high temperature caused molecular expansion and increase in intermolecular distances, leading to decrease on the viscosity. The energy of activation (Ea) was 25.24 and 20.74 kJ mol−1 for WPI/GEO-10/CH and WPI/GEO-20/CH, respectively. The highest Ea value for WPI/GEO-10/CH indicated the formation of more strength and structured network matrices for GEO protection. Creep and recovery data were well fitted by Burger model and exponential decay function, respectively, and obtaining R2 higher than 0.98. The percentage recovery (%R) was 16.67% and 9.52% for WPI/GEO-10/CH and WPI/GEO-20/CH, respectively, indicating that WPI/GEO-10/CH had greater capacity for structural recovery and the most suitable to be applied in food product that industrially requires large stress, high temperature and long-time processes.

Many research studies have been conducted on the ultraviolet (UV) ageing performance of asphalt and asphalt mixture, but the superposition relationship between the loading time–temperature and the ...

Cold in-place recycling (CIR) of asphalt pavements is a process that has successfully been used for many years. The use of CIR for rehabilitation offers many advantages over traditional overlays due to its excellent resistance to reflective cracking and its environmentally friendly impacts. Despite the good performance and positive sustainability aspects of CIR, the structural contribution of the CIR base layer has not been well defined. In this research, CIR mixtures were designed with different asphalt emulsions. The mixtures were then subjected to dynamic modulus, repeated load triaxial, and flexural beam fatigue testing over a range of temperature and loading conditions. The performance test data generated were then used to develop CIR rutting and fatigue performance models used in the mechanistic analysis of flexible pavements. The technique used to develop the performance models leveraged the fact that the rutting and fatigue models for individual CIR mixtures were all within the 95 percent confidence interval of each other. A mechanistic analysis was conducted using the 3D-Move Mechanistic Analysis model. With the laboratory-developed performance models, the structural layer coefficient for the CIR base layer were developed for use in the 1993 AASHTO Guide for the Design of Pavement Structures. This analysis led to the determination of an average structural coefficient of the CIR base layer of 0.25.

Hypothesis Relative to the bulk systems, the near-wall ( Experiments The combination of active microrheometry (multipole magnetic tweezers) and total internal reflection microscopy (TIRM) was employed to probe the structure–rheology relationships of microgel dispersions near a substrate surface. The ω, T, and ϕeff-dependences of the storage modulus (G′), loss modulus (G"), and softness (J) were analyzed by power-law and Arrhenius-like scaling theories. The fluctuation of J was further analyzed to give a quantitative description of the inhomogeneity in the near-wall regions. Findings (1) Remarkable differences in the rheological behaviors between the bulk and near-wall cases are revealed, where the latter shows a segmented overlap behavior in ϕeff; (2) Five regimes of ϕeff that correspond to distinct physical states of the microgel dispersions are determined; (3) The near-wall local structures exhibit more heterogeneity in the glass and colloidal gel regimes as compared to the liquid regime.

We perform immersed-boundary-method numerical simulations of small amplitude oscillatory shear flow of suspensions of monodisperse noncolloidal rigid spherical particles in non-Newtonian liquids from the dilute to the concentrated regime. We study the influence of suspending liquid inertia and rheology and particle concentration on the computationally measured storage and loss moduli of the suspensions. In particular, the rheology of the suspending liquid is modeled through the inelastic shear-thinning Carreau-Yasuda constitutive equation and the viscoelastic Giesekus and Oldroyd-B constitutive equations. The role of inertia is quantified by the Stokes number, St, whereas the relevance of the non-Newtonian effects of the suspension matrix is measured through the Carreau number, Cu, for the Carreau-Yasuda liquid and the Deborah number, De, for the viscoelastic liquids. In suspensions with a Carreau-Yasuda matrix, both the storage and the loss modulus increase with St and decrease with Cu, yet the order of magnitude of Cu has to be greater than unity for these effects to be visible. In suspensions with a viscoelastic matrix, both the moduli increase with St and have a nonmonotonic trend with De, showing a maximum with no quantitative differences between the results pertaining suspensions with Giesekus and Oldroyd-B constitutive equations.

To study the influence of basalt fibers on the viscoelastic mechanical properties of asphalt concrete (AC) mixtures, unconfined compressive dynamic modulus tests were performed on styrene–butadiene–styrene (SBS)-modified AC mixtures reinforced with various contents of basalt fibers ranging from 0.2 to 0.5% by weight at five temperatures and six load frequencies, and the dynamic moduli and phase angles of the mixtures were measured. Compared with the test results of the control mixture (with no basalt fibers), the data show that the high-temperature dynamic modulus of the mixtures initially increases and subsequently decreases with increasing fiber content and reaches its maximum value when the basalt fiber content is 0.3%, while the low-temperature dynamic modulus decreases monotonically with increasing fiber content. Furthermore, the phase angle of the mixtures initially decreases and later increases with increasing fiber content and reaches its minimum value when the basalt fiber content is 0.3%. These behaviors indicate that the addition of basalt fiber improves the high-temperature rutting resistance and low-temperature cracking resistance of the SBS-modified AC mixtures. In addition, the results of the wheel rut test exhibit a good correlation with the results of the dynamic modulus test, revealing the reliability of the dynamic modulus test for evaluating the high-temperature rutting resistance of basalt-fiber-reinforced AC mixtures.

Relevant mechanical parameters of asphalt composites, such as the dynamic modulus and phase angle, are obtained by means of four-point bending tests. It is a dynamic test based on the application of sinusoidal load pulses and sinusoidal displacement response. A sinusoidal response can be difficult to record due to different issues, such as noise during an experiment. In strain-controlled tests with the application of a low-load amplitude with asphalt mixtures at high temperatures composed with calcined clay, which is the case of the test carried out in this study, a relationship was observed between the apparent noise recorded and the frequencies of the beam’s natural vibration. This outcome led to the conclusion that these imperfections are not a result of failures in the procedure, but of the natural behavior of the beam. This conclusion can assist in the filtering of information to obtain better results.

This work aimed to use natural deep eutectic solvents to modify the thermal, textural, freeze-thaw, and rheological properties of high amylose rice starch. Three different natural deep eutectic solvents (NADES) composed of sugar and organic acids were applied to modify the properties of starch dispersion. In presence of NADES, the onset temperature of starch was decreased, in comparison with starch in aqueous and glycerol medium. During thermal decomposition, starch with the aqueous and glycerol systems showed two-step weight losses whereas with NADES starch showed single-stage weight losses or decomposition. Moreover, negligible syneresis was observed for starch-NADES dispersion after 3rd cycle of the freeze-thaw process. The flow behavior of starch-NADES dispersion follows Herschel–Bulkley models as R2 (0.996 ≤ R2 ≤ 0.999) are higher than the Mizrahi-Berk model. The flow behavior index (n) of starch-NADES dispersion was closer to 1, indicated a nearly Newtonian fluid. The loss modulus (G″) value of starch-NADES dispersions was markedly higher than the corresponding storage modulus (G′) value and thus materials behaved like viscoelastic liquid. The present study manifested a green way to modify the properties of the high amylose starch to improve the processing stability.

The viscoelasticity of Taxodium hybrid ‘Zhongshanshan’ wood, while undergoing hydrothermal processing, was investigated via dynamic thermomechanical analysis. The results showed that the elastic deformation and viscous deformation of the Taxodium hybrid ‘Zhongshanshan’ heartwood were greater than the sapwood. The heartwood average storage modulus and average loss modulus were greater than the sapwood. The difference between the heartwood and sapwood had little effect on the average glass transition temperature of their hemicellulose, which was approximately 74 °C. The radial average storage modulus was greater than the tangential, and the difference between the average loss modulus in the radial and tangential directions was negligible. The average glass transition temperature in the radial direction was slightly lower than the tangential direction. As the moisture content increased, the average storage modulus and its average hemicellulose glass transition temperature decreased. The average glass transition temperature tended to be lower as the moisture content increased. This study revealed the structural deformation and molecular movement of Taxodium hybrid ‘Zhongshanshan’ wood, while undergoing hydrothermal processing; this has important theoretical value for understanding its characteristics as well as its rational and efficient usage.

Made available in DSpace on 2022-04-28T19:43:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The dynamic mechanical behavior (storage modulus, loss modulus, and tan δ) of hybrid sisal/glass composites was investigated in the temperature range of 30–210 °C, for two different volume percentages of reinforcement along with the different ratios of sisal and glass fibers. Based on the experimental outcome, an artificial neural network (ANN) approach was used to predict the dynamic mechanical properties followed by a surface response methodology (SRM). The ANN analysis showed an excellent fit with the storage modulus, loss modulus, and tan δ experimental data. In addition, the fitted curves with the ANN approach were used to propose equations based on SRM. The simulation result has shown that the ANN is a potential mathematical tool for the structure–property correlation for polymer composites and may help researchers in the development and application of their data, reducing the need for long experimental campaigns. Federal University for Latin American Integration (UNILA) Department of Materials and Technology School of Engineering São Paulo State University (Unesp) Postgraduate Program in Mining Metallurgical and Materials Engineering (PPGE3M) Federal University of Rio Grande do Sul (UFRGS) Postgraduate Program in Engineering of Processes and Technologies (PGEPROTEC) University of Caxias do Sul (UCS) Department of Materials and Technology School of Engineering São Paulo State University (Unesp)

Made available in DSpace on 2022-04-28T19:40:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Thermoplastic starch (TPS) is a widely studied biopolymer as an alternative to the use of conventional polymers. In this sense, the incorporation of fillers or reinforcements coming preferably from other substances of natural origin, can be an alternative to try to improve some mechanical and thermal properties of starch polymers. Thus, Kraft Lignin (KL), can be an excellent filler to be incorporated, since it presents mechanical and thermal properties and reduces the cost and weight of the final compounds. TPS films were prepared by casting using dimethyl sulfoxide (DMSO) as solvent and additives with 2, 4 and 8% KL. Characterization of TPS films and compositions with KL were carried out by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), Dynamic Thermomechanical Analysis (DMTA), tensile testing and contact angle. Samples were also analyzed for biodegradation and for the ability to remove contaminants in water, Metil Orange (MO), by Ultraviolet-Visible Spectroscopy (UV–Vis). The FT-IR spectra of the films showed bands typical of functional groups derived from starch and lignin, with the intensity of these bands varying among the samples studied. Micrographs revealed slightly different morphologies among the films, but all showed irregular shapes with structures that appeared as plots. Increasing the percentage of KL led to an increase in contact angle values, showing a more hydrophobic behavior. In the TGA analysis, it was possible to observe a change in the main degradation event of the films for lower temperatures, especially of TPS – 4 and 8% KL compared to the TPS film. Films with KL had the peak of maximum degradation shifted to temperatures below the starch film, where the decrease in intensity of the main peak in the TPS - 4% KL and TPS - 8% KL samples demonstrates that there was less mass loss in the event. There was also in the percentage of residue as the addition of KL was increased The DMTA analyses allowed for the conclusion that presence of KL in TPS film allowed for an increase in its energy storage property, and that the loss modulus followed a decreasing order of storage modulus values to TPS - 8% KL from TPS. For the tensile strength property only TPS - 4% KL has significant improvement, and the elongation at break showed an increase for TPS – 4 and 8% KL compared to TPS. Samples showed a continuous and progressive biodegradation process, being completely biodegraded within 10 days. The monitoring of the ability to remove contaminants from water by UV–Vis, also showed promising results of compounds for this application. The best results were obtained, in most tests, for the TPS- 4% KL films. Polymers and Biopolymers Technology Laboratory (TecPBio) Institute of Science and Technology (ICT) Federal University of São Paulo (UNIFESP) Lignocellulosic Materials Laboratory Science and Technology Center for Sustainability (CCTS) Federal University of São Carlos (UFSCar), João Leme dos Santos, km 110 Science and Technology Institute of Sorocaba (ICTS) São Paulo State University (UNESP), Av. Três de Março, 511 Science and Technology Institute of Sorocaba (ICTS) São Paulo State University (UNESP), Av. Três de Março, 511 CAPES: 001 FAPESP: 2019/15976-0 FAPESP: 2019/19401-1 CNPq: 313989/2018-4

It is fundamentally important to investigate the interfacial friction between softened glass and rigid molds for controlling the product quality in glass hot forming techniques. However, the underlying mechanism has not been fully understood in terms of the contribution of viscous dissipation to the viscoelastic friction of softened glass. In this paper, a dry rotary sliding scheme using the ball-on-disc pair is employed to investigate the high-temperature friction characteristics of a typical borosilicate crown glass N-BK7 from 500 °C to 660 °C . Experimental results show that the friction coefficients in the steady stage remarkably increase with the applied temperatures. For softened glass, friction could originate from adhesion, ploughing and dissipation. Furthermore, with careful estimations on both the scratch deformation frequency and the induced flash temperature during sliding, the increase in friction coefficient with temperature is well correlated with the loss modulus ratio, which presents the viscous energy dissipation by macroscale ploughing. Additionally, the friction coefficients at 500 mm/s are slightly larger than those at 250 mm/s, because the effect of more frictional heat prevails. Lastly, the influences of temperature and frequency shifting on the loss modulus ratio are summarized to explain the experimental evolution of friction coefficient. It is confirmed for N-BK7 glass that the dependences of friction coefficients on temperature and sliding velocity, also follow the classical superposition master curve of viscoelastic friction.

The spent fluid catalytic cracking (SFCC), waste from the petroleum industry, is nonstop increasing and causing environmental pollution in Vietnam. This study is an attempt to recycle SFCC in pavement construction. The study investigated the effect of SFCC, as a filler material in the hot-mix asphalt (HMA), on the essential characteristics of the asphalt concrete mix. First, the optimum percentages of bitumen and SFCC rate were investigated based on the Marshall design method. The HMA with SFCC showed more enhanced stability, flow, and other Marshall properties than the asphalt concrete mixture with the optimum limestone filler of 5%. Besides, the effects of SFCC rates on Marshall characteristics were explored. Second, performance tests were conducted to compare the mix with the different optimum content fillers of SFCC, limestone, and Portland cement. The tests include wheel tracking, indirect tensile, fatigue, and dynamic modulus tests to evaluate the performance of HMA with SFCC. It was found that the asphalt mixture with the optimum SFCC filler content can enhance pavement performance and improve the rutting and cracking resistance of the asphalt pavement.

Resumen La modificación de mezclas asfálticas con polímeros de desecho brinda diversos beneficios. Entre los más importantes se encuentra la optimización del desempeño de la mezcla y el incremento en su vida útil. Esto sin considerar, una reducción en la cantidad de residuos plásticos que no poseen un adecuado manejo de desecho. El presente artículo muestra los resultados obtenidos de una investigación en donde se incorporó a una mezcla asfáltica un material de desecho tipo blíster (compuesto por polímeros como el PVC) por medio de la vía seca. Método en donde, previo a la adhesión del asfalto, se incorpora a la mezcla el modificante en sustitución de parte del agregado fino. Esto con el propósito de evaluar el desempeño de esta mezcla y comparar su comportamiento mecánico con el de una mezcla convencional. Para la ejecución del proyecto se caracterizó el modificante (blíster) y se seleccionó el porcentaje adecuado para que el diseño de la mezcla modificada cumpliera con las especificaciones de la metodología Superpave. Con el diseño definido se realizaron los especímenes de ensayo y se evaluó su desempeño con las pruebas de: fatiga a cuatro puntos, rueda de Hamburgo, resistencia retenida a la tensión diametral y módulo dinámico. Como se identificó un adecuado comportamiento de la mezcla modificada, se evaluó su sensibilidad en una estructura de pavimento; identificando en qué capas de la mezcla asfáltica sería conveniente utilizarla. Abstract The modification of asphalt mix with waste polymers provides several benefits. Among the most important is the optimization of the performance of the mix and the increase in its useful life. Not to mention a reduction in the amount of plastic waste that does not have an adequate waste management. This article shows the results obtained from a study where a blister type waste material (composed of polymers such as PVC) was incorporated into an asphalt mixture by the dry method. Method in which, prior to the asphalt adhesion, the modifier is incorporated to the mix in substitution of part of the fine aggregate. The purpose of the study was to evaluate the performance of the mix and compare its mechanical behavior with a conventional mix. For the project development, the modifier was characterized, and the appropriate percentage was selected so that the design of the modified mixture would comply with Superpave requirements. With the optimized design, the test specimens were prepared, and their performance was evaluated based on the following tests: four-point beam bending, Hamburg wheel, retained tensile strength (moisture damage) and dynamic modulus. Since an adequate behavior of the modified mix was observed, its sensitivity was evaluated in a pavement structure; identifying in which layers of the asphalt mix should the material be used.

The hot mix asphalt (HMA) dynamic modulus (∣E*∣), or stress/strain response measurement under dynamic loading, is considered the primary mechanical property input for flexible pavement in the Mechanistic-Empirical Pavement Design Guide (MEPDG). The current MEPDG software, AASHTOWare Pavement ME Design (PMED) Version 2.5, employs the Witczak equation for ∣E*∣ estimation when laboratory-measured ∣E*∣ data is unavailable. This study investigates the feasibility of developing alternative ∣E*∣ prediction models with modern machine learning techniques based on an established data library of Georgia HMA mixtures involving varying binder sources, binder grades, and nominal maximum aggregate sizes. Specifically, tree-based ensemble methods, including bagging, random forest, and gradient boosting, were applied considering their superior performance, and balanced versatility and interpretability. The results revealed that the gradient boosting model produced the most accurate predictions with an R2 coefficient of determination of 0.982 as compared to the nationally calibrated Witczak model, which has an R2 of 0.392, using the same test data set. The stark discrepancy in the ∣E*∣ predictions emphasizes the need of local calibration for the MEPDG models and the high potential for developing greatly improved models using modern machine learning techniques with the local data sources. Ultimately, this study provides an excellent example for other state highway agencies to follow to facilitate their MEPDG implementation.

The damping behavior of continuous SiC fiber reinforced aluminum matrix (SiCf/Al) composite is still poorly understood. This paper examined the temperature dependence and strain amplitude dependence of damping capacities in 30 vol% SiCf/Al composites including SiCf/2024Al, SiCf/6061Al and SiCf/AlFe5Si2 composites, and the unreinforced aluminum alloys. Microstructure characterization was performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscattered diffraction (EBSD) and X-ray diffraction (XRD) analysis to investigate the operative damping mechanisms in the SiCf/Al composites. The results show that uniform dispersion of SiCf and good interface bonding were achieved with these SiCf/Al composites. The damping capacity and dynamic modulus of these composites were greatly improved as compared with that of the unreinforced aluminum alloys. The dominant damping mechanisms for SiCf/Al composites were dislocation damping at low temperatures ( 150 ℃). This work indicated that the SiCf/AlFe5Si2 composite simultaneously exhibited good damping capacity and high dynamic modulus, having potential for aerospace applications.

In this study, the effect of curing applied to jute woven fabric (four-layers) reinforced composite materials in which different proportions of acrylated epoxidized soybean oil (AESO) and epoxy resin are used as matrix material, on the thermal, thermo-mechanical and morphological properties of the composite materials are investigated. Composite material production is carried out by vacuum infusion method, whereas curing at 90 °C is done during production and post-curing at 120 °C is performed using a conditioning oven after production. Dynamic mechanical analysis (DMA) results show that the storage and loss modulus values of composite materials increase with increasing AESO ratio, while tan delta curves display that the bonds between the fiber and matrix of hybrid samples are stronger than composite materials using a single type of resin. This result is also supported by scanning electron microscope (SEM) images. The effect of curing (90 °C) and post-curing (120 °C) temperatures on the thermo-mechanical properties of the composite material is more clearly seen in epoxy composite samples whose glass transition temperature is higher than the room temperature. Besides, the decrease in glass transition temperature of the material with the increase in AESO content is obtained from both DMA and differential scanning calorimetry (DSC) plots.

The effect of the reverse micelle extraction method (RMEM) on the physicochemical properties of soy 11S globulin was studied and compared with that of the traditional alkali solution-acid precipitation method (ASAPM). The results showed that the β-sheet structure content of soy 11S globulin obtained by RMEM was lower, while the β-turn structure content was higher compared with that obtained by ASAPM. Furthermore, the protein unfolding degree and surface hydrophobicity were lower than those observed using ASAPM. Therefore, RMEM better maintained the natural molecular structure of soy 11S globulin. The thermodynamic and rheological properties of soy 11S globulin obtained by these two methods were further compared, showing that the highest denaturation temperature and transition heat of soy 11S globulin extracted using ASAPM were different from those obtained using RMEM. Furthermore, soy 11S globulin extracted by RMEM showed stronger heat resistance and a higher denaturation temperature than that extracted by ASAPM. The final storage modulus and frequency sweep results showed that the gel formed by soy 11S globulin obtained using RMEM had high storage modulus and loss modulus. PRACTICAL APPLICATION: In this study, the effects of two different extraction methods on structural and functional properties of soy 11S globulin, such as thermodynamics and rheology, were investigated. We can know the 11S globulin extracted using the reverse micelle environment was more heat-resistant and heat-induced gel quality of 11S globulin was improved by the reverse micelle environment. These results will provide theoretical basis that would help determine the potential applications of soy 11S globulin in the food system.

Biodegradable poly(propylene carbonate) (PPC)/epoxidized soybean oil (ESO) blends with different component ratios were prepared by melt blending to improve the performance of PPC. The phase morphology, thermal properties, rheological properties and mechanical properties of the blends were investigated in detail. SEM examination revealed good interfacial adhesion between PPC matrix and ESO. According to DSC and DMA, as the content of ESO increased, the glass transition temperature of the PPC component increased, indicating that there was a strong interfacial interaction between the PPC matrix and ESO. The interfacial interaction may be caused by ring-opening reaction between the hydroxyl end groups of PPC and the epoxy groups of ESO, which restricted the chain movement of PPC matrix. The disappearance of the epoxy groups in FTIR indicated that the interfacial interaction between the two phases was due to the ring-opening reaction between PPC and ESO. With the addition of ESO, the thermal stabilities were enhanced. With the increasing ESO content, the modulus gradually decreased. However, the strength at yield, the strength at break and the elongation at break were increased for the PPC/ESO blends, suggesting that the enhancement of the strength and toughness of PPC was achieved by the incorporation of ESO. The rheological measurement revealed that the complex viscosity, storage modulus and loss modulus of PPC were increased with the increasing ESO content at low frequency, which indicated that the addition of ESO enhanced the melt strength of PPC instead of plasticizing PPC.

Rutting resistance is an important consideration for paving asphalt mixes. The cause of rutting is a shear strain in the asphalt pavement structure. Here, the rutting behavior of asphalt pavements was evaluated through laboratory simulations using the Hamburg Wheel-Tracking Test (HWTT), UK Wheel-Tracking Test (UKWTT), and Scaled Accelerated Load Simulator (SALS) test. The correlation between the three simulation tests was analyzed to determine the conversion factor (CF). Two parameters of temperature and speed of simulation testing were evaluated in this study. Subsequently, the representative frequency and dynamic modulus were calculated with consideration of viscoelasticity and time–temperature superposition. Using logical analysis, CF between the three simulation tests was validated. The results showed that the full-scale test yielded the highest stiffness modulus of 4,015 MPa, and the UKWTT yielded the lowest stiffness modulus of 1,857 MPa at 60 °C. From the HWTT results, it was found that the impact of moisture damage at 40 °C is not substantial compared to that at 50 °C. The conversion factor of HWTT at 40 °C, HWTT at 50 °C and UKWTT at 60 °C to SALS were 0.92, 0.74, and 0.63, respectively. Furthermore, the similar rutting performance among SALS, HWTT at 40 °C in dry and wet conditions, and HWTT at 50 °C in dry condition can be observed when the CF is applied. Lastly, the effectiveness of the conversion factor is diminished with increasing rutting damage.