Strain Sweep Tests Research Articles

Rapid Synthesis of Self‐Healing, pH‐Responsive IA‐Based Hydrogels via Frontal Polymerization

ABSTRACTSelf‐healing polymeric gels have emerged as a promising class of materials due to their ability to repair damage autonomously, offering significant advantages for various applications. Nevertheless, a major hurdle to their widespread practical use lies in their often‐compromised mechanical strength and long reaction time. Herein, we present the synthesis of a new type of self‐healing hydrogels using poly(itaconic acid‐co‐hydroxypropyl alcohol‐co‐acrylic acid), also known as poly(IA‐co‐HPA‐co‐AAc), by a frontal polymerization (FP) method. The rapid reaction rate of FP facilitates the swift and energy‐efficient synthesis of the hydrogels within 10 min, eliminating the need for prolonged reaction times. Additionally, the results revealed that the synthesized hydrogels exhibited pH‐dependent responsiveness, robust mechanical integrity, and autonomous self‐healing capabilities, obviating the requirement for external stimuli. The exceptional self‐healing properties can be attributed to the extensive hydrogen bonding network between the polymer chains, enabling them to recover up to 80% of their original mechanical strength. Rheological analysis confirmed the presence of a robust and stable gel network, evidenced by high storage modulus (G′) values across the entire frequency and strain sweep tests. This research addresses a significant knowledge gap in IA‐based hydrogels by introducing a rapid, optimized method for constructing self‐healing materials through hydrogen bonding interactions.

Early-age structural build-up and rheological assessment of alkali-activated slag-red clay brick waste pastes: Influence of silica modulus and precursors proportions

Sustainability plays a crucial role in the current context of the cement industry, and alkali-activated materials (AAMs) are emerging as eco-efficient alternative binders. On the other hand, the massive generation of red brick waste worldwide and its lack of a defined destination emphasizes this material as an alternative precursor that has been insufficiently explored in the literature. Based on this context, the present study aims to investigate the structural build-up, reaction kinetics, and rheological properties of alkali-activated pastes based on blast furnace slag (BFS) and red clay brick waste (RBCW). Fresh properties such as structural build-up, rheology, and reaction kinetics are lacking in the literature on RCBW-based AAMs, highlighting these properties as a research gap to be filled and discussed in depth in this paper. The flow sweep test was performed, linked to yield stress and viscosity properties. The structural build-up was evaluated by strain sweep and small amplitude oscillatory shear (SAOS) tests based on viscoelastic parameters: storage modulus, loss modulus, and phase angle. Isothermal calorimetry and in-situ FTIR were also conducted to complement the analysis and provide insight into the reaction kinetics, chemical structure, and product formation. Higher silica modulus (Ms) resulted in a lower structural build-up rate and a delayed reaction. Higher content of RCBW resulted in a delayed structuration process, which was linked to a delay in the precipitation of aluminosilicate gels. Early increase in the structural build-up in 25 % and 50 % RCBW blends (Ms = 1.0) is associated with the early formation of a well-percolated network.

Evaluation of the synergistic effect of nanocomposite hydrogel based on imidazolium nitrate ionic liquids for enhanced oil recovery

A comprehensive research study was conducted to examine the synergistic properties of ionic liquids, and hydrogels. Two nanocomposite hydrogel samples were created: one with ionic liquid and the other without. The samples were made using hydrogel with acrylamide (AM) backbone, Al2O3 nanoparticles, and ionic liquid [C8mim][NO3]. The effectiveness of a nanocomposite hydrogel containing an ionic liquid was tested to improve the wettability alteration and sweeping efficiency of reservoirs. Various tests were performed including IFT, electroconductivity, micromodel, SEM, and equilibrium swelling tests. The tests showed that the presence of the ionic liquid increased the swelling up to 102 %. IL increased conductivity by 124.24 % and 44.86 % at ambient temperature and 90 °C respectively. In the strain sweep test, the maximum elastic modulus for NCH-IL was recorded as 40,350 Pa, while for the sample without ionic liquid, it was 27,100 Pa. The frequency sweep test confirmed the three-dimensional structure of the gel. IL increased the maximum elastic modulus from 13,200 Pa to 27,400 Pa. The critical frequency value also increased by 87.5 %. Moreover, the suspension, which contains 1 wt% of Nanocomposite Hydrogel based on Imidazolium Nitrate Ionic Liquids, has shear-thinning properties, making it easy to inject into reservoirs. The reduction of the contact angle from 109° to 14.2° demonstrated the ability of IL to alter the wettability of NCHs. This result stemmed from the release of part of the ionic liquid within the hydrogel structure, as confirmed by the UV test. During the emulsion stability test, it was observed that the NCH-IL sample created a stable emulsion and a more complete two-phase separation than the sample without the ionic liquid. The sample that contained IL recorded 85 % and 78.4 % oil recovery in homogeneous and heterogeneous micromodels, respectively. Whereas, the sample without IL recorded 71.27 % and 60.73 % in the same micromodels.

A new synergistic hydrocolloid with superior rheology: Locust bean /xanthan gum binary solution powdered by different drying methods

In the current study, a novel gum powder containing locust bean and xanthan gums was prepared by three different drying methods of their synergistic aqueous solutions: direct cabinet drying (CD), drying after alcohol precipitation (PD), and direct freeze drying (FD). The purpose of this process is to develop ready-to-use synergistic gum powders with improved rheological properties by modifying intermolecular interactions. Significant improvements in viscosity, consistency efficiency and pseudoplastic character were observed for PD, followed by CD and FD, as well as the higher values of G′ and G″ values of PD, indicating a stronger entanglement network development between the macromolecules for PD. PD exhibited better elasticity and shear resistance compared to FD and CD in the strain sweep test. In Lissajous curves, straight line shapes were found for synergistic solutions at low strain, which continued for increasing strain values for PD and CD. However, the pronounced viscous behavior was found for FD at 500% strain. Compared to CD and FD, PD exhibited a more desirable thixotropic character. A lower zeta potential was observed in the production of synergistic gums using the PD process. Gel strength was found to be higher for PD. Therefore, PD was a more effective method to produce a ready-to-use synergistic powder with better viscoelastic properties and a more stable solution.

Effects of non-linearity and thixotropy in linear amplitude sweep testing for the evaluation of self-healing of bituminous binders

Linear amplitude sweep tests have been demonstrated to have good potential in being used for the evaluation of self-healing properties of neat and polymer-modified bituminous binders. Past research works, however, have neglected the effects of material non-linearity and thixotropy. This implies that the whole material integrity loss is attributed to damage and all restoration to self-healing, thus resulting in the possible overestimate of both damage and self-healing when evaluating the fatigue performance of materials. In the study described in this paper, specific experimental and analytical methods were adopted with the purpose of separating non-linearity and thixotropy in LAS healing tests. Non-linearity was assessed by means of multiple strain sweep tests carried out to determine the material non-linear viscoelastic moduli at specific testing temperatures. Thixotropy was considered by coupling self-healing LAS testing with a purposely defined test in which loading was applied to the undamaged material after a rest period equal to that applied in self-healing tests. Obtained results were processed by means of an analytical approach based on the simplified viscoelastic continuum damage model. Quantification of self-healing included the determination of material integrity and damage parameters recovered after the rest period. Such parameters, calculated by excluding time-dependent and non-linear biasing effects, can be used as straightforward indicators of the self-healing potential of neat and polymer-modified bituminous binders. Moreover, obtained results substantiate the concept that time–temperature superposition is still applicable when non-linearity is incorporated into the simplified viscoelastic continuum damage model.

Evaluation of a Strain Sweep Tests Protocol as a Tool for Assessing the Homogeneity of SBR Copolymer Composition

Global competition in products and services demands constant improvement in production systems. Similarly, it is essential for industries to have quality control tools capable of assessing the compliance of a given product at a lower cost and with greater effectiveness. In the rubber and composite industry, where complex formulation and mixing systems can affect not only the quality of the final product but also the processing of rubber, the development of a protocol that assumes this function is important. The present study developed samples of elastomeric blends based on styrene-butadiene copolymer (SBR) with different filler concentrations (30, 60, and 90 phr of ground tire rubber as filler), which were analyzed using an oscillating cavity rheometer (MDpt-TechPro). Based on a proprietary testing protocol, the degree of homogeneity of the composites was evaluated, which was compared with scanning electron microscopy studies. The implemented protocol, which provides results within 30 minutes, proved to be promising for quality control of these blends, and it can be used by rubber processing industries, saving both time and cost, being an unprecedented study on the 'homogeneity-rheology' relationship.

The Effect of Glucose Syrup on Rheological Properties of Sago Starch

The effect of glucose syrup on the rheological properties of sago starch was examined. The glucose syrup (30 - 75 g) was mixed with sago starch 100 g and baked at 60 °C for 16 h. The sago starch formulas 1 - 10 were analyzed rheological properties using a strain sweep test for evaluated Linear Viscoelastic Range (LVR) used for studied temperature test and frequency test. The result showed that the G’ values of the sago starch formulas 1 - 10 decreased respectively which indicated an increase in the amount of glucose syrup resulting in the storage modulus within the starch structure decreasing causing agglomeration. In addition, in the temperature range of 70 - 95 °C, the sago starch formula 1 - 10 began to gelatinize and then stabilize. It indicated that the sago starch slurry was more similar to the solid. When the temperature was lowered from 95 to 30 °C, the G’ and G” values of the sago starch formulas 1 - 10 gradually increased and then decreased because the starch solution during heating is agglomerated into large particles. The flexibility of solids within the powdery structure is very high and very viscous, so that during the initial decrease in temperature, the G’ and G” values increase. After a while, when the temperature inside the structure begins to decrease, which causes the value of G’ and G” to decrease. In the analysis of texture characteristics of the sago starch formulas 1 - 10, it was found that Hardness, Gumminess and Chewiness decreased significantly as the ratio of glucose syrup was increased in the formulations of the sago starch. The lower hardness value of the sago starch formulation with more added content of glucose syrup. Adhesiveness, cohesiveness and springiness values were not different between all the sago starch formulations. HIGHLIGHTS Rheological properties of the sago starch formulas showed that more glucose syrup mixed with sago starch, increased viscoelastic behavior because when increasing the frequency, there will be a value G' > G'' The different textures of the sago starch formulations indicated the basic action of glucose syrup on the microstructure of the sago starch The differences in rheological properties and texture of the sago starch formulas are the reasons for choosing different filling ratios of sago starch and glucose syrup for cooking GRAPHICAL ABSTRACT

Rheological properties of porcine organs: measurements and fractional viscoelastic model.

The rheological properties of porcine heart, kidney, liver and brain were measured using dynamic oscillatory shear tests over a range of frequencies and shear strains. Frequency sweep tests were performed from 0.1Hz to a maximum of 9.5Hz at a shear strain of 0.1%, and strain sweep tests were carried out from 0.01% to 10% at 1Hz. The effect of pre-compression of samples up to 10% axial strain was considered. The experimental measurements were fit to a Semi-Fractional Kelvin Voight (S-FKV) model. The model was then used to predict the stress relaxation in response to a step strain of 0.1%. The prediction was compared to experimental relaxation data for the porcine organ samples, and the results agreed to within 30%. In conclusion, this study measured the rheological properties of porcine organs and used a fractional viscoelastic model to describe the response in frequency and time domain.

Characterization of novel alginate-Aloe Vera raft systems for treatment of gastroesophageal reflux disease

Raft-forming systems are designed to relieve reflux symptoms by forming a physical barrier on top of the stomach. The present study aimed to evaluate the physico-chemical properties of alginate-aloe vera raft-forming systems for the first time. To achieve this goal, aloe vera was used in the proportion of 1 and 1.5 % in raft suspensions containing 5 % alginate as the main component of gel structure. Rafts were characterized by their volume, floating behavior, thickness, swelling properties, strength, resilience, reflux resistance, and acid neutralization capacity (ANC). Results showed the effectiveness of aloe vera in forming rafts that were voluminous, buoyant with greater total floating time (TFT), and stronger than formulations with no aloe vera. Furthermore, data showed that the presence of aloe vera could improve resilience time, swelling proportions, resistance to reflux under simulant conditions of movement in the stomach, and ANC values of rafts. Rafts were further characterized by oscillatory strain sweep test, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Evaluation of the mechanical properties of rafts displayed a viscoelastic behavior of gels corresponding to the internal cross-linked structure of rafts. This study demonstrated that designing of alginate-aloe vera rafts can be suitable for the treatment of gastro-esophageal reflux disorders.

From waste to value: Characterization of recycled cellulose acetate for sustainable waste management

Cellulose acetate (CA) is a versatile polymer with various industrial applications, but its recycling process is still far from diffuse adoption. In this study, the purification of CA was confirmed through FTIR analysis, which exhibited characteristic peaks corresponding to cellulose molecules and acetylation. The rheological behavior of regenerated CA demonstrated shear thinning properties, making it suitable for applications requiring viscosity reduction under shear. Oscillation strain and frequency sweep tests revealed the formation of a gel-like network structure in CA solutions due to extensive hydrogen-bonding networks between water and acetone. The evaporation kinetics of acetone from CA films were found to be temperature and thickness-dependent, exhibiting both Fickian and non-Fickian diffusion mechanisms. The diffusion coefficient of acetone in CA films was determined and correlated with film porosity. Mechanical testing indicated comparable strain at rupture and ultimate strength between recycled and commercial CA, while a limited reduction was observed for the elastic modulus. These findings suggest potential applications of recycled CA in packaging and textile sectors, highlighting the importance of further research in optimizing its properties for specific industry requirements.

Effect of gamma irradiation on structural properties and rheological behavior of binary biopolymer blend: A case study on guar gum-sage seed gum blends

In this study, different gum powders (guar gum (GG), sage seed gum (SSG) and guar-sage seed gums (GG-SSG) were irradiated at 0, 5, and 10 kGy. FTIR analysis revealed some small changes in transmittance of gum samples with gamma irradiation. Flow behavior of the gum solutions (1% w/w) revealed shear thinning behavior with a n value lower than 1. The viscosity of gum solutions (1% w/w) decreased significantly with increase of irradiation dose from 0 to 10 kGy which was in consistent with the effect of irradiation dose on the consistency index (k). Herschel–Bulkley and Sisko models with higher values of determination coefficient (R2) were found to be the best models to explain the steady shear properties of non-irradiated and irradiated gum solutions. Irradiation doses (5 and 10 kGy) changed the flow behavior of guar gum solution (1%) from non-Newtonian shear-thinning to Newtonian behavior. G’ and G’’ in GG, SSG, and GG-SSG were observed to decrease in strain sweep test as the irradiation dose was increased from 0 to 10 kGy. In SSG and GG-SSG, G’ was greater than G’’ with no cross over in all the applied frequency range, while guar gum exhibited a solid-like behavior after cross over point. Frequency sweep rheological parameters of gum solutions (1%) including G’, G’’, and (η*) also affected by gamma irradiation and decreased significantly with increasing irradiation dose from 0 to 10 kGy (p<0.05).

The effect of filler content on mechanical properties and cell response of elastomeric PGS/apatite foam scaffolds

Poly(glycerol sebacate) (PGS) is a novel polymeric material intended for applications in tissue engineering (TE). This study involves synthesizing the PGS prepolymer (pPGS) and subsequent manufacturing of porous PGS-based scaffolds with an addition of hydroxyapatite (HAp) by means of thermally induced phase separation followed by thermal cross-linking and salt-leaching (TIPS-TCL-SL). The study aims to investigate the effect of the apatite filler content on properties and morphology of porous PGS/HAp scaffolds. The emphasis is put on the mechanical behavior of the material characterized by means of compression tests and dynamic thermal mechanical analysis (DMTA). In addition to the reference polymer scaffold, the composites with filler contents of 10, 20 and 30 wt% have been examined. Our research revealed that the HAp content does not affect the mechanical properties in a directly proportional manner. The 30 wt% addition of HAp resulted in frayed structure and decrease in the mechanical parameters in comparison to other tested specimens. On the other hand, an addition of 10% did not sufficiently boost the properties. Therefore, a 20% addition of HAp was concluded to have superior mechanical properties in comparison to other analyzed specimens. A similar relationship results from the DMTA studies. Moreover, the strain sweep and frequency sweep tests confirmed the stability of the mechanical parameters in various conditions, as well as the elastomeric nature of the materials. Finally, the material did not exhibit cytotoxicity against standard L929 fibroblasts and cells readily populated the scaffolds.

Structural build-up and breakdown of alkali-activated slag pastes with different order of lignosulfonate and activator addition

One of the crucial issues of alkali-activated materials is the application of conventional plasticizers. Lignosulfonate plasticizer (LS) works well for sodium hydroxide-activated slag but loses its efficiency in sodium waterglass-activated slag because of competitive adsorption with silicates. Therefore, the effects of the timing of LS and activator addition on the structural build-up and breakdown of AAS pastes with low-silicate moduli activator (0 to 0.50) were investigated, particularly by means of non-traditional strain sweep tests, which are thoroughly discussed. The rheological tests were correlated with the Vicat needle test and isothermal calorimetry. The results showed the high efficiency of LS in NaOH-activated slag paste over time, regardless of the order of addition of the components of the paste. It was accompanied by a considerable retardation effect of LS on the hydration of AAS. The beneficial effect of LS on the rheological parameters and hydration kinetics decreased rapidly with an increase of the silicate modulus of the activator. The delayed addition of the concentrated silicate-containing activators completely counteracted the slightly beneficial effect of LS and even accelerated the initial structural build-up.

Design and fabrication of a Preformed Thixotropic-Viscoelastic Nanocomposite hydrogel system (PNCH) for controlling sand production in reservoirs

In this study, the performance of preformed dual crosslinked nanocomposite hydrogels (PNCH) consisting of acrylamide, 2-acrylamide-2-methylpropane sulfonic acid, maleic acid, and acrylic acid in sand control was investigated. Also, the effects of three nanoparticles (NPs) of iron (PNCH1), silicon (PNCH2), and bentonite (PNCH3) on the PNCH structure were studied. The morphology, equilibrium swelling ratio (ESR), rheology, thermal strength, zeta potential, and compressive strength were experimentally analyzed. According to the XRD results, the NPs were completely dispersed in all three samples. The results of SEM and EDS tests confirmed the presence of NPs within the PNCHs with a dense, homogeneous, and porous structure. The results of the ESR at distilled and formation water at ambient temperature for PNCHs (1), (2), and (3) were (13.9,4.55), (15.45, 6.35), and (12.9, 4.8), also at reservoir temperatures ESR results were reported (78, 17.5), (89, 13), and (70,12.9) respectively. From the TGA results, structure destruction of PNCHs starts at 222, 225, and 202 °C respectively so the addition of 1 wt% of NPs increased the structure destruction from nearly 80 °C to more than 200 °C. Based on the results of the strain sweep test, structures of PNCHs can cause viscoelastic behavior with the maximum elastic modulus of 29,000, 8430, and 10,800, and critical strain of (10%, 19.3%, and 10.8%) respectively. The loop test results confirmed the time-dependent viscoelastic properties of thixotropic in all structures. Finally, in compressive strength test revealed that adding 0.5 pore volume of 1 wt% of PNCH into the sandpack increased its strength by 980%.

Investigating the Performance of Co [AM-AMPS-MALEIC-AAC]/ PEI-MBA Nanocomposite Hydrogel in Sand Control from Oil Reservoirs

Sand production is one of the major challenges in oil and gas production from sandstone reservoirs. Production losses, formation damage, corrosion, and equipment failure are all consequences of sand production. Various mechanical and chemical methods are used to control sand production. One of the most efficient chemical methods is the injection of hydrogels, but its application has been constrained by the hydrogels' weak stability in the harsh conditions of the reservoir. A Co [AMAMPS-MALEIC-AAC]/PEI-MBA nanocomposite hydrogel with superior viscoelastic properties and double crosslinking was developed and synthesized to overcome these restrictions. Swelling, rheology, and morphology tests were utilized to predict the produced nanocomposite's effectiveness and performance in the harsh Iranian reservoirs. According to the obtained results, at ambient temperature (25°C, during injection) and reservoir temperature (90°C, placed in a porous medium), in distilled water, the maximum swelling ratio was 8.5 and 94, and in formation water, the maximum swelling ratio was 5.4 and 10.8, respectively. The X-ray diffraction test findings show that the nanoparticles are uniformly distributed throughout the structure. Also, according to the results of the thermal strength test, the sample’s thermal stability up to 90°C was confirmed with less than 0.6 wt% degradation. The results of the strain sweep, frequency sweep and stress-strain tests demonstrate the existence of a robust, three-dimensional, and viscoelastic structure up to a strain of 100% and a frequency of 100 Hz. In the strain sweep test with a constant frequency of 1 Hz, the maximum storage modulus was reported as 27,000 Pa, and in the frequency sweep test with a constant strain of 1%, 18,000 Pascals were reported. The stress-strain test revealed that the ultimate tensile strength of the synthesized material was 4630 pascals. These characteristics make the aforementioned nanocomposite hydrogel ideal for usage in porous media.

Chitosan Hydrogels Cross-Linked with Trimesic Acid for the Delivery of 5-Fluorouracil in Cancer Therapy.

Chitosan exhibits unique properties making it a suitable material for drug delivery. Considering the rising popularity of hydrogels in this field, this work offers a comprehensive study of hydrogels constituted by chitosan and cross-linked with 1,3,5-benzene tricarboxylic acid (BTC; also known as trimesic acid). Hydrogels were prepared by cross-linking chitosan with BTC in different concentrations. The nature of the gels was studied through oscillatory amplitude strain and frequency sweep tests within the linear viscoelastic region (LVE) limit. The flow curves of the gels revealed shear thinning behavior. High G' values imply strong cross-linking with improved stability. The rheological tests revealed that the strength of the hydrogel network increased with the cross-linking degree. Hardness, cohesiveness, adhesiveness, compressibility, and elasticity of the gels were determined using a texture analyzer. The scanning electron microscopy (SEM) data of the cross-linked hydrogels showed distinctive pores with a pore size increasing according to increasing concentrations (pore size range between 3-18 µm). Computational analysis was performed by docking simulations between chitosan and BTC. Drug release studies employing 5-fluorouracil (5-FU) yielded a more sustained release profile with 35 to 50% release among the formulations studied in a 3 h period. Overall, this work demonstrated that the presence of BTC as cross-linker leads to satisfactory mechanical properties of the chitosan hydrogel, suggesting potential applications in the sustained release of cancer therapeutics.

Evaluation of the effects of asphalt binder aging degree on the curing, compatibility, and mechanical behaviors of epoxy asphalt binders

The application of epoxy asphalt binder in hot mix plant recycling for reclaimed asphalt pavement (RAP) can significantly increase the utilization rate of waste material on the premise of ensuring the service quality of the asphalt pavement. However, the development of epoxy asphalt binder modified RAP is hindered by the limited understanding of the effect of aging degree and types variability of asphalt binder in RAP on the properties of epoxy asphalt binder. Therefore, short-, long- and ultra-long- term aging tests of base asphalt and SBS modified asphalt binder were conducted through rolling thin film oven (RTFO), pressure aging vessel (20 h and 40 h) tests to obtain the asphalt binders with different aging extent, and then the binders were mixed with two epoxy systems to prepare epoxy asphalt binders, respectively. Next, the effects of asphalt binders aging degree on curing, compatibility, and mechanical behaviors characteristics of epoxy asphalt binders were investigated from chemical, microscopic, mechanical, and rheological perspectives based on Brookfield viscosity, Fourier transform infrared (FTIR), laser confocal fluorescence microscopy (LSCM), Shore hardness, direct tensile, strain sweep, and frequency sweep tests. The viscosity results indicated that a higher asphalt binder aging degree brought about a faster increase in the viscosity of epoxy asphalt binders. The construction allowable time of type-A epoxy asphalt binder of at least 3.5 h was higher than that of type-B. The conversion degree model constructed with the 917 cm−1 peak area as a parameter showed that the epoxy asphalt binder prepared by the asphalt binder with a more severe aging degree presented a higher conversion degree within the same curing time since the reaction space between epoxy and curing agent reactive groups was compressed by aggregated aged asphalt binder. The LSCM and Shore hardness results suggested that the aging asphalt binders induced the phase separation between asphalt and epoxy resin. With the asphalt binders aging, the distribution of asphalt phase in the epoxy system changed from black dots (12–15 um) to island-shaped structures (50–98 um), and eventually transferred a neuron-shaped network structure to connect island-shaped synaptosomes to block the continuity of three-dimensional network structure of epoxy resin. The rheological tests showed that the linear viscoelastic (LEV) region of the epoxy asphalt binders changed with the asphalt binders aging degree, and a shear strain of 0.01% ensured that specimens was within the LEV region. The effects of asphalt binders aging degree on the complex modulus and phase angle master curves of type-A epoxy asphalt binders mainly reflected the low frequency region (10−4 to 10−1 Hz), while the effects on type-B epoxy asphalt binders were in the whole frequency range (10−4 to 103 Hz).

A framework for the analysis of damage and healing viscoelastic behaviour of asphalt binders

This paper aims to develop a framework for characterizing damage and healing viscoelastic behaviour of asphalt binders. The framework is based on modifying the 2S2P1D (two springs, two parabolic elements, and one dashpot) viscoelastic model such that the evolution of the exponent ‘k’ of the parabolic creep function is associated with damage and healing behaviours. The model efficacy is corroborated through the analysis of viscoelastic response, damage, and healing of four asphalt binders (i.e. one unmodified asphalt and three other asphalts modified using low-density polyethylene and various additives.) These binders were subjected to strain sweep tests to determine their linear viscoelastic strain limit. In addition, frequency sweep tests at several temperatures were conducted to obtain binder linear viscoelastic parameters. Then, the binders were subjected to strain-controlled, cyclic progressive damage tests (continuous loading) as well as cyclic damage-healing tests (i.e. cyclic loading with rest periods). The test data were analysed to obtain the storage and loss moduli as functions of loading cycles, and they were modelled using the modified version of the 2S2P1D model. The exponent of the parabolic creep element ‘k’ was formulated using a hyperbolic cosine function that quantifies the deviation from the linear viscoelastic response during damage and healing. The results showed that the ‘k’ function was suitable to quantify the damage and healing responses of the asphalt binders at the test conditions. Furthermore, the parameters in the ‘k’ hyperbolic cosine function were used to create a plot for classifying binders based on their damage and healing characteristics.

3D printing surimi enhanced by surface crosslinking based on dry-spraying transglutaminase, and its application in dysphagia diets

Dry-spraying transglutaminase (TG) was explored as surface modification agent for enhancing the surimi structures and promoting its practical 3D printing application. Glycerol functionalization, 3D extruding critical parameters, TG based surface crosslinking, practical cooking loss, and innovative applications of 3D-printed surimi were investigated. Rheological performances (shear ramp, strain sweep and thixotropy tests) indicate that glycerol could enhance excellent pseudo plasticity (fluid behavior index n < 1), high mechanical strength & strain resistance (high G′, and wide linear viscoelastic region 2.51%), and outstanding thixotropy (high recovery rates, up to 61.47%) of surimi, owing to that glycerol could promote the hydration of surimi myosin and prevent protein aggregation by stabilizing aggregation-prone intermediates. The further optimization of the extruding parameters (nozzle diameter 1.00 mm and “Rectilinear” filling structure) would improve the surimi dimensional printing deviations, and increase surimi gel strength (up to 22.29 g mm) by regulating interlayer bonding zones. Compared with chemical crosslinking agents NaCl and CaCl2 for modifying surimi, surface crosslinking based on dry-spraying TG would better raise the printable height efficiency (97.50%), improve the surimi texture, and enhance suitable water distribution, resulting in fine and dense network by hydrophobic interactions, disulfide bonds and non-disulfide covalent bonds. Subsequently, the cooking loss tests and International Dysphagia Diet Standardization Initiative tests proved that 3D-printed surimi could be classified as a potential transitional food for dysphagia groups. Surface crosslinking based on dry-spraying TG suggests a bright promise in practical high-accuracy, sophisticated 3D printing of surimi and holds potential in dysphagia diets and innovating food products.

Application of high-intensity ultrasound to modify the rheological properties of a guamuchil Pithecellobium dulce (Roxb.) seed protein isolate

ABSTRACT In the present study, the application of high-intensity ultrasound (USon) on the rheological properties of guamuchil seed protein isolate (GPI) was evaluated. GPI dispersions (30% w/v) were subjected to USon treatments (20 kHz; 200, 400, and 600 W) for 15 and 30 min. Strain, frequency, and temperature sweep tests showed that the storage (G) and loss (G”) moduli increased, while loss tangent (Tan δ) decreased by USon. The results showed a dominance of G’ over G”, indicating the formation of a stronger and more elastic dispersion due to USon, especially at high power (600 W for 15 and 30 min). Compared to native GPI, the USon treatments that caused the largest decreases in apparent viscosity (ηapp ) and the most notable shear thinning behavior were at low (200 W) and high (600 W) power. The modification of the rheological characteristics of GPI by USon could be associated with structural changes, which modifies the inter and intramolecular interactions. The rheologically improved GPI by USon could represent an alternative to diversify its possible use as a new food ingredient.