Rheological Properties Research Articles

Effects of γ-polyglutamic acid on the rheological, microstructural and sensory properties of low-fat yogurt.

While low-fat yogurt offers numerous health benefits, its texture and sensory qualities are poor. This study aimed to investigate the effects of γ-polyglutamic acid (γ-PGA) on the rheological, microstructural and sensory properties of low-fat yogurt using rheological tests, scanning electron microscopy (SEM) and sensory evaluation. The results showed that the syneresis of low-fat yogurt added with 0.15% γ-PGA was significantly (P < 0.05) reduced to 23.03%, compared to that of low-fat yogurt without γ-PGA (42.87%). An improvement in storage and loss moduli (G', G") and apparent viscosity was also observed. The power law model fitted to rheological data indicated that γ-PGA enhanced the viscoelasticity and strength of the gel network though interaction with casein gel, which might lead to changes in the moduli of yogurts. Microstructural observation via SEM confirmed the enhanced crosslinking between casein micelles and the filling effect of γ-PGA. Sensory liking scores were strongly correlated with rheological properties and apparent viscosity. The results of principal component analysis (PCA) confirmed the positive effects of γ-PGA on quality and rheological attributes of low-fat yogurt. The results of this study provided valuable references for the potential use of γ-PGA as a fat replacer to stabilize the sensory quality of low-fat yogurt. © 2024 Society of Chemical Industry.

Evaluation of long-term effects of isothermal conditioning of binders recovered and stabilised from bitumen emulsion

ABSTRACT Cold recycling technology is gaining popularity as an economically and environmentally beneficial alternative to Hot Mix Asphalt (HMA). The cohesion of cold recycling mixtures (CRMs) containing bitumen emulsion (BE) is provided by residual bitumen due to the emulsion breaking process at ambient temperatures. The influence of CRM and HMA production operations on the ageing behaviour of bituminous binders needs further investigation. In this study, the basic, rheological, and chemical properties of binders recovered and stabilised (STAB) from unmodified and SBS-modified cationic BEs were investigated and compared to the properties of the unaged and short-term aged (RTFOT) base binders. Dynamic Shear Rheometer (DSR) tests were performed to examine the impact of the recovery, stabilisation, and RTFOT ageing in the initial testing phase and after long-term isothermal conditioning, simulating base course conditions. To quantify these effects, the Ageing (AI) and Conditioning (CI) indexes were introduced, respectively. The results showed that in the initial testing stage, the STAB binders exhibited intermediate basic and rheological properties between unaged and RTFOT-aged ones. Yet, statistical analysis has proven that the applied long-term conditioning significantly influenced the dynamics of change in the complex shear modulus (G*) of STAB and RTFOT binders. FTIR spectroscopy results confirmed this observation.

Tailoring the Properties of 2D Nanomaterial‐Polymer Composites for Electromagnetic Interference Shielding and Energy Storage by 3D Printing—A Review

3D‐printed 2D nanomaterials‐based polymer composites, with their exceptional electrical conductivity and structural functionalities, have become leading‐edge engineering materials for electromagnetic interference (EMI) shielding, sensors, and energy storage applications. This review begins with a brief introduction to various types of 2D nanomaterials and their fabrication techniques, specifically different types of 3D printing. The subsequent sections highlight key factors such as rheological properties, surface tension, additives, and binders that influence the printability of 2D nanomaterials‐based polymer composites. The advancements in 2D nanomaterials‐based polymers, including MXene, graphene, and graphene derivatives, are then presented. The interaction, dispersion, and/or network formation of 2D nanomaterials in the polymer matrix is a crucial factor in determining the electrical performance of the composites. This review also discusses surface modification strategies for 2D nanomaterials to enhance their sensing, EMI shielding, and energy storage capabilities. Finally, the impact of various 3D‐printed polymer composite geometries, such as rectangular, cylinder, and circular, on shielding performance is thoroughly examined, engaging the reader in the exploration of these materials.

INFLUENCE OF HUMIC ACIDS ON RHEOLOGICAL PROPERTIES OF COMPOSITE SUSPENSIONS BASED ON PYROCARBON

The possibility of utilizing technical pyrocarbon obtained as a result of pyrolysis of waste tires into composite suspension fuel was investigated. It was determined that the surface of unmodified pyrocarbon has a positive surface charge in the pH range of 2-10. The addition of humic acid causes a change in the surface charge of pyrocarbon and an overcharge of the surface. The influence of stabilizer additives on the rheological properties of composite suspension fuel based on pyrocarbon was studied. Carboxymethyl cellulose, OP-10, and humic acids were used as stabilizers. It is shown that the composite suspension fuel based on pyrocarbon has a synergistic effect of the addition of OP-10 with sodium humate to reduce the effective viscosity and fluidity of suspensions. A composite suspension fuel consisting of [0.5% C3 + 0.25% OP + 3% HA] at a solid phase concentration of 51.7% was proposed. The effective viscosity of the obtained suspensions does not exceed 0.9 Pa‧sec, and the sedimentation stability is 28-30 days. This allows us to recommend the obtained suspensions as liquid suspension fuel for liquid fuel units.

Rheological, Thermal, and Textural Characteristics of White, Milk, Dark, and Ruby Chocolate

This study compares the rheological, thermal, and textural characteristics of four types of chocolate—white, milk, ruby, and dark—produced by the same manufacturer. White, milk, and ruby chocolates contain 36% fat, while dark chocolate has 39%. Cocoa content varies from 28% in white, 33% in milk, 47% in ruby, to 70% in dark chocolate. Rheological properties were assessed with a rotational rheometer, while density was measured with a gas pycnometer. Particle size distribution (PSD) was evaluated using laser diffraction, and thermal properties were analyzed with differential scanning calorimetry (DSC). The DSC results indicated that enthalpy increased with cocoa content, whereby dark chocolate showed the highest value (55.04 J g−1) and white chocolate the lowest (35.3 J g−1). PSD followed a monomodal pattern; dark chocolate had the smallest particles, leading to the highest hardness. Density ranged from 1.2773 to 1.2067 g∙cm−3. The results from classical rotational rheological measurements were in accordance with oscillatory measurements. Rheological measurements confirmed that the Casson yield stress was the highest for milk chocolate (17.61 Pa). The viscosity values decreased with increasing shear rate for all chocolates. All chocolate samples showed strong shear-thinning behavior up to a 100 s−1 shear rate. Oscillatory measurements showed the paste-like nature of all samples, i.e., storage modulus G’ dominates loss modulus G’’ at small shear stress values, and the complex modulus G*, which represents the stiffness, varied as follows: milk &gt; white &gt; dark &gt; ruby. This study offers valuable insights into the properties of chocolates during production and storage, helping manufacturers anticipate key characteristics for new confectionery products.

Enhanced Stability and Properties of Benzene-1,3,5-Tricarboxamide Supramolecular Copolymers through Engineered Coupled Equilibria.

Improving the stability of multi-component and functional assemblies such as supramolecular copolymers without impeding their dynamicity is key for their implementation as innovative materials. Up to now, this has been achieved by a trial-and-error approach, requiring the time-consuming characterization of a series of supramolecular coassemblies. We report herein that this is possible to significantly enhance the stability of supramolecular copolymers by a minimal change in the chemical nature of one of the interacting monomers. This is achieved by replacing an ester function by an ether function in the structure of a chiral benzene-1,3,5-tricarboxamide (BTA) monomer, used as "sergeant", coassembled with achiral monomers, the "soldiers". Pseudo-phase diagrams, constructed by probing the nature of the coassemblies with multifarious analytical techniques, confirm that the greater stability of the resulting copolymers is mainly due to the minimization of competing species. This leads to better rheological and catalytic properties of the corresponding supramolecular copolymers. Favouring coassembly over undesired assembly pathways must be considered as a blueprint for the development of better-performing supramolecular multi-component systems.

Enhanced Stability and Properties of Benzene‐1,3,5‐Tricarboxamide Supramolecular Copolymers through Engineered Coupled Equilibria**

AbstractImproving the stability of multi‐component and functional assemblies such as supramolecular copolymers without impeding their dynamicity is key for their implementation as innovative materials. Up to now, this has been achieved by a trial‐and‐error approach, requiring the time‐consuming characterization of a series of supramolecular coassemblies. We report herein that this is possible to significantly enhance the stability of supramolecular copolymers by a minimal change in the chemical nature of one of the interacting monomers. This is achieved by replacing an ester function by an ether function in the structure of a chiral benzene‐1,3,5‐tricarboxamide (BTA) monomer, used as “sergeant”, coassembled with achiral monomers, the “soldiers”. Pseudo‐phase diagrams, constructed by probing the nature of the coassemblies with multifarious analytical techniques, confirm that the greater stability of the resulting copolymers is mainly due to the minimization of competing species. This leads to better rheological and catalytic properties of the corresponding supramolecular copolymers. Favouring coassembly over undesired assembly pathways must be considered as a blueprint for the development of better‐performing supramolecular multi‐component systems.

Performance Assessment of Eco-Friendly Asphalt Binders Using Natural Asphalt and Waste Engine Oil

The depletion of petroleum reserves and increasing environmental concerns have driven the development of eco-friendly asphalt binders. This research investigates the performance of natural asphalt (NA) modified with waste engine oil (WEO) as a sustainable alternative to conventional petroleum asphalt (PA). The study examines NA modified with 10%, 20%, and 30% WEO by the weight of asphalt to identify an optimal blend ratio that enhances the binder’s flexibility and workability while maintaining high-temperature stability. Comprehensive testing was conducted, including penetration, softening point, viscosity, ductility, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results reveal that WEO effectively softens NA, improves ductility, and enhances workability, with the 20% WEO blend achieving the best balance of physical and rheological properties. Chemical analysis indicates that WEO increases carbon content and reduces sulfur and impurities, aligning NA’s composition closer to PA. However, excessive WEO (30%) compromises thermal stability and deformation resistance. The findings underscore the potential of WEO-modified NA for sustainable pavement applications, with 20% WEO identified as the optimal content to achieve performance comparable to conventional petroleum asphalt while promoting environmental sustainability.

Effect of Malvaviscus arboreus Flower and Leaf Extract on the Functional, Antioxidant, Rheological, Textural, and Sensory Properties of Goat Yogurt

The present study aimed to evaluate the effects of incorporating different concentrations (1% and 2%) of Malvaviscus arboreus flower (FE) and leaf (LE) extracts as functional ingredients in goat milk yogurt. This study analyzed the impact of these formulations (YFE1%, YFE2%, YLE1%, and YLE2%) on the physicochemical, bioactive, antioxidant, rheological, textural, and sensory properties of goat yogurt over a 28-day storage period. Including FE and LE extracts significantly enhanced the yogurt’s antioxidant activity, reaching up to 10.17 µmol TEAC/g, and strengthened its ability to inhibit lipid oxidation during storage. This study also observed a reduction in the viability of lactic acid bacteria, particularly L. delbrueckii subsp. bulgaricus, suggesting that the extracts may have antimicrobial properties. Notably, using FE, especially at a concentration of 2% (YFE2%), improved both antioxidant and textural properties while reducing syneresis by the end of the storage period. Sensory evaluations showed positive results for YFE1% and YFE2% formulations. These findings suggest that FE has significant potential as a functional food ingredient. This research lays the groundwork for future studies exploring the integration of Malvaviscus arboreus-based ingredients into functional food products, opening new possibilities for innovation in this field.

Influence of natural oils on the textural and rheological properties of cosmetic creams

Creams are semisolid dosage forms widely used for pharmaceutical and cosmetic purposes due to their pleasant appearance, easy spreadability, and the possibility to deliver hydrophobic and hydrophilic active agents. The aim of the current study was to evaluate the impact of type and concentration of different oil phases on the mechanical and rheological properties of cosmetic creams. For this purpose, a series of blank and anti-age creams were prepared applying the hot homogenization method (9000 rpm for 5 minutes). The blank creams contained an emulsifying base (Neofin Nat 8% w/w) and varying types of lipid phase: 1) babassu oil (8% w/w), 2) Cannabis sativa (2% w/w) and Camelina sativa (6% w/w) oils, 3) babassu (6% w/w) and Cannabis sativa (2% w/w) oils, and 4) babassu (6% w/w) and Camelina sativa (2% w/w) oils. The anti-age creams contained additionally Jasminum sambac flower extract (5% w/w) and Аrgireline® solution (5% w/w). The spreading, mechanical, and rheological properties of the developed formulations were investigated. The anti-age cream based on babassu (6% w/w) and Camelina sativa (2% w/w) oils exhibited suitable textural and rheological characteristics that would facilitate its application onto skin and provide sufficient contact time to exert its beneficial effects.

Impact of solar exposure on chemical and rheological properties of hybrid polymer modified bitumen with recycled plastics

This study examines the effects of summer solar exposure in Casablanca, Morocco, on the chemical and rheological properties of virgin bitumen and hybrid Polymer-Modified Bitumen (PMB) incorporating Recycled Low-Density Polyethylene (R LDPE) and Recycled Polypropylene (R PP) with Styrene-Butadiene-Styrene (SBS) copolymer, with and without Sulphur. Hybrid PMB formulations were prepared by adding 4% SBS and other additives to base bitumen. Ultraviolet (UV) aging, rheological tests, Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared Spectroscopy (FTIR) were conducted to analyze aging mechanisms and performance. Results demonstrate that hybrid PMB modified with R LDPE and R PP shows superior aging resistance compared to SBS-PMB, while the addition of Sulphur further enhances durability. These findings highlight the potential of recycled polymers and Sulphur in improving bitumen performance under solar exposure.

Prediction of the rheological properties of mortar compounded with desert sand and Pisha sandstone ceramic sand based on density-form coupling

Ordos, China has a large amount of environmentally hazardous Pisha sandstone and desert sand. Pisha sandstone ceramic sand and desert sand can be compounded to prepare light and fine aggregates, which are often used in construction mortar. However, it is unknown how the density and particle shapes of light and fine aggregates affect their rheological properties. In this study, we establish a predictive model for the rheological properties of light and fine aggregate mortar, using the Krieger-Dougherty and Chateau-Ovarlez-Trung models as a basis. First, density and particle morphology parameters are introduced and modified for light and fine aggregate mortars. Then, the morphological parameters of different types of fine aggregate particles were measured using image analysis techniques. This showed that the roundness of the particles decreases with decreasing density, and both the roughness and the aspect ratio increase. A regression model between the particle morphology parameters and characteristic viscosity was accordingly developed. The rheological properties of different types of mortars were examined. We find that as the particle density decreases, the yield stress and plastic viscosity decrease continuously, showing shear thickening behavior. Based on the coupled density-form effect, a modified Krieger-Dougherty model and Chateau-Ovarlez-Trung model are proposed. These proposed models result in more accurate predictions of plastic viscosity and yield stress for light and fine aggregate mortars.

Upcycling of Postconsumer PET Using Serinol: Green Preparation of a New Multifunctional Initiator for PLA

ABSTRACTChemical recycling is attracting more and more interest as it can transform a plastic scrap into a high‐value material. This work shows that the aminolysis of postconsumer poly(ethyleneterephthalate) (PET) with serinol, a nontoxic and biosourced hydroxyamine, leads to a novel multifunctional initiator for poly(lactic acid) (PLA). The reaction was performed at 180°C, without the need of catalysts, and resulted in a substantially complete aminolysis of PET, selectively yielding the corresponding diamide of terephthalic acid (terephthalic acid serinol bis‐amide, TASBA), together with ethylene glycol as the co‐product. TASBA holds four hydroxy groups and was used as multifunctional initiator in the polymerization of lactide to PLA, with 0.1%, 0.5%, and 1% w/w of TASBA with respect to L‐lactide. TASBA led to a multiarm PLA, whose molecular weight and thermal and rheological properties could be tuned with the amount of initiator. The lowest amount of initiator left substantially unaffected the molecular weight and led to higher melt viscosity and to lower crystallinity. Lower molecular weight and melt viscosity were obtained by increasing the amount of TASBA. This work therefore proposes a synergy between the most important polyesters, the most diffused PET and the compostable PLA.

Advancing self-compacting concrete performance with the use of combined marble waste as fine and coarse aggregates

Environmental protection through waste recycling is one of the major challenges of our time. Inert waste, mainly generated by industry, makes up a significant portion that harms the environment due to its accumulation in nature.The primary objective of this study is to examine the influence of marble waste valorization as sand and gravel on the rheological and mechanical properties of self-compacting concrete (SCC). For this study, marble was used as fine aggregate sand (MAS) at rates of 10%, 20%, and 30%, and as coarse aggregate gravel (MAG) at a rate of 100%. The results of this study demonstrate that the introduction of marble waste (MW) as aggregate positively influenced the rheological characteristics, notably reducing the need for superplasticizer dosage. Additionally, in terms of mechanical outcomes, the use of MAG led to improved mechanical strengths.

Rheological properties and 3D printability of SBS/CR-modified asphalt binder with C9 petroleum resin for crack filling

IntroductionThis study investigates rheological behavior and 3D printability of SBS-, CR-, SBS/CR-modified asphalt binder with C9 petroleum resin (C9PR) for crack filling.MethodsThirteen types of modified asphalt binders with respective C9PR of 0 wt%, 1 wt%, 2 wt%, 3 wt% were prepared and evaluated for their microstructure, physical properties, compatibility, rheological properties, and 3D printability.ResultsThe results show that SBS, CR, and C9PR influenced significantly on rheological properties and 3D printability of modified asphalt binders. Physical blending and improved storage stability of modified asphalt binders were observed with the addition of C9PR. In addition, the combination of SBS and CR showed enhanced viscoelastic behavior and temperature sensitivity compared to the base asphalt binder due to the increased swelling behavior of SBS and CR in asphalt binders by C9PR.DiscussionAsphalt binder with 3 wt% SBS, 15 wt% CR, and 1 wt% C9PR showed improved viscosity, elasticity, compatibility, high-temperature rutting resistance, and fatigue resistance. Additionally, C9PR expanded 3D printable temperature range of modified asphalt binder, leading to its potential use as an additive in 3D printed asphalt binders.

Rheological, Fresh State, and Strength Characteristics of Alkali-Activated Mortars Incorporating MgO and Carbon Nanoparticles

This study presents a comprehensive assessment of the fresh state, rheological, and mechanical properties of alkali-activated mortars (AAMs) developed by incorporating magnesium oxide (MgO) and nanomaterials. A total of 24 AAM mixes with varying content of MgO, multi-walled carbon nanotube (MWCNT), and reduced graphene oxide (rGO) were developed following the one-part dry mix technique using powder-based activators/reagents. The effects of the types/combinations of source materials (binary or ternary)/reagents, MgO (0 to 5%), MWCNT (0 to 0.6%), and rGO (0 to 0.6%) were evaluated in terms of the mini-slump flow, setting times, viscosity, yield stress, compressive strength, ultrasonic pulse velocity (UPV), and microstructural properties. The results showed that the addition of finer MgO/nano-fillers produced a higher viscosity and yield stress accompanied by a lower slump flow and setting times. The addition of 5% MgO resulted in the lowest slump flow of 80 mm, 2–2.5 times higher viscosity, and the reduction in the initial and final setting times of about 21% and 16%, respectively. Mixes with MWCNT showed about 5–10% higher viscosity whereas for mixes with rGO, the values were noted to be 8% higher, on average, than the mixes with no MWCNT or rGO. All the developed AAMs exhibited shear-thinning behavior. The 28-day compressive strength of the AAMs ranged from 37 MPa to 49 MPa with 5% MgO and up to a 0.3% MWCNT/rGO addition increased the compressive strength. Correlations among the fresh state, rheological, and mechanical properties such as the viscosity, slump flow, setting time, compressive strength, and UPV are also described.

Preparation of PBAT/PLA Blend Microporous Foam With Excellent Resilience and Cushioning Properties by scCO2 Technology Through Improving Compatibility

ABSTRACTThe lightweight microcellular foams of polybutylene adipate terephthalate/polylactic acid (PBAT/PLA) with high mechanical strength and excellent resilience and buffering properties were reported using supercritical CO2 foaming technology. The effects of an epoxy chain extender (ST‐CE37B) on the mechanical properties, rheological properties, and dispersion morphology of PBAT/PLA blends were studied. The results showed that ST‐CE37B can act as compatibilizers and the PBAT/PLA blend with 0.5 phr ST‐CE37B exhibited the highest tensile strength (22 MPa). The PBAT/PLA foam with 0.7 phr ST‐CE37B, expansion ratio of 8.0 displayed the minor cell diameter (19.3 μm) and highest cell density (5.44 × 107 cells/cm3), the compressive strength was greater than that of pure PBAT/PLA foam, and the permanent strain was less than 15%. Therefore, compared with other foams, it can withstand larger stress according to the cushioning performance. In addition, this work also discussed the compression rebound performance (resilience) test of foam with the same blending sample, the same cell density, and different cell structures. It was found that foam with a larger cell size (49.2 μ m) showed lower permanent deformation and energy loss coefficient. This study provides a feasible method for preparing high microporous PBAT/PLA foam, expands the application range of biodegradable foam, and has research significance.

Tuning the rheological and mechanical properties of biodegradable PHBH/PLA/PVAc ternary blends via PVAc content control

Tuning the rheological and mechanical properties of biodegradable PHBH/PLA/PVAc ternary blends via PVAc content control

Production of Functional White Bread Enriched with Various Dietary Fibers with High Consumer Acceptance.

Fiber-enriched breads are inferior to wheat flour (white) breads in terms of volume, taste, and textural characteristics. The aim of this study was to produce functional dietary fiber (DF)-enriched white bread (WB) with high consumer acceptance. Wheat fiber (WF) was added to wheat flour as an insoluble fiber source (5%); polydextrose and inulin were used as soluble fibers at three different concentrations (2, 4, and 6%) individually or in combination. Their effects on dough rheology (farinograph and extensograph properties) and bread properties (volume, baking loss, moisture, texture, color, sensory, and crumb-grain characteristics) were investigated. The addition of WF, polydextrose and inulin had significant effects on dough rheology and bread properties. Hardness, chewiness, cell density, and DF content of breads were generally increased, whereas volume yield, baking loss, moisture and porosity values decreased with increasing DF concentration. The bread with the highest DF content (PD6IN6) contained 7.1 times more DF than WB. According to the results of sensory analysis, except for the sample with 6% concentration of polydextrose and inulin, all the other breads had very high overall acceptance values. Although the breads produced in the study have a high fiber content, their important quality characteristics (moisture content, volume yield, cell density, color values and sensory properties) are similar to those of WB. As a result, the overall quality characteristics of bread made with different dietary fibers were maintained, and functional WB enriched with DF were produced with high consumer acceptance.

Rheo-SINDy: Finding a constitutive model from rheological data for complex fluids using sparse identification for nonlinear dynamics

Rheology plays a pivotal role in understanding the flow behavior of fluids by discovering governing equations that relate deformation and stress, known as constitutive equations. Despite the importance of these equations, current methods for deriving them lack a systematic methodology, often relying on sense of physics and incurring substantial costs. To overcome this problem, we propose a novel method named Rheo-SINDy, which employs the sparse identification of nonlinear dynamics (SINDy) algorithm for discovering constitutive models from rheological data. Rheo-SINDy was applied to five distinct scenarios, four with well-established constitutive equations, and one without predefined equations. Our results demonstrate that Rheo-SINDy successfully identified accurate models for the known constitutive equations and derived physically plausible approximate models for the scenario without established equations. Notably, the identified approximate models can accurately reproduce nonlinear shear rheological properties, especially at steady state, including shear thinning. These findings validate the availability of Rheo-SINDy in handling data complexities and underscore its potential for advancing the development of data-driven approaches in rheology. Nevertheless, further refinement of learning strategies is essential for enhancing robustness to fully account for the complexities of real-world rheological data.