Drop In Viscosity Research Articles

Mechanical Performance of Recycled Reinforced Polyamide from Rejected Railway Fastenings Flanged Plates.

The superstructure of modern railway lines uses tons of technical polymeric material spread along the track with mechanical, insulating and damping functions. Many of these parts are rejected because they do not pass the quality controls, generating a large accumulation of plastic waste of high economic value. Therefore, this study is aimed at determining the optimum degree of recyclability by mechanical crushing of geometrically defective (and so rejected) railway fastenings flanged plates injected with short fiberglass-reinforced polyamide. After recycling, the material must guarantee its physical and mechanical properties required to ensure the future in-service conditions of the highly responsible components that guarantee the maintenance of the railway gauge. Viscosity, mechanical properties (tensile test), Charpy and fracture toughness as well as fatigue performance were determined for ten successive recyclings. It has been found that the drop of viscosity is the most restrictive limitation, allowing three recyclings of the material. All the properties measured have experienced a noticeable reduction after 10 recyclings. Specifically, viscosity is reduced by 15%, ultimate strength by 70%, yield stress by 41% strain under maximum load lost by 70%, Young's modulus lost by 38%, Charpy impact strength by 70%, fatigue resistance by 69% and fracture toughness lost by 80%. With the development of this study and taking into account that the market price of the flanged plates is valued at approximately 8 k€/km, of which around 5 k€/km corresponds to the raw material, the recovery of this material not only represents a great environmental benefit but also an economic one.

Tailoring and Long-Term Preservation of the Properties of PLA Composites with "Green" Plasticizers.

Concerning new polylactide (PLA) applications, the study investigates the toughening of PLA-CaSO4 β-anhydrite II (AII) composites with bio-sourced tributyl citrate (TBC). The effects of 5-20 wt.% TBC were evaluated in terms of morphology, mechanical and thermal properties, focusing on the enhancement of PLA crystallization and modification of glass transition temperature (Tg). Due to the strong plasticizing effects of TBC (even at 10%), the plasticized composites are characterized by significant decrease of Tg and rigidity, increase of ductility and impact resistance. Correlated with the amounts of plasticizer, a dramatic drop in melt viscosity is also revealed. Therefore, for applications requiring increased viscosity and enhanced melt strength (extrusion, thermoforming), the reactive modification, with up to 1% epoxy functional styrene-acrylic oligomers, was explored to enhance their rheology. Moreover, larger quantities of products were obtained by reactive extrusion (REX) and characterized to evidence their lower stiffness, enhanced ductility, and toughness. In current prospects, selected samples were tested for the extrusion of tubes (straws) and films. The migration of plasticizer was not noted (at 10% TBC), whereas the mechanical and thermal characterizations of films after two years of aging evidenced a surprising preservation of properties.

Towards commonality between shear banding and glass-liquid transition in metallic glasses

Despite the high attendance of shear banding in metallic glasses and other disordered materials, the nature of the emergence of shear band is still mysterious. Using molecular dynamics simulations, a set of detailed characterizations of shear band in a typical ${\mathrm{Cu}}_{50}{\mathrm{Zr}}_{50}$ metallic glass is obtained. Then we uncover a large number of robust and intriguing commonalities between the emergence of shear bands and the glass-to-liquid transition, including strong similarities on viscosity drop, enthalpy discontinuity, breakdown of hard backbone network, as well as relaxation process. Such observations indicate that shear banding in metallic glasses is a consequence of deformation-controlled glass transition, as further quantitatively validated via the compelling overlap between the venerable Vogel-Fulcher-Tammann law (and Adam-Gibbs relation) and the evolving glass state of shear band controlled by configurational temperature. These results provide a direct bridge between shear banding and glass-to-liquid transition and are instrumental to build the unified framework of flow behavior induced either by thermal or stressed stimuli in disordered materials.

Synthesis of High Injection Molding Performance and Low Acetaldehyde Poly(Ethylene Terephthalate) by Eco-Friendly and Highly Active Titanium Catalyst

In this paper, ECO-friendly titanium magnesium catalyst with high activity was synthesized, and titanium based bottle polyester was synthesized on a 30,000 ton annual industrial plant. At the same time, the characterization and processing properties of titanium based and antimony based polyester were studied. Compared with commercial antimony based polyester, TMPC chips had faster SSP rate and lower AA content, easier crystallization and high catalyst activity, easy to form macromolecular chains, and the rheology of polyester melt also showed a wider processing range. However, the chain end thermal degradation reaction of titanium based bottle chips was slightly larger than that of antimony based bottle chips, and the α transition temperature in DMA test also led to the molecular chain motion of titanium bottle chips is more easily affected by temperature, which was not conducive to maintaining a better viscosity drop and AA value of bottle preform for a long time in the high-temperature injection molding process. To sum up, according to the performance test results, by using TMPC catalyst and adjusting the processing conditions to control the injection molding process of TMPC polyester, titanium bottle preform with better viscosity drop and AA content can be obtained. Finally, the bottle preform with a weight of 28.5g was prepared by using titanium TMPC bottle chips. The injection molding processing temperature was reduced by 10 °C, the viscosity drop was equivalent to that of commercial antimony bottle preform, the end carboxyl group was reduced by 54%, the color index b value was reduced by 17.3%, and the AA content was reduced by 19.8%.

Smoothly adapting viscosity to velocity during comanipulation pointing movements

PurposeWhen a robot comanipulates an object with a human user, damping is a useful function. This is achieved by programming the robot to exhibit a viscous field. For some specific applications, the viscosity is required to change according to the manipulation velocity. A reported method is programming the viscosity varying inversely to the velocity. In this paper, this method is experimentally shown to distort human’s natural motion performance. This paper aims to propose a solution to solve this instability problem.Design/methodology/approachThe authors performed a point-to-point targeting movement, where it was observed that the instability results from a sudden reduction of robot’s resistance to motion, which further results from the abrupt viscosity drop when the subject tries to accelerate. Therefore, the authors propose a solution where a first-order linear filter is added to the viscosity coefficient so as to slow down its variation.FindingsThe experimental results confirm that the proposition is effective, with the ability to stabilize the comanipulated dynamics and to restore the human’s natural behavior.Originality/valueThis paper concerns applications of comanipulation where the viscosity coefficient is designed to decrease as the velocity increases. An instability problem, which was of vital importance in terms of safety and performance but unreported in the literature, was experimentally studied through human–robot experiments. A solution was proposed by including a secondary dynamics in the variations of the viscosity. Its effectiveness was supported by the practical point-to-point motion experiments.

A Novel ZnO Nanoparticles Enhanced Surfactant Based Viscoelastic Fluid Systems for Fracturing under High Temperature and High Shear Rate Conditions: Synthesis, Rheometric Analysis, and Fluid Model Derivation.

Surfactant-based viscoelastic (SBVE) fluids are innovative nonpolymeric non-newtonian fluid compositions that have recently gained much attention from the oil industry. SBVE can replace traditional polymeric fracturing fluid composition by mitigating problems arising during and after hydraulic fracturing operations are performed. In this study, SBVE fluid systems which are entangled with worm-like micellar solutions of cationic surfactant: cetrimonium bromide or CTAB and counterion inorganic sodium nitrate salt are synthesized. The salt reagent concentration is optimized by comparing the rheological characteristics of different concentration fluids at 25 °C. The study aims to mitigate the primary issue concerning these SBVE fluids: significant drop in viscosity at high temperature and high shear rate (HTHS) conditions. Hence, the authors synthesized a modified viscoelastic fluid system using ZnO nanoparticle (NPs) additives with a hypothesis of getting fluids with improved rheology. The rheology of optimum fluids of both categories: with (0.6 M NaNO3 concentration fluid) and without (0.8 M NaNO3 concentration fluid) ZnO NPs additives were compared for a range of shear rates from 1 to 500 Sec−1 at different temperatures from 25 °C to 75 °C to visualize modifications in viscosity values after the addition of NPs additives. The rheology in terms of viscosity was higher for the fluid with 1% dispersed ZnO NPs additives at all temperatures for the entire range of shear rate values. Additionally, rheological correlation function models were derived for the synthesized fluids using statistical analysis methods. Subsequently, Herschel–Bulkley models were developed for optimum fluids depending on rheological correlation models. In the last section of the study, the pressure-drop estimation method is described using given group equations for laminar flow in a pipe depending on Herschel–Bulkley-model parameters have been identified for optimum fluids are consistency, flow index and yield stress values.

Controlled Delivery and Photopatterning of Mechanical Properties in Polysaccharide Hydrogels Using Vanadium Coordination and Photochemistry.

Incorporation of the transition metal ion V(V) into hydrogels has been used to impart photoresponsive behavior, which was used to tune materials properties during light irradiation. The photoreaction in QHE-cellulose/agarose hydrogels coordinated with vanadium was evidenced by a clear color change of yellow to blue through a green intermediate. This color change was attributed to the reduction of V(V) to V(IV) as described in our previous work. A concomitant oxidative breakdown of the polysaccharide chain was noticeable upon the reduction of V(V) with a decrease in stiffness (G') of the hydrogel material. This reduction of the metal ion and breakdown of polysaccharide chain induced irreversible changes in the microstructure of the hydrogel, enabling the controlled delivery of V(IV) and/or encapsulated cargo. Scanning electron microscopy studies showed an increase in pore sizes and guest cavity formation during irradiation. In addition to the significant drop in mechanical properties like storage and loss modulus in the gel materials, a viscosity drop in the polymer solution was observed through irradiation, indicating breakdown of the polysaccharide chain. A photomask can be used to create discrete patterns on these materials upon irradiation.

An Extended Unified Viscoelastic Model for Predicting Polymer Apparent Viscosity at Different Shear Rates

Summary Polymer flooding is one of the most commonly used chemical enhanced oil recovery (EOR) methods. Conventionally, this technique was believed to improve macroscopic sweep efficiency by sweeping only bypassed oil. Nevertheless, recently it has been found that polymers exhibiting viscoelastic behavior in the porous medium can also improve microscopic displacement efficiency resulting in higher additional oil recovery. Therefore, an accurate prediction of the complex rheological response of polymers in porous media is crucial to obtain a proper estimation of incremental oil to polymer flooding. In this paper, a novel viscoelastic model is proposed to comprehensively analyze the polymer rheological behavior in porous media. This proposed model was developed and validated using 30 coreflooding tests obtained from the literature and further verified against a few existing viscoelastic models. The proposed viscoelastic model is considered an extension of the unified apparent viscosity model provided in the literature and is termed as extended unified viscoelastic model (E-UVM). The main advantage of the proposed model is its ability to capture the polymer mechanical degradation at ultimate shear rates primarily observed near wellbores. Moreover, the fitting parameters used in the model were correlated to rock and polymer properties using machine learning technique, significantly reducing the need for time-consuming coreflooding tests for future polymer screening works. Furthermore, the E-UVM was implemented in MATLAB Reservoir Simulation Toolbox (MRST) and verified against the original shear model existing in the simulator. It is worth mentioning that the irreversible viscosity drop for mechanical degradation regime was captured during implementing our model in the simulator. It was found that implementing the E-UVM in MRST for polymer non-Newtonian behavior might be more practical than the original method. In addition, the comparison between various viscosity models proposed earlier and E-UVM in the reservoir simulator showed that the latter model could yield more reliable oil recovery predictions as the apparent viscosity is modeled properly in the mechanical degradation regime, unlike UVM or Carreau models. This study presents a novel viscoelastic model that is more comprehensive and representative as opposed to other models in the literature. Furthermore, the need to conduct an extensive coreflooding experiment can be reduced by virtue of developed correlations that may be used to estimate model fitting parameters accounting for shear-thickening and mechanical degradation.

Hydrodynamics and Scaling Laws of Gas–Liquid Taylor Flow in Viscous Liquids in a Microchannel

The hydrodynamics of gas–liquid Taylor flow in microchannels is vital to the microreactor’s application, but its characteristics in viscous liquids are rarely reported. Accordingly, this study concentrates on the characteristics of bubble behavior in viscous liquids (45.6–240.5 mPa·s). The results show that the viscosity effect could dominate the bubble morphology. Importantly, considering the liquid film distribution, a novel parameter as the equivalent liquid film thickness is proposed for the square microchannel and it is strongly related to the capillary number and gas–liquid flow rate ratio. Besides, the bubble velocity first decreases to a minimum value and then becomes faster with the flow rate of the liquid, and the ideality of the multiphase system decreases with the increase of liquid viscosity and pressure drop. Finally, the viscosity term is introduced to the pressure drop equation based on the Lockhart–Martinelli type. This work enriches the understanding of the viscosity effect on gas–liquid microflows.

Azobenzene Based Photo-Responsive Hydrogel: Synthesis, Self-Assembly, and Antimicrobial Activity.

A new azobenzene-based symmetric amphiphile was synthesized and characterized using 1H NMR spectroscopy. Its self-assembly behavior as well as photo-responsive behavior in its solution and gel states were investigated. Such a compound can self-assemble into fiber mesophases in water solvent. After irradiation of the gels with UV light, the trans isomer of the compound rapidly photoisomerized to the cis isomer, which resulted in a rapid destruction of the gel. High temperature also caused a rapid drop in viscosity. To verify the antimicrobial activity of the hydrogel, live and death assays of human fibroblasts L929 properties were used for in vitro cell viability studies. The compound was converted to the terminal tertiary amine in a quaternary ammonium salt molecule by using hydrochloric acid. This azobenzene quaternary ammonium salt has a relatively better antimicrobial effect biocidal activity that was demonstrated when challenged against Escherichia coli on in vitro conditions.

Comparative mechanical, morphological, rheological, and thermal properties of polypropylene/ethylene‐propylene‐diene rubber blends

AbstractBecause of its weak durability at low temperatures and low strain rates, polypropylene's use as an engineering plastic is restricted. To make polypropylene more tougher, combine it with elastomeric particles in a cost‐effective manner is an excellent option. Internal melt blending was used to manufacture polypropylene (PP) and high‐molecular‐grade ethylene‐propylene‐diene rubber (EPDM) blends with varying constitutive ratios in this work. EPDM's lower portions have especially high impact strength ratings for PP/EPDM mixtures. (i.e., 2.5, 5, and 7.5 parts per hundred EPDM rubber). The mechanically generated cavitation behavior of impact cracked specimens is obvious from SEM morphology, showing to the strong impact resistance of PP/EPDM blends. Increased EPDM content reduces the amount of scattered EPDM rubber particles by increasing the average diameter of dispersed particles, as seen by HRTEM images of the samples. The tensile and flexural properties of PP/EPDM blends were analysed. The rheological tests demonstrate that as the frequency increases, the complex viscosity drops, indicating that the melt is in a pseudoplastic condition. Due to the destruction of polymer chain mobility at greater cooling rates, DSC analysis indicates that percentage crystallinity values decrease as the cooling rate of crystallization increases, resulting in an incomplete crystallization process. The fact that PP/EPDM mixes have two glass transition temperatures indicates that they are immiscible. An investigation using the TGA found that the maximum degradation temperature (Tmax) of the PP/EPDM rubber mixtures may be sustained for long periods of time at very high operating temperatures.

Synthesis, Characterization and Invivo Evaluation of Poly Sulfoxy Amine Grafted Xanthan Gum

Natural polymers are hydrophilic in nature, economic, chemically inert, easily available, biodegradable, and non-toxic. Following problems associated with the use of gums include uncontrolled rates of hydration, pH dependent solubility, thickening, drop in viscosity on storage, and the possibility of microbial contamination. Chemical modification of gums not only minimizes these drawbacks but also alter their physicochemical properties. Recently, researchers have been modifying properties of natural gums to explore its more applicability. Aim of the current study was to explore Xanthan gum’s applicability in mucoadhesive and other property by doing its Chemical modification. Sulfoxy amine modification of xanthan gum was carried out by reacting xanthan gum with thionyl chloride and further treated with ammonia. FTIR, elemental DSC, XRD and SEM were studied for confirmation of the modification. The modified xanthan gum showed improvement in the mucoadhesion, water uptake capacity, gelling property as well as viscosity as compared to unmodified xanthan gum. The results of X-ray diffraction study confirms the finding of DSC study. X-ray diffractogram confirmed XG is typical of amorphous substance while that of MXG is typical of crystalline substance with the characteristic peak appearing at 14.79, 25.66, 29.63 and 31.82 2θ. The 0.6% w/v of modified xanthan gum showed gelling property. The 0.6% w/v of modified Xanthan Gum showed gelling property where as Xanthan Gum required more than 1% w/v , it indicate that gelling property of Xanthan Gum has improved due to its modification. Mucoadhesive strength of modified xanthan gum was found to be 4±0.56 gm which is more than xanthan gum i.e. 1.5±0.94 gm. The ionic interactions may be taken place in between negatively charged mucus with cationic modified polymer and superior mucoadhesion can be achieved. Rapid and constant swelling behavior was observed by modified Xanthan gum. The SEM image of MXG showed that the grafting of Polysulfoxyamine onto XG brings about the change in the shape and size of the XG particles. The enhanced viscosity and gelling capacity of modified xanthan gum were also observed as compared to xanthan gum. In vivo acute toxicity study of Poly sulfoxy amine grafted xanthan gum was performed. The toxicological effects were observed in terms of mortality and expressed as LD50. Results of Acute toxicity study shows LD50 value was more than 2 gm/kg indicating the low toxicity. These findings proved that modified xanthan gum may be used as promising excipient in various drug delivery systems.

The stability investigation of variable viscosity control in the human-robot interaction.

BackgroundFor many co‐manipulative applications, variable damping is a valuable feature provided by robots. One approach is implementing a high viscosity at low velocities and a low viscosity at high velocities. This, however, is proven to have the possibility to alter human natural motion performance.MethodsWe show that the distortion is caused by the viscosity drop resulting in robot's resistance to motion. To address this, a method for stably achieving the desired behaviour is presented. It involves leveraging a first‐order linear filter to slow the viscosity variation down.ResultsThe proposition is supported by a theoretical analysis using a robotic model. Meanwhile, the user performance in human‐robot experiments gets significantly improved, showing the practical efficiency in real applications.ConclusionsThis paper discusses the variable viscosity control in the context of co‐manipulation. An instability problem and its solution were theoretically shown and experimentally evidenced through human‐robot experiments.

Four-layer model of hydrate slurry flow in pipes considering rheological properties

With the exploitation of deep-water hydrate, the limitations and worrying safety of traditional mining methods such as depressurization gradually pronounced. Therefore, multiphase transportation of slurry draw attention rapidly. Hence, it is necessary to clarify the gas–liquid–solid flow regularity in slurry pipelines and provide accurate guidance for engineering projects. Wherefore, a steady-state four-layer model was developed from Hernandez (2006). The novelties of this model are that the rheological properties of the hydrate slurries were introduced and the effects of concentration distribution (C(y)) both on the solid diffusivity (ε) and interference settling velocity (wm) were considered during the calculation of C(y) in the heterogeneous layer. After improvement, this model can effectively predict the flow state of gas and slurry in pipelines. A comparison with the previous model showed that the prediction accuracy of the proposed model is within 25% for the apparent viscosity and pressure drop gradient in the pipe, indicating that the rheological properties of the hydrate slurries have a non-negligible effect on the flow state. Moreover, the present model improves the prediction accuracy of the hydrate particle C(y) in the heterogeneous layer by considering the interaction between the ε, wm, and C(y). The prediction results of the proposed model for the C(y) and change rate near the interface between the heterogeneous layer and the moving bed layer were in good agreement with the experimental data. Finally, the change laws of the hydrate particle concentration distribution, bed height, and pressure drop gradient under different working conditions were analyzed. Compared with the previous model, there is no flow transition in the velocity range of 0.05–0.5 m/s, and an economic mean concentration exists among the different mean concentrations (CS), which can provide guidance for engineering projects.

Rheology of partially solidified hypoeutectic aluminum copper alloys

This study presents oscillatory and rotational viscosity measurement results on Al-Cu alloys with the goal of achieving effective viscosity data of partially solidified alloys from fully liquid to nearly fully solid state. Rotational viscosity measurements indicate fragmentation of dendrites and a concomitant sudden drop in viscosity of the solid–liquid two-phase mixture upon cooling and increase in solid fraction. This measurement artifact is avoided with oscillatory measurements. The viscosity of partially solid Al-Cu over the hypoeutectic range is nearly composition independent when evaluated as a function of solid fraction. The oscillatory measurements yield a complex viscosity with the real part reflecting the elastic behavior and the imaginary part indicating the viscous part of the viscosity behavior. The measurements of the phase angle in this study reveal that the rheological behavior of the solid phase in the liquid–solid two-phase region resembles that of a liquid more than that of a solid phase.HighlightsOscillatory rheology is shown to be better suited to characterize partially solidified metal alloys than rotational rheology.The viscosity of the liquid phase does not change measurably during solidification despite an increase in the solute content.The solid phase in the liquid–solid two-phase region behaves rheologically more like a liquid than a solid.

A facile strategy to achieve polyurethane vitrimers from chemical recycling of poly(carbonate)

Polyurethane vitrimers (PUVs) incorporating urethane reversion covalent adaptable networks are usually limited by the use of aliphatic alcohol for carbamate groups, resulting in high activation energy for bond exchange. In this study, PUVs bearing phenolic carbamate were demonstrated to overcome the low reactivity between phenol and isocyanate in the consumption of polymer wastes. First, poly(carbonate) (PC) was converted to a versatile intermediate mixture of hydroxyl N, N’-diphenylene-isopylidenyl biscarbamates (DP-biscarbamates). Unlike previously developed products with linear structures, the incorporation of a crosslinking agent, trimethylol propane with multiple functional groups would generate crosslinked structures in PUVs with improved mechanical properties. Due to the active sites provided by phenolic carbamate-containing DP-biscarbamate, the PUV products exhibit a gradual viscosity drop that follows the Arrhenius equation and corresponds to the feature of vitrimers with dissociative covalent adaptable networks. These products exhibit activation energies below 100 kJ/mol for topology rearrangement, facilitating the reprocessability for compression molding at mild temperatures of 120 °C. Overall, this study provides a new insight into an efficient material recycling process by the utilization of polymer waste.

Beeswax Material as Corrosion Inhibitor in a Brake Oil System

One of the most important additives used in the braking system is anti-corrosion providing corrosion protection for metals used in braking systems, including cast iron, aluminum, steel, copper, and brass. Beeswax is a biocorrosion inhibitor in braking systems tested. It is cheap, environmental-friendly, a source of nature, and a secondary product in the life of bees. The additive was added in several concentrations of weight percent (wt%), and the method of weight loss was used to study the effect of beeswax as a corrosion inhibitor. The result is an enhancement in corrosion resistance with beeswax content increasing. Many tests, such as an atomic force microscope (AFM), were used to observe the aluminum surface's topography. The result shows a decrease in surface roughness with beeswax additives. Besides, a rheometer and tensiometer were used to study the flow behavior of brake oil/beeswax at different shear rates and shear stresses. It shows a dramatic drop in viscosity as its concentration increases. Beeswax can be considered an environmentally friendly additive and has exhibited a good corrosion inhibitor even in severe acidic environments. The result showed that the brake oil/beeswax fluid offers excellent corrosion protection for metal components and lubricating properties that reduce wear.

Total and Partial Shear Viscosity in Heavy-Ion Collisions at Energies of BES, FAIR and NICA

We calculated the shear viscosity of hot and dense nuclear matter produced in a symmetric system of central gold–gold collisions at energies of BES RHIC, FAIR and NICA. For calculations of the collisions, the transport model UrQMD was employed. The shear viscosity was obtained within the Green–Kubo formalism. The hadron resonance gas model was used to determine temperature and chemical potentials of baryon charge and strangeness out of microscopic model calculations. In contrast to our previous works, we determined the partial viscosity of the main hadron species, such as nucleons, pions, kaons and Lambdas, via the nucleon–nucleon, pion–pion and so forth, correlators. A decrease in the beam energy from Elab=40 to 10 AGeV leads a to rise in baryon shear viscosity accompanied by a drop in the shear viscosity of mesons. The ratio of total shear viscosity to entropy density also decreases.

The influence of microbial transglutaminase on camel milk yogurt

This study investigates camel milk yogurts made with microbial transglutaminase (mTGase) at two different concentrations (3 and 6 U/g protein) and three different protein sources (micellar casein, whey protein concentrate, and sodium caseinate) and assesses their physical, chemical, and sensory properties. Of thirty samples, five were selected for further testing based on their viscosity and rapid pH drop during fermentation. During fermentation, many volatile compounds were formed, namely acetaldehyde, diacetyl, acetyl propionyl, ethanol, hexanal, and methane. Acetaldehyde percentages were lower with higher mTGase concentrations. All three milk protein powders increased the diversity of volatile compounds. Electrophoresis results showed that monomer band intensity decreased with higher mTGase concentrations. Lower-intensity monomer bands were formed at higher mTGase concentrations. Among the five optimal samples, the best microstructure was obtained in the sample produced with 6 U/g mTGase and 6.2 g/100 mL whey protein concentrate. The sample with the best sensory properties was prepared with 6 U/g mTGase and micellar casein. In conclusion, mTGase improved the gel structure and sensory properties of camel yogurt.

A comparative study of rheological behavior in hybrid nano-lubricants (HNLs) with the same composition/nanoparticle ratio characteristics and different base oils to select the most suitable lubricant in industrial applications

Today, many experimental-theoretical studies are being conducted to investigate the thermophysical properties of nanofluids and nano-lubricants in the world. In this research, the rheological behavior of hybrid nano-lubricants (HNLs) to the independent variables affecting it is analyzed comparatively. Lab seeing show that under different laboratory conditions, HNLs have a pseudo-plastic non-Newtonian behavior. The relationships between viscosity changes and temperature, SVF and SR are observed in reverse, direct and inverse, respectively. It is found that at low SRs, HNL containing 5W50 experiences a greater viscosity drop compared to HNL containing SAE40. After analyzing the emprical results by RSM, a new three-variable-quadruple correlation relationship with an accuracy of R2 = 0.9994 is presented to predict the viscosity of selected HNLs. The MOD of the proposed model is measured within the allowable range − 3.58%<MOD< 4%. By examining the sensitivity analysis of viscosity in different SVFs, the highest viscosity effect occurs in φ = 1% and T = 55 °C, which is equal to 8.41%.