Dynamic Viscoelastic Measurements Research Articles

Rheological properties of halloysite soil slurry: a case study of weathered tephra involved in a shallow landslide triggered by the 2018 Eastern Iburi earthquake in Hokkaido, Japan

The 6.7 Mw Eastern Iburi earthquake of 6 September 2018 triggered destructive landslides in southern Hokkaido, Japan, many of which were characterized by the flow-like downslope movement of volcanic soils formed from weathered tephra containing halloysite. This study aims to elucidate the mechanism of landslide generation through rheological characterization of halloysite soil slurries. The examined slurries were prepared from either oven-dried or moist soil. Both slurries showed a power-law correlation between measured yield stress and moisture content. However, at a given water content, slurry made from dried soil showed stresses that are one-to-two orders of magnitude lower than those of slurry made from moist soil. Compared with the measurements for the slurry of dried soil, those for the slurry of moist soil are closer to prior numerical modeling of a specific landslide, indicating that the soils involved were moist. The yield stress also varied with slurry pH, generally increasing with decreasing pH, which is in part explained by the DLVO force model based on the electrical double layer and van der Waals forces between the colloidal particles. The pH dependence is more prominent in the slurry of moist soil, and thus the mechanical state of the slope appears to vary significantly with rainfall-induced changes in subsurface chemistry. Dynamic viscoelasticity measurement indicated that both initially solid-like slurries can become fluid under an applied oscillatory strain of 0.5 to 10 Hz: the susceptibility to fluidization depends greatly on water content and frequency. The ground motion during the earthquake easily fluidized the slurry, indicating this was a factor contributing to the observed flow-like landslides.Graphical

Rheological properties of Sesbania cannabina galactomannan as a new source of thickening agent.

The present study evaluated the rheological properties of galactomannan from Sesbania cannabina. The intrinsic viscosity of galactomannan was determined to be 8.63± 0.06 dl/g. Moreover, the onset of galactomannan coil overlap occurred at 5.12± 0.13g/L. With increasing concentration, galactomannan showed a more distinct shear-thinning behavior, which was well characterized by the Cross model. Notably, the viscosity of polysaccharide showed a negative relationship with the temperature, while the activation energy decreased with increasing polysaccharide concentration. Furthermore, at high concentrations, the galactomannan solution showed stability after heating or freezing, as well as over the wide pH range of 5.0-9.0. Dynamic viscoelasticity measurements reveal a gradual transition from viscous to elastic behavior of galactomannans with an increasing frequency. It is anticipated that S. cannabina galactomannan will find interesting applications as a natural thickener due to the comprehensive description of its rheological properties presented herein. PRACTICAL APPLICATION: The investigated S. cannabina galactomannan has shown a higher viscosity and heat stability at high concentration, as well as a good stability at the pH range of 5-9. The S. cannabina galactomannan may be employed as stabilizers in the food field.

Molecular Mechanisms Involved in Thermally Induced Gel Formation of Japanese Codling Meat Paste during a Two-Step Heating Procedure

We analyzed changes in the rheological properties of Japanese codling (Physiculus japonicus) meat paste during the following two-step heating procedure: first preheating at 0–70 °C with 5 or 10 °C intervals and subsequent secondary main heating at 85 °C. Changes in the breaking strength and breaking strain rate showed roughly three phases associated with preheating temperatures of 0–25, 30–50, and 55–70 °C. The most prominent change was observed for preheated gels with preheating from 30 to 55 °C, where the myosin polymerization rate was high. The increase in the preheating temperature from 0 to 25 °C was accompanied by a gradual decrease in protein solubilization and a rapid increase in myosin polymerization for preheated gels, suggesting that gel formation occurred even at low preheating temperatures. Dynamic viscoelasticity measurements indicated that structural changes in myosin other than polymerization also participate in gel formation. Moreover, NH4Cl, an inhibitor of transglutaminase, reduced myosin polymerization in meat paste.

Voids induce wide-range modulation of elasticity for magnetic elastomers.

The relationship between the magnetorheological effect and the void ratio for a polyurethane magnetic elastomer with voids was investigated using a dynamic viscoelastic measurement under a magnetic field of 500 mT. The magnetic elastomer contains iron particles with a diameter of 235 μm at a concentration of 85 wt% (volume fraction: 0.43). The void ratio defined using the volume of vacancies in the non-filled volume of magnetic particles was increased by reducing the amount of polyurethane up to a maximum void ratio of 0.56. The storage modulus of the magnetic elastomer without voids was 1.5 × 105 Pa at 0 mT and 3.1 × 105 Pa at 500 mT, respectively; that is, no significant change in the modulus was observed. The storage modulus at 0 mT for the magnetic elastomer was independent of the void ratio, while the storage modulus at 500 mT increased in proportion to the void ratio. At a void ratio of 0.56, the storage modulus for the magnetic elastomer was 5.6 × 105 Pa at 0 mT and 6.1 × 106 Pa at 500 mT, respectively; that is, the magnetic elastomer demonstrated a significant change in the storage modulus on the order of MPa. This strongly indicates that production of voids enables movement of magnetic particles in the elastomer. Under both strains of 10-4 and 1, a significant and reversible response of storage modulus was observed after the first application of magnetic field even though the magnetic field was applied for 20 cycles, meaning that the change in the modulus is perfectly reversible although the elastomer contains many voids. SEM/EDX observations revealed that the area composed of carbon decreased with the increasing void ratio while the area composed of iron remained unchanged.

Measurement and Modeling of Dynamic Viscoelasticity

Measurement and Modeling of Dynamic Viscoelasticity

Characterization of the effect of dry-heat treatment on the gelation of alkaline dried egg whites using dynamic viscoelastic measurement and ultrasound spectroscopy

In the present study, the mechanism for gelation of dried egg whites (DEWs) samples, which were differentially pretreated with dry-heat treatment and alkaline pH, were investigated using dynamic viscoelastic measurements and ultrasound spectroscopy for gels formed with at high protein concentrations. Rheological measurements showed that DEW gels with dry-heat treatments have a higher dynamic complex modulus than DEW gels without dry-heat treatments. Furthermore, ultrasonic attenuation analyses showed that subjecting DEWs to dry-heat treatment and alkaline pH induced the formation of an increased number of DEW protein “soluble aggregates” compared with unheated and neutral DEWs. Our data suggests that pretreatment of DEW samples led to partially unfolded DEW proteins with more “soluble aggregates”, which were strongly correlated with the formation of gels with a more homogeneous and rigid texture. Understanding their structural properties at a molecular detail would enable desirable textural modifications for the development of new food products.

Effects of the Hofmeister anion series salts on the rheological properties of Sesbania cannabina galactomannan

Sesbania cannabina galactomannan (2%) solutions added with strongly hydrated ions (Na2CO3, NaH2PO4, NaCl) and weakly hydrated ions (NaNO3) at different ionic strengths were rheologically characterized. The four selected salts dramatically decreased the intrinsic viscosity of galactomannan solution in the following order of effectiveness: Na2CO3 < NaH2PO4 < NaCl < NaNO3. This conforms effectively to the Hofmeister anion series. Moreover, salt addition increased the viscosity of galactomannan solution when the ionic strength was 1 mmol/kg, which related to an increased occurrence of intermolecular interactions. As increasing ionic strength, galactomannan chains may tend to contract or expand due to the presence of strongly or weakly hydrated ions, thereby decreasing the viscosity. These phenomena were demonstrated by zeta potential measurement and again observed in dynamic viscoelasticity measurement. Overall, this property can be used to manipulate the rheological properties of galactomannan in food gums to obtain gums of high quality for enhancing consumer goods.

Solid Fat Replacement with Canola Oil-Carnauba Wax Oleogels for Dairy-Free Imitation Cheese Low in Saturated Fat.

Canola oil was structured into oleogels with different amounts of carnauba wax, and their processing performances were assessed as an alternative to solid fat for imitation cheese low in saturated fat. The contents of solid fat in the oleogels were less vulnerable to the change in temperature than the palm oil. The replacement of palm oil with oleogels produced cheese samples with harder and more cohesive/chewy textures. Dynamic and transient viscoelastic measurements demonstrated that the use of oleogels was effective in increasing the elastic nature of the cheeses. Two distinct components with different proton mobilities were observed in the imitation cheeses, and longer T2 relaxation times were detected in the oleogel samples. The meltability of the cheese with palm oil was not significantly different from those with 3% and 6% oleogels. The saturated fat level of the oleogel cheese was significantly reduced from 45.70 to 5.20%. The application of canola oil-carnauba wax oleogels could successfully produce imitation cheese high in unsaturated fat and low in saturated fat. This study thus demonstrated that the health-functional properties of imitation cheese could be enhanced by using oleogels.

Effect of Alkyl Chain Length of N-Alkyl-N'-(2-benzylphenyl)ureas on Gelation.

Urea derivatives that were substituted with a 2-benzylphenyl group and an alkyl group functioned as low molecular weight gelators for various organic solvents and ionic liquids. Urea derivatives with long alkyl chains were effective for the gelation of polar solvents. However, they were not suitable for the gelation of non-polar solvents, whereas urea derivatives with short alkyl chains were effective. Ionic liquids were similar to polar solvents in that urea derivatives with long alkyl chains were the most effective gelators. The physical properties of the formed supramolecular gels were analyzed by dynamic viscoelasticity measurements using a rheometer.

Gelation of Konjac glucomannan crosslinked by organotitanium chelated with different ligands

Konjac Glucomannan (KGM) gels can be formed in the presence of organotitanium as crosslinkers which were chelated by different organic compounds. Organotitanium cross-linking agent is a chelate formed by coordination between tetrabutyl titanate and different organic compounds. The gel network was formed through the crosslinking reaction between titanium ions dissociated from organotitanium crosslinkers and the cis-diol hydroxyl groups on the mannose units of polysaccharide chains. Effect of concentration and species of ligands on rheological properties of the complex gels was studied by dynamic viscoelastic measurements. The gelation kinetics of the gels were investigated and the critical gelation points of the gels were accurately determined according to the Winter-Chambon criterion. The effects of kinds and concentrations of ligands on the shear storage modulus (G’), the loss modulus (G”), and the sol-gel transition points were studied. The sol-gel transition time varies with different ligands in the organotitanium crosslinkers. The sol-gel transition time and temperature were obviously observed and in good agreement with Winter–Chambon criterion.

Viscoelastic behavior of alkali and alkaline earth aluminophosphate glasses

• Viscoelasticity of alkali and alkaline-earth aluminphosphate glass was investigated. • Activation energy of stress relaxation changed with aluminum content. • Different change in two series would be due to existence of AlO 4 . The viscoelastic behavior of alkali and alkaline earth aluminophosphate glasses was studied. The energetic interpretation was based on the Arrhenius behavior of the relaxation modulus. With increasing aluminum content, the activation energy of the relaxation increased in the alkali series but decreased in the alkaline earth series. Dynamic viscoelasticity measurements revealed that the loss modulus, E ”(ω), showed a crossover of the relaxation process at the glass transition temperatures. The activation energy below the transition temperature was close to the energies of internal friction or ionic self-diffusion. The energy above the transition temperature corresponded to the dissociation energies of alkali-oxygen or alkaline earth-oxygen single bonds. The different behavior in the energy of the relaxation modulus between alkali and alkaline earth series was due to weak bonds caused by adding alkali ions and the formation of crosslinking by low-coordinate aluminum polyhedra because of the presence of alkaline earth ions.

Assessment of turanose as a sugar alternative in a frozen dough system: Rheology, tomography, and baking performance

Turanose was evaluated as an alternative to sugar in a frozen dough system in terms of rheology, tomography, and baking performance. The use of turanose for sugar did not negatively affect the thermo-mechanical parameters of wheat dough including development time and stability. In the case of thermal properties, the gelatinization temperature was lowered by turanose from 68 to 64°C. The dynamic viscoelastic measurements demonstrated that the turanose-incorporated doughs showed more viscous characteristics by showing greater decreases in the storage modulus that could also be related to greater dough extensibility. When the frozen doughs were baked, the turanose-incorporated bread showed a significant increase in its specific loaf volume from 4.23 to 4.41 mL/g. These volume differences could be attributed to the inner structural characteristics (increased total volume of pore space and total porosity) of the breads measured by the tomographic analysis. Furthermore, the positive effects of turanose on the soft texture of frozen dough breads were distinctly observed.

Development of a Near-infrared Laser-induced Surface Deformation (NIR-LISD) microscope and its application to the dynamic viscoelastic measurements of living plant surfaces at single-cell level

Development of a Near-infrared Laser-induced Surface Deformation (NIR-LISD) microscope and its application to the dynamic viscoelastic measurements of living plant surfaces at single-cell level

Method of Viscoelasticity Measurement under Shear-Flow

In anticipation of that direct examination of the shear flow affection on the dynamic viscoelasticity might bring more comprehensive results than the LAOS method, a series of dynamic viscoelasticity measurements with parallel superposition of steady shear flow was planned. The measured values which are function of shear rate ̇γ, that is, storage and loss moduli G′(̇γ), G″(̇γ) and viscosity η(̇γ), are analyzed as three non-dimensional parameters G′(̇γ) / G′(0), G″(̇γ) / G″(0) and η(̇γ) / | η*(ω, ̇γ) |, where η* is complex viscosity. A Couette rheometer ONRH-1b (OhnaTech) was employed, and for the samples, hydroxypropyl cellulose, xanthan gum, carboxyvinyl polymer and C24-hydrophobically modified ethoxylated urethane ware used. All three analyzing parameters show clearly the differences of samples. It is found that the nature of their responses are subjected not by the shear itself, but by the value that divided shear rate with measure frequency (̇γ/ω). On the other hand, it is found that the properties that are subjected by the shear rate do exist. Observation of these results asserts that multifactorial rheological measurement including this superposition method is worthwhile.

Characterization of the gelation and resulting network of a mixed-protein gel derived from sodium caseinate and ovalbumin in the presence of glucono-δ-lactone

We investigated mixed-protein gels made from sodium caseinate and ovalbumin at different ratios with use of the acidification agent glucono-δ-lactone. Dynamic viscoelastic measurements revealed that increasing the ovalbumin content decreased the mechanical properties of the gel but accelerated onset time of the phase transition. Ultrasound spectroscopy during gelation revealed that the relative velocity gradually decreased, whereas the ultrasonic attenuation increased during the whole acidification process until gelation was complete, although these changes were much smaller than those observed with heat-induced gelation. Confocal laser scanning microscopy along with scanning electron microscopy revealed that although uniform mixing of sodium caseinate and ovalbumin was observed, sodium caseinate is likely to mainly lead formation of the gel network, and the porosity of the resulting gel network depends on the ratio of these two components. The results demonstrate that confocal laser scanning microscopy is a useful tool for analyzing both the networks within mixed-protein gels and the contribution of each protein to the network and gelation.

Physicochemical Properties of Mucin Extracted from &lt;i&gt;Misgurnus mizolepis&lt;/i&gt; Epidermal Mucus

The purpose of this study was to investigate the extraction yield and physicochemical characteristics of mucin from the epidermal mucus of Misgurnus mizolepis. Ninety percent ethanol produced the highest yield of mucin. At higher concentrations, mucin had more elastic properties, as revealed by dynamic viscoelasticity measurements. Differential scanning calorimetry (DSC) demonstrated that mucin is a thermostable glycoprotein. Denaturation enthalpy increased as mucin concentration increased. Mucin inhibited the growth of both Escherichia coli and Bacillus cereus, but had better antimicrobial activity in the former. Mucin also exhibited antioxidant activity, equivalent to 66.64% of that of L-cysteine. Mucin inhibited elastase activity and MMP-1 & MMP-2 expression activity, and induced hyaluronic acid expression. It is indicating that mucin is effective in moisturizing and anti-aging the skin. Thus, mucin from the epidermal mucus of Misgurnus mizolepis could have great potential as a non-food material in various industries.

Mixing and Elastic Contributions to the Diffusion Coefficient of Polymer Networks

Because the swelling of polymer gels is a diffusion process of the polymer network, the swelling rate is determined by the diffusion coefficient of a polymer network. The diffusion coefficient (D) includes the polymer–solvent mixing contribution (Dmix) and the elastic contribution from the polymer network (Del). In this study, we experimentally investigate D, Dmix, and Del, using tetra gels whose network structural parameters are systematically controllable. We measured D and the shear modulus (G) using dynamic light scattering and dynamic viscoelastic measurement, respectively. According to the Tanaka–Fillmore theory, we evaluate Dmix and Del using the linear relationship between D and G in the as-prepared state. Consequently, we demonstrate a relation of D = Dmix + Del in the as-prepared, swelling, and equilibrium swollen states.

Thermo-rheological effects on successful 3D printing of biodegradable polyesters

Biodegradable polybutylene succinate (PBS) and poly (butylene succinate-ran-adipate) (PBSA) were characterized to find the thermo-rheological bases for 3D printing by Fused Filament Fabrication (FFF). In dynamic viscoelastic measurements, the samples fulfilled time-temperature superposition and Cox Merz rule. The viscosity results were linked to the excellent filaments obtained and the observed good flow in the printer nozzle. Using specific tearing experiments, outstanding welding of the printed layers was obtained. Results were discussed considering the values of the entanglements density obtained by small amplitude oscillatory shear (SAOS) measurements. The main difference between both polymers was observed in the final production of 3D printed parts because the high crystallinity of PBS produced significant warpage, which prevented its use for practical purposes. On the contrary, the less crystalline PBSA random copolymer showed excellent performance during FFF. Thus, dimensionally stable and ductile printed objects were obtained, opening new processing routes for semi-crystalline biodegradable polyesters.

Electrical Conductivity of Multiwalled Carbon Nanotube/Acrylonitrile Butadiene Styrene Polymer Nanocomposites prepared by Melt Mixing: Comparison of Twin Screw Extrusion and Batch Mixing

Most polymeric materials are insulators. They can be rendered conductive by the addition of appropriate fillers [1]. To obtain the desired conductivity and to ensure spatial homogeneity of the composite, excellent dispersion of the fillers is considered necessary [1,2]. To prepare the composite, solution casting has been widely used and past work suggests that it can adequately disperse the filler in a polymer matrix [3,4]. However, the method involves long preparation times and large quantities of organic solvents, and is not easily scalable. Melt mixing [4-6] offers an attractive alternative as past work [4,5] suggests that it can yield polymer nanocomposites with conductivities similar to that of solution cast samples. They however utilized laboratory scale batch mixing but industrial scale compounding is often performed using melt extrusion [6]. Therefore, in this work, we have investigated the feasibility of twin-screw melt extrusion for nanocomposite preparation by comparing the electrical conductivity of multiwalled carbon nanotubes (MWCNT) filled acrylonitile-butadiene-styrene (ABS) nanocomposites thus prepared to those obtained using internal batch mixing.First, we measured the electrical conductivity of the polymer nanocomposites prepared by the two methods. As can be seen from Fig. 1, for the samples prepared using the batch mixer, the conductivity exhibited a rapid increase of several orders of magnitude upon addition of a small quantity of MWCNT (less than 1 vol%). Upon further addition of MWCNT, the conductivity increase became less steep. The observed behavior is consistent with results in the literature [1,4] and can be interpreted using percolation theory, which suggests that the sharp increase in the conductivity observed at a certain volume fraction arises because the filler forms a conducting path that percolates across the polymer matrix [1]. Unexpectedly however, for the samples prepared using the twin screw extruder, the results were markedly different in that very little increase in conductivity was observed. If the above interpretation using percolation theory [1] is well founded, this suggests the absence of a percolation path consisting of the MWCNT.Due to van der Waals attraction, MWCNT tend to aggregate into micron scale clusters. During nanocomposite preparation these clusters must be broken down to facilitate the dispersion of the MWCNT in the matrix. As sufficient dispersion is believed to be necessary for the formation of the conducting path [1,2], we performed dynamic viscoelasticity measurements of the samples prepared by both methods to assess the dispersion state of MWCNT. At 0.227 vol% MWCNT, the storage modulus, G’, at low frequencies is lower for the samples prepared using the batch mixer when compared to that prepared using the extruder. Following [1,4], this can be taken to suggest that the dispersion of the MWCNT is poorer in the extruded samples and can be hypothesized to be the reason for the low conductivity. Upon increasing the MWCNT content, the low frequency G’ of the samples prepared by both methods differed little from each other and exhibited a plateau. A low frequency plateau in G’ is typically considered indicative of the presence of a network structure [1,4]. Data in Fig. 2 would suggest that, at the higher volume fractions, both preparation methods results in the formation of a MWCNT network structure. However, the conductivity values for the two methods are vastly different. If high electrical conductivity cannot arise in the absence of a percolating path, that would suggest the absence of a network structure and directly contradicts the implications of the rheology data. Future work will focus on resolving this contradiction using other methods to characterize the dispersion of the MWCNT in the ABS matrix.[1] R. M. Mutiso and K. I. Winey, in Polymer Science: A Comprehensive Reference, edited by K. Matyjaszewski and M. Möller, (Elsevier, Amsterdam, 2012), pp. 327.[2] M. H Kim et al., Korea – Australia Rheology Journal, 31, 179 (2019).[3] M. H. Al-Saleh, H. K. Al-Anid, and Y. A. Hussain, Composites Part A: Applied Science and Manufacturing, 46, 53 (2013).[4] S. K. Sukumaran et al., Journal of The Electrochemical Society, 166, B3091 (2019).[5] S. Dul, A. Pegoretti, and L. Fambri, Nanomaterials, 8, 674 (2018).[6] A. Dorigato, V. Moretti, S. Dul, S. H. Unterberger, and A. Pegoretti, Synthetic Metals, 226, 7 (2017).Fig.1 Variation of σ with ϕ: comparison of nanocomposites prepared using a twin-screw extruder (■) and using an internal batch mixer (●).Fig. 2 Variation of G’ with ω at 200℃ for several ϕ: melt extrusion (solid symbols) and batch mixing (hollow symbols). The data for neat ABS is also shown. Figure 1

Synergistic Effect of Cocamidopropyl Betaine and Sodium Lauroyl Sarcosinate

In this study, we investigated the synergistic effect of a zwitterionic surfactant (cocamidopropyl betaine) and amino acid surfactant (sodium lauroyl sarcosinate) by measurements of surface tension, rheological properties, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The results confirm the formation of wormlike micelles in the mixed system, which leads to superior surface activity as compared to that of an individual surfactant. Stable and dynamic viscoelastic measurements were also performed to explore the characteristics of wormlike micelles at different mole fractions, pH values, and temperatures. The results indicate that the strongest wormlike structure formed under the conditions of X1 = 0.5, pH = 4.7, and CT = 600 mmol/L. The size and morphology of the mixed micelles were obtained by DLS and TEM. The results of this work offer insight into the interaction between zwitterionic and amino acid surfactants, which will contribute to the design of complex surfactants.