Yielding characterization of waxy gels by energy dissipation

Liu, Hongfei; Zhang, Jinjun; Lu, Yingda

doi:10.1007/s00397-018-1094-8

Cited by 16 publications

(4 citation statements)

References 47 publications

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“…The SP80AATG at 4 °C exhibited an elastic deformation till the shear stress point 200 s −1 and was followed by gel fracture in a brittle manner indicating an abrupt stress decay ( Figure 1 B). However, at 25 °C and 40 °C, SP80AATG showed a broader and smooth strain evolution in the yielding zone as shown on the graph, which indicated a more ductile fracture with considerable plastic deformation or permanent deformation [ 40 ].…”

Section: Resultsmentioning

confidence: 99%

Preparation, Characterization and Permeation Study of Topical Gel Loaded with Transfersomes Containing Asiatic Acid

et al. 2022

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The objective of this study is to investigate the in vitro permeation of asiatic acid (AA) in the form of a topical gel after entrapment in transfersomes by Franz diffusion cells. Transfersomes composed of soybean lecithin and three different edge activators including Tween 80 (TW80), Span 80 (SP80) and sodium deoxycholate (SDC) at the ratio of 50:50, 90:10 and 90:10, respectively, together with 0.3% w/w of AA, were prepared by a high-pressure homogenization technique and further incorporated in gels (TW80AATG, SP80AATG and SDCAATG). All transfersomal gels were characterized for their AA contents, dynamic viscosity, pH and homogeneity. Results revealed that the AA content, dynamic viscosity and pH of the prepared transfersomal gels ranged from 0.272 ± 0.006 to 0.280 ± 0.005% w/w, 812.21 ± 20.22 to 1222.76 ± 131.99 Pa.s and 5.94 ± 0.03 to 7.53 ± 0.03, respectively. TW80AATG gave the highest percentage of AA penetration and flux into the Strat-M® membrane at 8 h (8.53 ± 1.42% and 0.024 ± 0.008 mg/cm2/h, respectively) compared to SP80AATG (8.00 ± 1.70% and 0.019 ± 0.010 mg/cm2/h, respectively), SDCAATG (4.80 ± 0.50% and 0.014 ± 0.004 mg/cm2/h, respectively), non-transfersomal gels (0.73 ± 0.44 to 3.13 ± 0.46% and 0.002 ± 0.001 to 0.010 ± 0.002 mg/cm2/h, respectively) and hydroethanolic AA solution in gel (1.18 ± 0.76% and 0.004 ± 0.003 mg/cm2/h, respectively). These findings indicate that the TW80AATG might serve as a lead formulation for further development toward scar prevention and many types of skin disorders.

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Section: Resultsmentioning

confidence: 99%

Preparation, Characterization and Permeation Study of Topical Gel Loaded with Transfersomes Containing Asiatic Acid

et al. 2022

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“…Rheometry. The gelation temperature and apparent viscosity of the crude oil samples were measured by a HAAKE Mars III rheometer (Thermo Fisher Scientific, Inc., Germany) equipped with a coaxial cylinder sensor system 27 with rough surfaces (Z38 TiP). The procedures for these two types of rheometric characterization are provided below.…”

Section: Methodsmentioning

confidence: 99%

Effect of Pour Point Depressants on the Impedance Spectroscopy of Waxy Crude Oil

Chen

Huang

et al. 2020

Energy Fuels

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Treatment with pour point depressant (PPD) can significantly improve the cold flowability of waxy crude oil, enabling the safe and efficient transportation of waxy crude oils through pipelines. It has been observed that the electrical properties of waxy oil, such as the dielectric constant, ζ-potential, etc., change upon PPD treatment. In a previous study, we reported that wax precipitation results in a significant change of impedance spectroscopy (IS) of a waxy oil, i.e., a second semicircle appears in the Nyquist diagram and becomes increasingly bigger with increasing amount of precipitated wax. In this study, we found that the addition of PPD may significantly reduce the second semicircle, and the more effective the PPD is, the more reduced the second semicircle will be. Equivalent circuit models suggest that the impedance characteristics of the liquid phase of wax-in-oil suspension change little with PPD addition, but the capacitance of wax particles increases and the resistance of wax particles decreases significantly. A positive correlation between the viscosity reduction and the reduction of resistance of wax particles caused by PPD is discovered. After PPD treatment, the polar functional groups in PPD molecules potentially induce charge on wax particles as they precipitate, causing the relationship between the viscosity and conductivity to approach the fractional Walden rule. This work explains the reason for the improvement of flowability upon PPD addition from a perspective of IS, which provides some new proofs to understanding the functional mechanism of PPD.

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“…Moreover, as discussed above, various materials in the gel-like state may exhibit viscoelastic rather than purely elastic behavior [ 4 , 5 , 138 , 162 , 163 ]. This should also be included in a complete visco-elasto-fluid thixotropic rheological model of real yielding stress liquid [ 164 , 165 , 166 ]. This complicated model has been examined, although there are difficulties in determining the constants of the model [ 128 , 160 , 167 ].…”

Section: On the Yield Stress In Soft Mattermentioning

confidence: 99%

Rheology of Gels and Yielding Liquids

Malkin,

Derkach,

Kulichikhin

2023

Gels

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In this review, today’s state of the art in the rheology of gels and transition through the yield stress of yielding liquids is discussed. Gels are understood as soft viscoelastic multicomponent solids that are in the incomplete phase separation state, which, under the action of external mechanical forces, do not transit into a fluid state but rupture like any solid material. Gels can “melt” (again, like any solids) due to a change in temperature or variation in the environment. In contrast to this type of rheology, yielding liquids (sometimes not rigorously referred to as “gels”, especially in relation to colloids) can exist in a solid-like (gel-like) state and become fluid above some defined stress and time conditions (yield stress). At low stresses, their behavior is quite similar to that of permanent solid gels, including the frequency-independent storage modulus. The gel-to-sol transition considered in colloid chemistry is treated as a case of yielding. However, in many cases, the yield stress cannot be assumed to be a physical parameter since the solid-to-liquid transition happens in time and is associated with thixotropic effects. In this review, special attention is paid to various time effects. It is also stressed that plasticity is not equivalent to flow since (irreversible) plastic deformations are determined by stress but do not continue over time. We also discuss some typical errors, difficulties, and wrong interpretations of experimental data in studies of yielding liquids.

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Yielding characterization of waxy gels by energy dissipation

Cited by 16 publications

References 47 publications

Preparation, Characterization and Permeation Study of Topical Gel Loaded with Transfersomes Containing Asiatic Acid

Preparation, Characterization and Permeation Study of Topical Gel Loaded with Transfersomes Containing Asiatic Acid

Effect of Pour Point Depressants on the Impedance Spectroscopy of Waxy Crude Oil

Rheology of Gels and Yielding Liquids

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