Signatures of physical aging and thixotropy in aqueous dispersion of Carbopol

Agarwal, Mayank Mohan; Joshi, Yogesh M.

doi:10.1063/1.5097779

Cited by 36 publications

(48 citation statements)

References 82 publications

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“…The constituting elements within the system had mobility, and this in turn led to them exploring the phase space, altering its' configuration over time to lower their free energy. The need to minimize free energy (physical ageing) was what [24] believed to be the cause for the drop in viscosity observed; the present study does not agree with this hypothesis as it needs further validation.…”

Section: Introductioncontrasting

confidence: 73%

“…There have been studies to understand the ageing phenomena in Carbopol systems, where it has been shown that the viscosity, storage (G′) and loss (G″) moduli changed over time for water-based gel systems [24,25]. One hypothesis advanced by Agarwal et al [24], was that the changes in viscosity were due to physical ageing. It was suggested that the gel systems were in a high free energy state upon initial formulation.…”

Section: Introductionmentioning

confidence: 99%

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Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type

Kolman

Smith

Chakrabarty³

et al. 2021

Intern J of Cosmetic Sci

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Objective:The main objective of this paper is to analyse and attempt to understand the nature of rheological changes observed and the dynamics of Carbopol NF 980 hydroalcoholic gels neutralized specifically by triethanol amine (TEA), both as a function of time and alcohol type to probe time stabilities and ageing effects in such carbopol gel systems. The rheological changes and dynamics of 3 carbopol gel systems were observed; the gels included a water-based, ethanolbased, and isopropyl alcohol-based gel. It is hoped that this study shall shed light on the dynamical nature and the microstructural evolution of such networked gel systems, which were maintained under closed isothermal conditions and left completely unperturbed. The experimental results can provide the information necessary to understand and proposes plausible mechanisms guiding this dynamical behaviour in hydroalcoholic carbopol gels.Methods: A TA instrument mechanical rheometer was used to measure the viscosity and storage and loss modulus, and a pH meter was utilized to determine the changes in each sample over the period.Results: Studying the differences in the gel structures upon initial preparation illustrated that the ethanol and isopropyl alcohol (IPA) gels differed from the water-based gel in terms of viscosity, G′, and G″, with the IPA gel displaying the lowest viscosity and moduli values across all shear rates. All the three gel systems exhibited strong shear thinning characteristics and were reminiscent of yield stress type found in colloidal gels. The water-based gel compared to the hydroalcoholic gels was strongly G′ dominated, with the magnitude of the difference between G′ and G″ observed to be much higher. This reflects that initial formation of the water-based gel structure possesses a much more rigid structure with a high elastic modulus component dominating. This also suggests that the water-based gel structure displayed stronger interactions between the carbopol particles when compared to those of the hydroalcoholic gels. Over the 30-day period, it was observed that the ethanol and water-based gels did not reveal any appreciable viscosity changes, with only an approximate 12% and 7% change from day 1 to 30, respectively. It was observed that the IPA systems' viscosity drastically increased over the period, with an approximately 77% change from day 1

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Section: Introductioncontrasting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type

Kolman

Smith

Chakrabarty³

et al. 2021

Intern J of Cosmetic Sci

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“…5). The ability to measure the effect of time can also be useful to investigate the complex coupling between viscoplastic deformation, aging, and rejuvenation (Agarwal and Joshi 2019;Coussot 2018;Joshi and Petekidis 2018). Moreover, the methodology used appears competitive compared to some others (Kashani et al 2015) for its simplicity.…”

Section: Conclusive Remarksmentioning

confidence: 99%

An alternative approach for measuring yield stress and its application in Carbopol microgel

et al. 2021

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An innovative experimental apparatus for the direct measurement of yield stress was conceived and realized. It is based on a torsion pendulum equipped with a magnetic dipole and a rotating cylinder immersed in the material to be investigated. The pendulum equilibrium state depends on the mechanical torque applied due to an external magnetic induction field, elastic reaction of the suspension wire, and shear yield stress. Experimental results are reported showing that the behavior of the pendulum rotation angle, in different equilibrium conditions, provides evidence of the yield stress presence and enables its evaluation by equilibrium equations. The dependence on time of the equilibrium approach was also studied, contributing to shed light on the relaxation effect in the transition from a fluid-like to solid-like behavior, as well as on the eventual thixotropic effects in non-Newtonian fluids. The validity of the proposed technique and related experimental apparatus was tested in aqueous Carbopol solutions, with different weight percentages. The linear procedure, combined with the effectiveness and reliability of the proposed experimental method, candidates it to be used for the study of peculiar behaviors of other yield stress complex fluid such as blood, crude waxy oils, ice slurries, and coating layer used in the food industry and also for fault sliding in geodynamics.

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“…Within dynamic experiments, the sample is exposed to a forced sinusoidal oscillation and the transmitted stress is measured. Both types of testing are used for the evaluation of structure and physical aging of aqueous dispersions of carbomer gels (17,(39)(40)(41). The results of the oscillatory rheological characterization of the investigated hydrogels are presented in Table V and Figure 3.…”

Section: Table III Apparent Viscositiesmentioning

confidence: 99%

“…The application properties of hydrogels largely depend on formulation factors that may affect the rheological characteristics of the system, including physico-chemical properties and concentrations of a gelling agent and an active substance. The most often used gelling agents in topical hydrogels are carbomers, which represent high-molecular homo-polymers of acrylic acid crosslinked by polyethers (16,17). Carbomer hydrogels are viscoelastic systems obtained by the dispersion of polymer powders in water and subsequent neutralization with a suitable base, so that the dry particles swell, and polymer chains undergo extensive expansion (15).…”

Section: Introductionmentioning

confidence: 99%

Rheological behavior study and its significance in the assessment of application properties and physical stability of phytosome loaded hydrogels

Djekić¹,

Krajišnik²

2021

Arhiv za farmaciju

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Phytosomes are amphiphilic molecular complexes of substances of plant origin and phospholipids that are considered as active ingredients of dermopharmaceutical and cosmetic formulations of potentially improved efficiency. The study aim was the formulation of carbomer hydrogels with commercially available phytosomes of escin (Escin ß-Sitosterol Phytosome®) (EP) and 18-ß glycyrrhetinic acid (18-ß Glycyrrhetinic Acid Phytosome®) (GP) and evaluation of their application properties and real-time physical stability. Phytosomes incorporation did not significantly affect pH of the hydrogels, which was acceptable for cutaneous application. However, these hydrogels had significantly different organoleptic properties (opaque and softer consistency) compared to the hydrogel without active substance (C) and the hydrogels with pure active substances (E and G) used for comparison. The values of maximum and minimum apparent viscosity and yield stress were significantly lower in phytosome-loaded hydrogels. The results of oscillatory rheological analysis indicated that viscous character prevails in EP and GP hydrogels (elastic modulus (G')˂viscous modulus (G")), while in hydrogels C, E and G elastic properties were more pronounced (G'˃G"). Escin phytosome had greater influence on carbomer gel network strength. Phytosome-loaded hydrogels were physically stable during 24 months of storage under ambient conditions, although the rheological analysis also indicated a potential risk of sedimentation.

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Signatures of physical aging and thixotropy in aqueous dispersion of Carbopol

Cited by 36 publications

References 82 publications

Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type

Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type

An alternative approach for measuring yield stress and its application in Carbopol microgel

Rheological behavior study and its significance in the assessment of application properties and physical stability of phytosome loaded hydrogels

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