Structural changes in CTAB/H2O mixtures using a rheological approach

Coppola, Luigi; Gianferri, Raffaella; Nicotera, Isabella; Oliviero, Cesare; Ranieri, Giuseppe Antonio

doi:10.1039/b316621j

Cited by 80 publications

(79 citation statements)

References 32 publications

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“…However, three different theories were needed: the cooperative flow model from Bohlin, 35 the soft glass rheology (SGR) model for soft materials, 36,37 and the slip plane theory for cubic phases. 38 These models have been used previously in several studies regarding the rheology of cubic and hexagonal phases and based gel emulsions 4,17,39 and for gels formed with different surfactants, 40,41 so they seemed appropriate to be used in the present system. 35 to explain the flow character and microstructure of a flowing substance by means of rheological data.…”

Section: Modeling the Viscoelastic Parametersmentioning

confidence: 99%

“…The values for the normal hexagonal phase (H 1 ) vary considerably from ~3, to 9.5, in different systems. 15,17,40 The values for H 2 are reported 17 as ~ 6.7. The main cause of this mismatch could be that in all of the systems studied there was no crossover between G' and G'', since the samples were gel-type.…”

Section: Theory Of Cooperative Flow This Theory Was Presented By Bohlinmentioning

confidence: 99%

“…However, this theory has been applied in many systems 34,42 in which G'>>G'' in all the frequency range. This theory has been used to determine the interaction among aggregates and crystalline domains in hexagonal liquid crystals with non-ionic surfactants and block copolymers 17,34 , in reverse hexagonal liquid crystals with block copolymers 17 , in CTAB/water mixtures 40 and also in food preparations like jam or yoghurt 42 . The values for the normal hexagonal phase (H 1 ) vary considerably from ~3, to 9.5, in different systems.…”

Section: Theory Of Cooperative Flow This Theory Was Presented By Bohlinmentioning

confidence: 99%

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Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer

2011

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This article reports the phase behavior determination of a system forming reverse liquid crystals, and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural properties. This system forms reverse cubic (I 2 ) and reverse hexagonal (H 2 ) phases at high polymer concentrations. These reverse phases are of particular interest, since in the two-phase region, stable high internal phase reverse emulsions can be formed. The characterization of Published in: Langmuir, February 2, 2011, Volume 27, Number 6, Pages 2286-2298 the I 2 and H 2 phases and of the derived gel emulsions was performed with small-angle X-ray scattering (SAXS) and rheometry, and the influence of temperature and water content was studied. The H 2 phase experimented a thermal transition to an I 2 phase when temperature was increased, which presented an Fd3m structure. All samples showed a strong shear thinning behavior from low shear rates. The elastic modulus (G') in the I 2 phase was around one order of magnitude higher than in the H 2 phase. G' was predominantly higher than the viscous modulus (G''). In the gel emulsions, G' was nearly frequencyindependent, indicating their gel type nature. Contrarily to water-in-oil (W/O) normal emulsions, in W/I 2 and W/H 2 gel emulsions, G', the complex viscosity (|*|) and the yield stress ( 0 ) decreased with increasing water content, since the highly viscous microstructure of the continuous phase was responsible for the high viscosity and elastic behavior of the emulsions, instead of the volume fraction of dispersed phase and droplet size. A rheological analysis, in which the cooperative flow theory, the soft glass rheology model and the slip plane model were analyzed and compared, was performed to obtain one single model that could describe the non-Maxwellian behavior of both reverse phases and highly-concentrated emulsions and to characterize their microstructure with the rheological properties.

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Section: Modeling the Viscoelastic Parametersmentioning

confidence: 99%

Section: Theory Of Cooperative Flow This Theory Was Presented By Bohlinmentioning

confidence: 99%

Section: Theory Of Cooperative Flow This Theory Was Presented By Bohlinmentioning

confidence: 99%

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Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer

2011

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“…Starch when heated in the presence of excess water undergoes gelatinization which involves granule swelling, amylose leaching and amylopectin fusion and upon cooling due to retrogradation, solubilized starch forms a viscous dispersion or paste or gel depending on the temperature of processing and concentration of dispersion, varieties, harvesting age and growth season Asaoka et al , 1992Defloor et al 1998;Lagarigue and Alvarez 2001;Moorthy 2001;Fourmann et al 2003). The viscoelastic behavior of starchy food systems is characterized by dynamic rheological tests and can be evaluated by Maxwell and power law models (Montalvo et al 1996;Steffe 1996;Subramanian and Gunasekharan 1997;Cortes et al 1999;Rao 1999;Ak and Gunesekharan 2001;Acharya et al 2004;Cuppola et al 2004;Ortega-Ojeda et al 2004a, b, 2005Nishinari 2007). Reports on the application of these models to quantify the viscoelastic behavior of gelated cassava starch dispersion are scanty.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of thermal softening of cassava tubers and rheological modeling of the starch

et al. 2010

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Cassava or tapioca (Manihot esculenta Crantz) tubers having high amount of carbohydrate are utilized after boiling or processing into starch and flour. Textural properties of raw and cooked tubers depend on variety, maturity, growing environment, physico-chemical and starch properties. Starch is used in food preparations as gelling and thickening agent, stabilizer and texture modifier. This study aims at analyzing and modeling the textural, dynamic rheological and gelatinization properties of selected cassava varieties. The thermal softening behavior was analyzed by linear regression and fractional conversion techniques, rheological properties of the gelated starch by Maxwell and power law models. The varieties were classified based on their physico-chemical, texture profile, rheological and gelatinization properties by multivariate analysis. The textural, rheological and gelatinization properties were significantly affected by the varieties (p<0.05). Thermal softening of tubers was modeled by dual mechanism first order kinetic model with rate constant values ranging from 0.081 to 0.105 min −1 . Linear regression models with extremely good fit were obtained to explain the relationship between the degree of cooking and relative firmness. The dynamic spectra of the gelated starch showed the characteristics of concentrated biopolymer dispersion and described using Maxwell and power law model. The results showed that textural, rheological and gelatinization properties varied considerably among the varieties and besides the physico-chemical properties, interaction between them and structural make up of the tuber parenchyma had a great influence on cooking quality and rheological properties.

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“…The dependence of these quantities on the oscillating frequency gives rise to the socalled mechanical spectrum, allowing the quantitative rheological characterization of studied materials. Weak gel model was applied to some of the oscillatory spectra [34,35]:…”

Section: Methodsmentioning

confidence: 99%

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

Antunes

Coppola

Rossi

et al. 2008

Colloids and Surfaces B: Biointerfaces

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a b s t r a c tVesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (CMC) and hydrophobically modified carboxymethyl cellulose (HMCMC). While the polymer-vesicle association was probed by rheology, the influence of the polymer on the vesicle stability was monitored by cryo-TEM and calorimetric measurements.The effects of the polymer on the rheological properties of surfactant aggregate solutions clearly depend on the polymer type: the storage moduli of the polymer-vesicle mixtures, compared to the vesicles alone, increases around 2 orders of magnitude if the polymer is non-associative and 4 orders of magnitude if the macromolecule is of associative type.As the vesicles are added, the non-associative polymer networks tend to be disrupted, while the networks formed by associative polymer get more robust. These observations can be explained by fundamental changes in electrostatic/hydrophobic interactions: vesicles entrapped in KC networks convert the polysaccharide in a highly charged entity and favor high electrostatic repulsions between the chains; this encourages network collapse. The opposite picture is experienced in HMCMC systems, i.e., such network is stabilized by the presence of vesicles. This is ascribed to the enhanced hydrophobic association, compensating the electrostatic repulsions between vesicles and polymer chains.

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Structural changes in CTAB/H2O mixtures using a rheological approach

Cited by 80 publications

References 32 publications

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer

Kinetics of thermal softening of cassava tubers and rheological modeling of the starch

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

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Structural changes in CTAB/H2O mixtures using a rheological approach

Cited by 80 publications

References 32 publications

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I2 and W/H2 Gel Emulsions Using an Amphiphilic Block Copolymer

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I2 and W/H2 Gel Emulsions Using an Amphiphilic Block Copolymer

Kinetics of thermal softening of cassava tubers and rheological modeling of the starch

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

Contact Info

Product

Resources

About

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer

Phase Behavior and Rheological Analysis of Reverse Liquid Crystals and W/I₂ and W/H₂ Gel Emulsions Using an Amphiphilic Block Copolymer