Rheological Properties of the L Phase and the Hexagonal, Lamellar, and Cubic Liquid Crystals of the CTAB/Benzyl Alcohol/Water System

Montalvo, Gemma; Valiente, Mercedes; Rodenas, E.

doi:10.1021/la9515682

Cited by 144 publications

(110 citation statements)

References 26 publications

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“…Bicontinuous cubic liquid crystals have been reported to exhibit a viscoelastic spectrum similar to that described above for the I 1 ' mesophase (Radiman et al, 1994), (Montalvo et al, 1996). Their viscoelastic spectrum fit the Maxwell model, with a single relaxation time, or the Generalized Maxwell model with only two relaxation times.…”

Section: Hexagonal Liquid Crystals (H 1 ) (H 2 )mentioning

confidence: 56%

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Rheological and phase behaviour of amphiphilic lipids

Muñoz

Alfaro

2000

Grasas y Aceites

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RESUMEN Comportamiento reológico y de fase de lípidos anfifílicosEn este capítulo se realiza una revisión de las distintas estructuras coloidales de asociación que pueden formar los lípidos anfifílicos en estado líquido-cristalino y de sus correspondientes propiedades de flujo en cizalla. Se describe la estructura y comportamiento reológico de cristales líquidos termotrópicos, con énfasis en los de tipo esméctico, fases gel, y cristales líquidos liotrópicos: nemáticos, laminares, laminares diluidos, dispersiones de laminares, hexagonales y cúbicos. Se hace hincapié en la importancia de una buena caracterización reológica y reo-óptica de cara a sus aplicaciones prácticas, desarrollo de formulaciones y como una técnica útil para determinar diagramas de fases y detectar cambios de estructura. Se ha usado una metodología histórica para analizar la evolución de la caracterización reológica e identificación de las diferentes estructuras líquido-cristalinas y estructuras afines. La interpretación de comportamientos de flujo viscoso no newtonianos, fenómenos tixotrópicos y antitixotrópicos y de las propiedades viscoelásticas lineales, determinadas con ensayos dinámicos y de fluencia, y no lineales, descritas mediante la diferencia de esfuerzos normales y ensayos de relajación del esfuerzo, se basa en la interrelación microestructuracomportamiento reológico. La naturaleza policristalina de los cristales líquidos resulta ser muy sensible a la cizalla, debido al cambio de tamaño y orientación de los dominios líquido-cristalinos mientras fluyen. PALABRAS-CLAVE: Comportamiento de fase Comportamiento reológico Lípidos anfifílicos. SUMMARY Rheological and phase behaviour of amphiphilic lipidsThis chapter reviews the different association structures which are likely to be formed by amphiphilic lipids in the liquid-crystalline state and their corresponding shear flow properties. The structure and rheological behaviour of thermotropic liquid crystals, emphasizing the properties of smectic mesophases, and those of lyotropic liquid crystals such as: nematic, lamellar, diluted lamellar, lamellar dispersions, hexagonal and cubic mesophases are described. The importance of a comprehensive rheological characterisation, including rheo-optical techniques, is pointed out for their practical applications, development of formulations and as a useful technique to assist in the determination of phase diagrams. A historical approach has been used to discuss the evolving field of the rheology and structure identification of liquid crystals formed by amphiphilic lipids and surfactants. Non-Newtonian viscous shear flow, thixotropic and antithixotropic phenomena, linear viscoelastic properties -described by dynamic and creep compliance experiments-and non-linear viscoelastic properties -described by the difference of normal stresses and stress relaxation tests are interpreted on the basis of a microstructure-rheology relationship. The polycrystalline nature of liquid crystals turns out to be rather sensitive to shear due to the change of both size...

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Section: Hexagonal Liquid Crystals (H 1 ) (H 2 )mentioning

confidence: 56%

“…Viscosities of the lamellar mesophase formed in a ternary cationic surfactant/aromatic alcohol/water system were shown to increase with surfactant concentration, although this effect clearly vanished with increasing shear rates (Montalvo et al, 1996).…”

Section: Rheology Of Lamellar Liquid Crystals (L α α )mentioning

confidence: 96%

Rheological and phase behaviour of amphiphilic lipids

Muñoz

Alfaro

2000

Grasas y Aceites

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“…Recent studies Refs. [26,27] have reported that frequency scans for a hexagonal phase all follow the same general trend that is: G exceeds G at low frequency; at higher frequencies G and G intersect at a characteristic frequency whose reciprocal corresponds to the main relaxation time (of the order of seconds) and above this cross over frequency the phase has a predominantly elastic response. This behaviour corresponds to the transition to the flow region expected by the Maxwell model (Eq.…”

Section: Hexagonal Liquid Crystalline Phasementioning

confidence: 84%

Shear rheology and phase behaviour of sodium oleate/water mixtures

Antunes

Coppola

Gaudio

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of shear-rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30 wt.% NaO and within the temperature range 5-70 • C).Steady shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the shear flow showed: (1) a structural evolution into the liquid micellar phase (L 1 ) as a function of composition and (2) the presence of a viscous micellar region (L * 1 ) induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H 1 ) were studied by linear shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H 1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between rheology and microstructural changes was conducted by the "weak-gel" model.

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“…Modeling of the viscoelastic properties The viscoelastic properties of the samples can be described by either using a generalized Maxwell model (Montalvo et al 1996;Steffe 1996;Subramanian and Gunasekharan 1997;Rao 1999;Ak and Gunesekharan 2001;Cuppola et al 2004) or by using power law relationship (Ortega-Ojeda et al 2004a, b, 2005Nishinari 2007). Maxwell model consists of a spring to represent the elastic and dashpot to represent the viscous nature of the viscoelastic materials connected in series.…”

Section: Dynamic Rheological Propertiesmentioning

confidence: 99%

“…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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Rheological Properties of the L Phase and the Hexagonal, Lamellar, and Cubic Liquid Crystals of the CTAB/Benzyl Alcohol/Water System

Cited by 144 publications

References 26 publications

Rheological and phase behaviour of amphiphilic lipids

Rheological and phase behaviour of amphiphilic lipids

Shear rheology and phase behaviour of sodium oleate/water mixtures

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

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