Characterization of yield stress and slip behaviour of skin/hair care gels using steady flow and LAOS measurements and their correlation with sensorial attributes / S. Ozkan in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 34, N° 2 (04/2012)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 34, N° 2 (04/2012) . - p. 193-201 Titre : Characterization of yield stress and slip behaviour of skin/hair care gels using steady flow and LAOS measurements and their correlation with sensorial attributes Type de document : texte imprimé Auteurs : S. Ozkan, Auteur ; T. W. Gillece, Auteur ; L. Senak, Auteur ; David J. Moore, Auteur Année de publication : 2012 Article en page(s) : p. 193-201 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Acide polyacrylique Analyse sensorielle Caractérisation Copolymères Cosmétiques Epaississants Gels -- Emploi en cosmétologie Maléique, Acide Polyvinyl éther Polyvinylpyrrolidone Rhéologie Tags : 'Gel  main/cheveux'  'Grande  amplitude  oscillatoire'  Rhéologie  'Corrélation  sensorielle'  'Limite  élasticité' Index. décimale : 668.5 Parfums et cosmétiques Résumé : Gels made with three different polymers widely used as rheology modifiers in cosmetic formulations (cross-linked poly(acrylic acid), cross-linked poly(maleic acid-alt-methyl vinyl ether) copolymer and cross-linked poly(acrylic acid-co-vinyl pyrrolidone) copolymer) were characterized by rheological and sensory evaluation methods to determine the relationship between sensorial perception and corresponding rheological parameters. Both conventional rheological characterization methods and a more recent method, Fourier Transform Rheology with Large Amplitude Oscillatory Flow data (LAOS), were utilized to characterize the material with and without wall slip. Sensorial analyses were implemented in vivo to evaluate the perceived ease of initial and rub-out spreadability, cushion, pick-up and slipperiness attributes of the gels. Results were statistically analysed by both variance (ANOVA) and principle component analysis (PCA). Sensorial panel testing characteristics discriminated the three materials, and PCA analyses revealed that sensory attributes could be well predicted by rheological methods. Rheological experiments, without wall slip, revealed that gel strength in the linear viscoelastic region (LVR) and yield stress of these materials are similar, but exhibit significantly different wall slip and thixotropy behaviour in the low shear rate region under wall slip conditions. Above the critical shear rate, which corresponds to the yield stress, all tested materials did not slip and behaved as conventional, shear thinning polymeric fluids. In particular, the rheological parameters and sensorial perception of the 1% cross-linked vinyl pyrrolidone/acrylic acid copolymer were significantly affected by wall slip and/or thixotropy-related shear banding phenomena. Note de contenu : - MATERIALS AND METHODS : Rheological characterization (dynamic oscillatory measurements - Steady torsional flow experiments - Continuous shear rate ramp tests - extensional tests) - Sensory evaluation - Data analysis - RESULTS AND DISCUSSION : Rheological characterization (steady torsional flow experiment - Continuous stress of shear rate ramp measurements to establish the shear rate dependency of shear stress and viscosity at different gap openings - Extensional tests - Sensory evaluation - Correlation of sensory ratings with conventional rheological parameters - Correlation of sensory ratings with large amplitude oscillaroty shear flow (LAOS) parameters (Chebyshev coefficients) DOI : 10.1111/j.1468-2494.2012.00702.x En ligne : https://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2012.00702.x Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=14392 [article]

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Rheological fingerprinting as an effective tool to guide development of personal care formulations / S. Ozkan in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 42, N° 6 (12/2020)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 42, N° 6 (12/2020) . - p. 536-547 Titre : Rheological fingerprinting as an effective tool to guide development of personal care formulations Type de document : document électronique Auteurs : S. Ozkan, Auteur ; C. Alonso, Auteur ; Roger L. McMullen, Auteur Année de publication : 2020 Article en page(s) : p. 536-547 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cheveux -- Soins et hygiène Composés lamellaires Epaississants Formulation (Génie chimique) Gels -- Emploi en cosmétologie Polymères Rhéologie Index. décimale : 668.5 Parfums et cosmétiques Résumé : - Objective : Conventional rheological techniques in the linear viscoelastic region provide insights about the spatial configuration of the microstructural components of personal care formulations in their ‘at‐rest’ state. However, they fail to describe the textural experience associated with large and fast deformations during daily consumer application. In this study we present a non‐conventional rheological technique : large amplitude oscillatory shear (LAOS)—for probing the transformation of a material during its application. This technique is proposed a practical tool for formulators in their efforts to design products with desired textural attributes. - Methods : A non‐linear rheological technique termed LAOS was utilized to capture the textural expression perceived by consumers. Lissajous plots (stress vs. strain or strain rate) provide a fingerprint of the formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry, molecular properties, colloidal parameters and processing conditions. - Results : In this study, we showcased several approaches for modifying the texture of personal care formulations and show the influence of various parameters on the characteristics of the Lissajous curves and their relation to sensorial perception. This fingerprinting technique shows that increasing the molecular weight or hydrophobic modification boosts the elasticity and thickening efficiency of a given polymer. Differences in the chemistry of rheological ingredients also influence the characteristic Lissajous fingerprint. In high concentration surfactant systems, which tend to form worm‐like micelles, their unique Lissajous fingerprints indicate structure rebuild because of fast kinetics at large but slow deformations. Analysis of lamellar gel‐based hair conditioner formulations demonstrates the unique high yield stress of these types of materials, accompanied by the fast breakdown transition from a solid to viscous structure because of their crystalline lamellar gel structure. - Conclusion : The LAOS technique presented in this article is intended to better capture the textural expression perceived by consumers. Lissajous plots—generated from the LAOS experimental data—provide a fingerprint of the tested formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry and molecular weight of the thickener, pH of the formula medium and influence of other ingredients in the formula (surfactants, emulsifiers, etc.). Note de contenu : - Table 1 : Hair conditioner formulations thickened with lamellar gel structure and HMHEC. The pH was adjusted with citric acid - Table 2 : Table 2 DSC data for three formulation prototype hair conditioners : low gel phase without polymer, low gel phase with HMHEC and normal (high) gel phase without polymer - Table 3 : Transparent hair conditioner formulas containing HEC and HPMC as thickening polymers at different pH levels. The pH was adjusted with citric acid. †See text for description En ligne : https://drive.google.com/file/d/1azWiP1_-vXyM6m3kqxntInRFfD5sSeeu/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35419 [article]

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