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Article

Flow and Thixotropic Parameters for Rheological Characterization of Hydrogels

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Department of Physical and Colloidal Chemistry, Faculty of Pharmacy, University of Medicine and Pharmacy “Carol Davila”, Bucharest 020956, Romania
2
Department of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, University of Medicine and Pharmacy “Carol Davila”, Bucharest 020956, Romania
*
Author to whom correspondence should be addressed.
Academic Editor: Yogeshvar N. Kalia
Molecules 2016, 21(6), 786; https://doi.org/10.3390/molecules21060786
Received: 21 April 2016 / Revised: 6 June 2016 / Accepted: 13 June 2016 / Published: 16 June 2016
(This article belongs to the Special Issue Transdermal Delivery Systems: Current Landscape and Trends)
The goal of this paper was to design several sodium carboxymethylcellulose hydrogels containing a BCS class II model drug and to evaluate their flow and thixotropic properties. The rheological measurements were performed at two temperatures (23 °C and 37 °C), using a rotational viscometer. The hydrogels were stirred at different time intervals (10 s, 2, 5, 10 and 20 min at 23 °C, and 10 s, 2 and 5 min at 37 °C), with a maximum rotational speed of 60 rpm, and the corresponding forward and backward rheograms were recorded as shear stress vs. shear rate. For all hydrogels, the rheological data obtained at both temperatures showed a decrease of viscosity with the increase of the shear rate, highlighting a pseudoplastic behaviour. The flow profiles viscosity vs. shear rate were quantified through power law model, meanwhile the flow curves shear stress vs. shear rate were assessed by applying the Herschel-Bulkley model. The thixotropic character was evaluated through different descriptors: thixotropic area, thixotropic index, thixotropic constant and destructuration thixotropic coefficient. The gel-forming polymer concentration and the rheological experiments temperature significantly influence the flow and thixotropic parameters values of the designed hydrogels. The rheological characteristics described have an impact on the drug release microenvironment and determine the stasis time at the application site. View Full-Text
Keywords: hydrogel; rheological models; flow parameters; thixotropic descriptors hydrogel; rheological models; flow parameters; thixotropic descriptors
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MDPI and ACS Style

Ghica, M.V.; Hîrjău, M.; Lupuleasa, D.; Dinu-Pîrvu, C.-E. Flow and Thixotropic Parameters for Rheological Characterization of Hydrogels. Molecules 2016, 21, 786. https://doi.org/10.3390/molecules21060786

AMA Style

Ghica MV, Hîrjău M, Lupuleasa D, Dinu-Pîrvu C-E. Flow and Thixotropic Parameters for Rheological Characterization of Hydrogels. Molecules. 2016; 21(6):786. https://doi.org/10.3390/molecules21060786

Chicago/Turabian Style

Ghica, Mihaela Violeta, Mircea Hîrjău, Dumitru Lupuleasa, and Cristina-Elena Dinu-Pîrvu. 2016. "Flow and Thixotropic Parameters for Rheological Characterization of Hydrogels" Molecules 21, no. 6: 786. https://doi.org/10.3390/molecules21060786

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