Presentation Title

Rheological Behavior and Modelling of Hydrophobically-Modified Gelling Agents Used in Pharmaceutical Semi-Solids

Speaker Credentials

Ph.D. in Pharmacy

College

College of Pharmacy

Location

Nova Southeastern University, Davie, Florida, USA

Format

Poster

Start Date

16-2-2018 12:15 PM

End Date

16-2-2018 1:15 PM

Abstract

Rheological Behavior and Modelling of Hydrophobically-Modified Gelling Agents Used in Pharmaceutical Semi-Solids Samaneh Alaei, Rand Ahmad, Hamid Omidian, PhD College of Pharmacy Nova Southeastern University Objective: The objective was to study the effect of concentration on the rheological behavior of hydrophobically-modified polyacrylic acid polymers and fitness to two rheological models for non-linear flow. Background: Carbomer copolymer type B and carbomer interpolymer type A are polyacrylic acid polymers, modified with a long alkyl chain. Our previous studies showed non-linear rheological behavior for these polymers. There are two models commonly used to describe materials with yield stress and non-linear flow; the Herschel-Bulkley and Casson models, with the Casson being pertinent to systems tending to form aggregates. Methods: Samples were prepared in water at different concentrations ranging from 0.1-1.0% w/w. Following neutralization with NaOH (pH 5.0-6.0), the rheological behavior of the samples was examined using a cone and plate rheometer, and the two models were evaluated for their confidence of fit (COF) to the experimental results. Results: Herschel-Bulkley model fitted all the samples with COF >99.5%, except for 1.0% w/w concentration, which was best fit with Casson model (COF of 100% and 96% for the copolymer and interpolymer, respectively). Shear thinning behavior was presented in the viscosity/shear rate plots, and yield stress values ranged from 85-1538(D/cm2) for copolymer and 46-1967(D/cm2) for the interpolymer. Conclusion: The rheological behavior of hydrophobically-modified carbomers is affected by their solution concentration. At low concentrations, the materials are soluble, thus best fitting Herschel-Bulkley model. At high concentrations and due to lower solubility of the hydrophobic moieties, particles tend to aggregate and fit the Casson model. Grants: This study was supported by NSU Grant 335081.

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Feb 16th, 12:15 PM Feb 16th, 1:15 PM

Rheological Behavior and Modelling of Hydrophobically-Modified Gelling Agents Used in Pharmaceutical Semi-Solids

Nova Southeastern University, Davie, Florida, USA

Rheological Behavior and Modelling of Hydrophobically-Modified Gelling Agents Used in Pharmaceutical Semi-Solids Samaneh Alaei, Rand Ahmad, Hamid Omidian, PhD College of Pharmacy Nova Southeastern University Objective: The objective was to study the effect of concentration on the rheological behavior of hydrophobically-modified polyacrylic acid polymers and fitness to two rheological models for non-linear flow. Background: Carbomer copolymer type B and carbomer interpolymer type A are polyacrylic acid polymers, modified with a long alkyl chain. Our previous studies showed non-linear rheological behavior for these polymers. There are two models commonly used to describe materials with yield stress and non-linear flow; the Herschel-Bulkley and Casson models, with the Casson being pertinent to systems tending to form aggregates. Methods: Samples were prepared in water at different concentrations ranging from 0.1-1.0% w/w. Following neutralization with NaOH (pH 5.0-6.0), the rheological behavior of the samples was examined using a cone and plate rheometer, and the two models were evaluated for their confidence of fit (COF) to the experimental results. Results: Herschel-Bulkley model fitted all the samples with COF >99.5%, except for 1.0% w/w concentration, which was best fit with Casson model (COF of 100% and 96% for the copolymer and interpolymer, respectively). Shear thinning behavior was presented in the viscosity/shear rate plots, and yield stress values ranged from 85-1538(D/cm2) for copolymer and 46-1967(D/cm2) for the interpolymer. Conclusion: The rheological behavior of hydrophobically-modified carbomers is affected by their solution concentration. At low concentrations, the materials are soluble, thus best fitting Herschel-Bulkley model. At high concentrations and due to lower solubility of the hydrophobic moieties, particles tend to aggregate and fit the Casson model. Grants: This study was supported by NSU Grant 335081.