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Low frequency dielectric investigations into the relaxation behavior of frozen polyvinylpyrrolidone-water systems

Barker, S.A., He, R., Craig, D.Q.M. (2001) Low frequency dielectric investigations into the relaxation behavior of frozen polyvinylpyrrolidone-water systems. Journal of Pharmaceutical Sciences, 90 (2). pp. 157-164. ISSN 0022-3549. (doi:10.1002/1520-6017(200102)90:2<157::AID-JPS6>3.0.CO;2-C) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:78869)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
https://doi.org/10.1002/1520-6017(200102)90:2<157:...

Abstract

The low frequency dielectric response of aqueous solutions containing 0, 1, 5, and 10% w/v polyvinylpyrrolidone (PVP) was studied to characterize the low temperature relaxation behavior of these systems. Complementary modulated temperature differential scanning calorimetry (MTDSC) studies allowed measurement of the glass transition temperature for these materials, corresponding to the behavior of the nonfrozen phase. Dielectric investigations in the frequency range of 106 to 10−2 Hz were performed on the systems in the liquid state, with a Maxwell–Wagner response noted for both the PVP solutions and water. The solid-phase responses were studied over a range of temperatures down to − 70°C, with a relaxation peak observed for the PVP systems in the kilohertz region. The spectra were modeled using the Havriliak–Negami equation and the corresponding relaxation times were calculated, with a satisfactory fit to the Arrhenius equation noted. The calculated activation energies were similar to literature values for the dielectric relaxation of water. It is suggested that the dielectric response is primarily a reflection of the relaxation behavior of the water molecules in the nonfrozen fraction, thereby indicating that the dielectric technique may yield insights into specific components of frozen aqueous systems.

Item Type: Article
DOI/Identification number: 10.1002/1520-6017(200102)90:2<157::AID-JPS6>3.0.CO;2-C
Uncontrolled keywords: Amorphous, Dielectric, Freeze drying, Glass, Modulated temperature differential scanning calorimetry (MTDSC), Polyvinylpyrrolidone (PVP), Relaxation, glass, povidone, aqueous solution, article, calculation, dielectric constant, differential scanning calorimetry, freeze drying, heat, liquid, low temperature, solid state
Divisions: Faculties > Sciences > Medway School of Pharmacy
Depositing User: Susan Barker
Date Deposited: 27 Nov 2019 13:13 UTC
Last Modified: 27 Nov 2019 13:13 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/78869 (The current URI for this page, for reference purposes)
Barker, S.A.: https://orcid.org/0000-0003-4880-0253
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