Molecular motions in chitosan studied by dielectric relaxation spectroscopy

M. Teresa Viciosa, Madalena Dionísio, Ricardo M. P. da Silva, R. L. Reis, João F. Mano

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)

Abstract

Neutralized and nonneutralized chitosan films subject to different thermal treatments were studied by dielectric relaxation spectroscopy from -130 to +150 °C in the frequency range between 20 Hz and 1 MHz. Two main relaxation processes, both arrhenian type, were detected: process I at temperatures below 0 °C with a mean activation energy of 49 ± 1 kJ mol-1, which has the characteristics of a secondary relaxation process related with local chain dynamics, and process II observable at higher temperatures with an activation energy of 94 ± 2 kJ mol-1, correlated with dc conductivity, which is found in dried polysaccharides systems. Process I is always observed in neutralized chitosan, but it is strongly depleted in the wet nonneutralized form. Although the location of process I is independent of NH2/NH3+ side group, process II deviates to higher temperatures with dryness in both chitosan forms, being located at lower temperatures in nonneutralized chitosan.

Original languageEnglish
Pages (from-to)2073-2078
Number of pages6
JournalBiomacromolecules
Volume5
Issue number5
DOIs
Publication statusPublished - Sep 2004

Keywords

  • Activation energy
  • Carbohydrates
  • Insulators
  • Biopolymers
  • Electrical conductivity

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