Utilize este identificador para referenciar este registo:
https://hdl.handle.net/1822/4025
Título: | Molecular motions in chitosan studied by dielectric Relaxation spectroscopy |
Autor(es): | Viciosa, M. T. Dionísio, M. Silva, R. M. Reis, R. L. Mano, J. F. |
Data: | 2004 |
Editora: | ACS Publications |
Revista: | Biomacromolecules |
Citação: | "Biomacromolecules". ISSN 1525-4497. 5:5 (Sept. 2004) 2073-2078. |
Resumo(s): | 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. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/4025 |
DOI: | 10.1021/bm049685b |
ISSN: | 1525-4497 |
Arbitragem científica: | yes |
Acesso: | Acesso aberto |
Aparece nas coleções: | 3B’s - Artigos em revistas/Papers in scientific journals |