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Effects of moisture content on structural and dielectric properties of cassava starch films
Author(s) -
Bergo Paulo,
Moraes Isabel C. Freitas,
Sobral Paulo J. do Amaral
Publication year - 2012
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.201200023
Subject(s) - dielectric , water content , fourier transform infrared spectroscopy , gravimetric analysis , materials science , moisture , bound water , chemical engineering , infrared spectroscopy , starch , analytical chemistry (journal) , molecule , composite material , chemistry , organic chemistry , geology , geotechnical engineering , optoelectronics , engineering
In this work, it was evaluated the effect of moisture content on the structural and dielectric properties of cassava starch films by means of Fourier Transform infrared spectroscopy (FTIR), impedancimetric, and gravimetric analysis. The film samples were equilibrated in hermetically sealed desiccators, containing different saturated salts in water in order to promote activity of water between 0.11 and 0.85. The position and amplitude of the peaks in the “fingerprint” region of the FTIR spectra were changed due to the modifications in the interactions between the polymeric chains and water molecules. These effects may be related to the formation of semi‐crystalline regions in the film structure. The dielectric properties of the films were also strongly dependent on the moisture content, showing a non‐linear and a linear region, which was attributed to the domain of bound and free water in the film, respectively. The gravimetric analyzes showed the typical sigmoidal behavior, attributed to the way the water interacts with the biopolymer. Finally, the flexibility of the films increased with water content increasing.