Abstract

AYALA, GERMÁN; AGUDELO, ANA  and  VARGAS, RUBÉN. EFFECT OF GLYCEROL ON THE ELECTRICAL PROPERTIES AND PHASE BEHAVIOR OF CASSAVA STARCH BIOPOLYMERS. Dyna rev.fac.nac.minas [online]. 2012, vol.79, n.171, pp.138-147. ISSN 0012-7353.

Films of different concentrations of glycerol/starch (G/S) blends were prepared and analyzed by impedance spectroscopy (IS), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The dc-conductivity of the films increases by increasing both the glycerol content and temperature. A power-law dispersive behavior of the frequency-dependent conductivity at high frequencies has been observed in all G/S films in the blend compositions prepared, similar to that observed in other solid ionic conductors and known as a "universal dynamic response." The electrical conductivity enhancement is consistent with the subtle changes in the -OH glycerol groups coordination with the starch chains introduced by increasing the glycerol content and temperature. A stable single phase is revealed under the electrical measurement conditions up to approximately 100 °C for all concentrations, but the stability can be maintained up to higher temperatures (∼150 °C) at glycerol concentrations below G/S = 0.4.

Keywords : cassava starch; glycerol; electrical conductivity; phase behavior.

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