Numéro de la revue: Volume 29 , Numéro 2
Auteurs: Amel Djori * and Nadji Moulai-Mostefa
Materials and Environmental Laboratory,
University of Medea, Ain D’Heb, 26001 Medea, Algeria
ABSTRACT
The present work aimed to realize a complementary characterization of octenyl succinate anhydride-modified waxy maize starch (OSA WM starch) in terms of surface properties, rheology, and thermorheology. Analyses by conductimetry and measurements of surface tension confirmed the amphiphilc character of the modified polysaccharide. The critical concentration of aggregation was found at a value of 0.1%. At this concentration, the measured surface tension was equal to 54.5 mN/m. In parallel, the rheological and thermorheological behaviors of OSA starch were determined. The model of Herschel-Bulkley was utilized for the evaluation of the rheological parameters. Furthermore, the viscoelasticity study showed that the elastic modulus (G’) and the loss modulus (G ») were sensitive to the polymer concentration and are dependent of frequency and strain; the modified polysaccharide exhibited seemingly a solid-like behavior (G’>G »). Measurements in oscillation of the effect of temperature showed that from a critical temperature, the system becomes much more elastic. The great increase in elasticity confirms its thermoreversible behavior.
Keywords:
OSA maxy waize starch, Surface properties, Morphology, Viscoelasticity, Thermorheology.