Characterization of starch and its mono and hybrid derivatives by thermal analysis and FT-IR spectroscopy

Carboxymethylation of wheat starch and alpha-cyclodextrin followed by ultrasonic treatment of carboxymethyl wheat starch afforded starch derivatives differing in molecular size. Their degree of substitution was estimated to be 0.6. Starch materials were further sulfated to give hybrid derivatives with carboxymethyl and sulfate groups. A series of wheat starch and alpha-cyclodextrin derivatives were characterized by FT-IR spectroscopy and thermogravimetric analysis. Thermal analysis of starch and their derivatives revealed information concerning their thermal stability and decomposition. It has been found that carboxymethylation and sulfation decrease the thermal stability of starch materials. Similarly, their hybrid carboxymethyl-sulfate derivatives showed the same effect. Further, it has been found that the thermal stability of cyclic molecules was higher in comparison with linear ones.