Thermal stability of starch benzoate

Starch esterification with benzoyl chloride was performed in two steps, the first being the alkali treatment of the starch and the second, esterification. Samples of hydrophobic starch benzoate were synthesized with degrees of substitution: 0.73, 1.18 and 1.76 and their thermal stability was investigated by non-oxidative, non-isothermal thermogravimetry. It was shown that starch benzoate was thermally less stable than native starch, the thermal stability decreasing with increasing degree of substitution. The results indicated that the scission of CO2 and/or benzoyl groups probably occurred in the temperature region 100-260 °C, depending on the degree of substitution. The overall activation energies of thermal degradation were calculated by the Flynn-Wall method.