Effects of multiphase transitions and reactive extrusion on in situ thermoplasticization/succination of cassava starch.

In this work, the effects of the multiphase transitions of starch, the screw configuration, and the conditions of reactive extrusion (REX) on the in situ thermoplasticization/succination of cassava starch were studied. Spectroscopic analyses indicated successful esterification during the REX with the appearance of characteristic bands of carbonyl ester groups. After the REX, the starch developed B- and V-type structures, with the OSA starches showing an additional peak at 7.1°. As the degree of substitution increased, a greater number of partially gelatinized granules were embedded in the starch matrix; an additional degradation temperature of 364.5 °C and a lower weight loss at the degradation temperature of the starch were observed. The incorporation of OS groups via REX imparts better thermal stability. The processing conditions helped prepare a thermoplastic-succinate starch in a single step through an environmentally friendly process.