Mechanochemical effect of starch during the plasticization

Abstract

In this work, a starch-based material was produced by two-rotor continuous mixing extruder. The evolution of the microstructure during the plasticization process of materials was analyzed. The mechanochemical effect on materials’ morphology, molecular structure, crystallinity, and thermal stability were discussed under different rotor speeds. The results showed that starch was completely plasticized in the middle mixing section of the extruder. However, it could be partially degraded in the late mixing section by strong mechanical force under the rotor speed of 500 r/min. Varied levels of mechanical force would lead to the formation of distinct types of process-induced crystalline structures in starch-based materials. Moreover, thermogravimetric analysis indicated that reducing the rotor speed or prolonging the mixing time at low speed were conducive to enhancing the thermal stability of starch-based materials. Specifically, under the rotor speed of 300 r/min, the starch-based material exhibited optimal plasticizing effect and high thermal stability.