Kinetics, Thermodynamics and Structure: An Analysis of Corn Starch Acetylation

Author(s)

Roberta Ranielle Matos de Freitas ; Karina Palmizani do Carmo ; Franciane Andrade de Pádua ^[3] ; Vagner Roberto Botaro

• Document type: Journal article
• Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 28, 2025-03-03.

Abstract

This study investigated the kinetics and thermodynamics of starch acetylation and examined the influence of the degree of substitution (DS) on the properties of acetylated starches. Starch acetylation kinetics followed a pseudo-first-order model, reaching a degree of substitution of 2.62 after 50 minutes. Negative enthalpy and entropy values revealed a non-spontaneous reaction requiring catalysis. Fourier Transform Infrared Spectroscopy confirmed acetylation through the appearance of a carbonyl band and the reduction of the glycosidic bond peak. Increasing degree of substitution caused granule breakage, agglutination, and reduced crystallinity, as evidenced by Scanning Electron Microscopy and X-Ray Diffraction. Dynamic Mechanical Analysis demonstrated that these structural changes reduced the glass transition in high degrees of substitution (DS 2.62) and enhanced thermal stability and viscoelastic properties due to the loss of crystallinity. Understanding these processes facilitates the industrial optimization of starch acetylation, resulting in modified starches with improved properties for diverse applications. (AU)

• FAPESP's process: 16/19896-2 - Study of dynamic thermal-mechanical behavior of polymeric hydrogels films for application as future biocompatible materials
• Grantee: Vagner Roberto Botaro
• Support Opportunities: Regular Research Grants