Effect of Chemical Structures of Polyols on Microstructures, Plasticizing Effectiveness, and Thermal Properties of Potato Starch Film

Abstract

ABSTRACT Various polyols have been evaluated as plasticizers for starch films. However, the influence of their chemical structures on plasticizing effectiveness and thermal properties remains incompletely understood. A jigsaw puzzle defect is how the chemical structures of variations of polyols, such as the position of hydroxyl groups (–OH) along the polyol chain and the presence of linear versus ring structures, affect the performance of starch materials. In this study, two groups of polyols with distinct isomeric structures were selected as model compounds: (1) di‐alcohol pentanediols with varying positions of –OH on the carbon chain; and (2) hexanols featuring linear and various ring structures. The results showed that different pentanediols exhibited lower plasticizing efficiency, due to their longer alkyl chain (–R), whereas sorbitol, characterized by multiple –OH and a flexible linear structure, demonstrated superior plasticizing efficiency. These polyols did not affect the gelatinization temperature of starch, as water remained the primary factor influencing this process. However, the addition of polyols results in a decrease in both the glass transition temperature and crystallinity of starch, indicating more effective disruption of the rigid crystalline regions within the starch matrix. Low‐field nuclear magnetic resonance (LF‐NMR) relaxometry confirmed that in multiplasticizer systems, water protons interacted not only with –OH in starch but also with those in the polyols. This study enhances the understanding of plasticization in hydroxyl‐containing polymers and provides valuable insights for developing starch‐based materials.