title: Gelatinization and retrogradation phenomena in starch/montmorillonite nanocomposites plasticized with different glycerol/water ratios.
abstract: This study aims to gain insights into the intermolecular interactions present in thermoplastic starch (TPS)/montmorillonite (MMT) nanocomposites prepared using water and/or glycerol as plasticizers. Specifically, the impact of using different glycerol/water proportions on the nature of gelatinization and retrogradation processes is studied. Nanocomposites were characterized by rheometry, scanning electron microscopy (SEM) and X-rays diffraction (XRD). It is shown that clay tactoids preferentially interact with glycerol molecules rather than starch macromolecules. Consequently, the effects of MMT incorporation strongly depend on the glycerol/water ratio; when a ratio of 0.5 is used minor variations were observed on the starch gelatinization process-although stronger clays-starch interactions were evident-whereas at higher ratios the addition of clays significantly increased the gelatinization temperature, up to values over 100°C. In the gelatinization process of starch in TPS samples having only glycerol as a plasticizer, the leaching of amylose and the melting of amylopectin crystalline domains seem to occur simultaneously. This different gelatinization mechanism produces a TPS having a substantially different morphology, which exhibited reduced retrogradation characteristics.
authors.affiliation: Grupo de Diseño de Productos y Procesos (GDPP), Departamento de Ingeniería Química, Universidad de los Andes, Cra 1 N 18A-12, 111711, Bogotá, Colombia. Electronic address: sc.lara61@uniandes.edu.co.
authors.forename: Sandra Camila
authors.initials: SC
authors.lastname: Lara
authors.affiliation: Grupo de Diseño de Productos y Procesos (GDPP), Departamento de Ingeniería Química, Universidad de los Andes, Cra 1 N 18A-12, 111711, Bogotá, Colombia. Electronic address: fesalced@uniandes.edu.co.
authors.forename: Felipe
authors.initials: F
authors.lastname: Salcedo
mesh_terms: D001546:Bentonite; D005990:Glycerol / Q000737:chemistry*; D006358:Hot Temperature; D053761:Nanocomposites / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry*; D013213:Starch; D014867:Water / Q000737:chemistry*
chemical_list: D010968:Plasticizers; D014867:Water; D001546:Bentonite; D013213:Starch; D005990:Glycerol
keywords: Gelatinization; Glycerol/water ratio; Montmorillonite clay; Plasticizers; Retrogradation; Thermoplastic starch