Mechanically induced changes in amylose structure and effect on thermal behavior in the presence of TiO2 nanoparticles

Abstract

Thermal behavior of amylose/TiO2 films under ultrasonic irradiation was investigated, and the final product of each process was applied to prepare amylose/TiO2 nanocomposite films. The effects of different degradation techniques on thermal behavior, crystallinity, and molecular weight distribution of amylose were surveyed. The evaluations of structural changes and thermal behaviors were performed by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetry analysis, FT-IR spectroscopy, and scanning electron microscopy. The XRD results clarified that the crystalline shape of amylose molecules formed is an A-type crystal due to the sonophotocatalytic processing, while the FT-IR spectra does not approve any chemical change in amylose structure. The DSC data submitted a broad endothermic peak for amylose. In the case of high loading of nanoparticles, the endothermic analysis results and diffraction peaks for the sonophotocatalytic process were not significant. This indicates that the length of amylose chains through the sonophotocatalytic degradation became smaller. An increase at the loading of TiO2 improved the hydrophilic properties of amylose/TiO2 films, which leads to the modification of water absorption behavior. Mechanical properties of amylose/TiO2 films were affected by the uniform dispersion of TiO2 in the polymer matrix.