Characterization of starch films impregnated with starch nanoparticles prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation

In this work, we investigated the effects of adding different contents (0%, 0.5%, 1%, 2%, 5%, wt% based on maize starch, dsb) of starch nanoparticles prepared by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation (TEMPO-SNPs) on the properties of maize starch films. Differential scanning calorimetry, X-ray diffraction analysis, scanning electron microscopy (SEM), transmission electron microscopy and texture profile analysis were used to characterize the thermal properties, morphology and structure of the prepared films. As the content of TEMPO-SNPs increased, the water vapor permeability (WVP) of films reduced significantly from 4.21 × 10−8 to 3.04 × 10−8 g m−1 s−1 Pa−1. Furthermore, elongation at break, tensile strength and Young's modulus of the films increased as the TEMPO-SNPs content increased. At the TEMPO-SNPs content of 1%, the elongation at break, the tensile strength and Young's modulus of the films peaked. SEM showed that the nanocomposite films had smoother surfaces and cross sections with no cracks or visible air pockets.