Surface characterization of biodegradable nanocomposites by dynamic speckle analysis

Starch/kefiran/ZnO nanocomposite films may exhibit different physicochemical properties depending on the distribution of ZnO nanoparticles. As a result of UV exposure, the hydrophobicity of the nanoparticles may be modified, resulting in their dispersion in the polymer matrix. The aim of this paper is to characterize starch/kefiran/ZnO nanocomposite films using dynamic speckle analysis. In this experiment, speckle patterns of the nanocomposite are acquired in situ under controlled moisture, pressure, and temperature conditions. This is followed by a statistical postprocessing procedure to determine the deformation pattern of the nanocomposite. A numerical analysis of the successive speckle patterns is used to determine the time evolution of sample deformation. There is a correlation between the intensity and contrast of speckle patterns and the temporal alteration of the polymer. Several factors have been considered to examine the structural evolution of the nanocomposite, including time history speckle pattern, co-occurrence, graphical speckle contrast, roughness parameter, auto-correlation, and Shannon entropy. The variation and overall viscoelastic properties of the nanocomposites are expressed via several statistical parameters. The changes in the computed parameters are attributed to the time-varying activity of the samples during their higher hydrophilicity.