Non-conventional characterization of the elastic properties of starch films reinforced with micro- and nano-silica particles

This study highlights the effectiveness of laser vibrometry as a novel non-destructive technique for characterizing the local mechanical properties of biopolymer composites. In this work, was explored the influence of silica micro- and nano-particles derived from rice husk on the dynamic mechanical properties of biodegradable corn-starch films. Films were fabricated using solvent-casting and characterized using various techniques, including laser vibrometry, to assess the local Dynamic Elastic Modulus ( E dyn ). Results showed that the incorporation of silica particles, particularly at 1%, significantly enhanced the E dyn of the films. Scanning Electron Microscopy (SEM) revealed an inhomogeneous distribution of silica particles, resulting in regions with Dynamic Elastic Modulus values comparable to the pristine film and regions with significantly higher E dyn . Micro-silica particles demonstrated a more pronounced increase in Dynamic Elastic Modulus than nano-particles due to their lower surface area and reduced agglomeration. Interestingly, higher silica concentrations (3%) decreased E dyn , likely due to particle agglomeration and exceeding the percolation limit. This study highlights the effectiveness of laser vibrometry as a novel technique for characterizing the local mechanical properties of biopolymer composites, offering valuable insights into their inhomogeneous microstructures.