Bioderived "Green" Composite from Soy Protein and Eggshell Nanopowder

A bioderived and ecofriendly hybrid nanocomposite was developed from soy protein and eggshell nanopowder (ESNP). ESNP was synthesized via size reduction of chicken eggshells using ball milling followed by a sonochemical process. Transmission electron microscopy and X-ray diffraction (XRD) studies revealed calcite particles in ESNP with sizes ranging between 20 and 40 nm. A trace of protein with the as-synthesized ESNP was detected through X-ray photon spectroscopy (XPS) observation. Dispersion of ESNP in water was achieved by using a polyanionic dispersant via an adsorption mechanism. Green nanocomposites were developed from soy protein isolate (SPI) and dispersed ESNP using glycerol, a natural plasticizer, by a solution casting process. Significant improvements in Young's modulus, tensile strength, and thermal stability of SPI nanocomposite sheets were achieved as a result of incorporation of well-dispersed ESNP. The developed ESNP-incorporated SPI nanocomposite would be inexpensive and useful to fabricate sustainable "green" composite structures.