Abstract: A composite film was prepared using corn starch (CS) and eggshell powder (ESP) as the main film-forming substrates. The effects of CS, ESP and glycerol (Gly) concentration on the tensile strength (TS), elongation at break (EB), water vapor permeability (WVP), and oxygen permeability (OP) of CS/ESP film were studied. Principal component analysis method was used to comprehensively evaluate the film properties. The optimum process parameters determined through response surface methodology were as follows: CS 4.9 g/100 mL, glycerol 49%, and ESP 1.9%. The TS, EB, WVP, and OP of the film prepared under the optimized conditions were 4.97 MPa, 109.12%, 1.31 × 10-12 g/(cm·s·Pa) and 1.19 × 10-5 cm3/(m2·d·Pa), respectively. Fourier transform infrared spectroscopic (FTIR) analysis showed that ESP and CS had good compatibility with each other. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) results showed that the addition of ESP improved the crystallinity and thermal stability of CS/ESP film. Scanning electron microscopy (SEM) analysis revealed that the CS/ESP film had a smooth surface and cross-sectional morphology without obvious protrusions and cavities.

Key words: corn starch, eggshell powder, composite film, physical properties, structural characterization