Preparation, characterization, and application of soy protein isolate/Mg–Al layered double hydroxide-based bionanocomposite films

Soy protein isolate has received much attention in recent decades due to its abundance, eco-friendliness, low cost, film-forming capacity, and processability. In this study, novel soy protein isolate (SPI)-based bionanocomposite films were prepared by integrating Mg–Allayered double hydroxide (LDH) at different loadings (0%, 2%, 5%, and 9% w/w) using a simple solution casting process. The Mg–Al LDH was synthesized in a 2:1 molar ratio via a co-precipitation method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy, and thermogravimetric analysis (TGA) revealed intercalation/exfoliation of Mg–Al LDH sheets in the SPI matrix of bionanocomposite films. Agglomeration of Mg–Al LDH was distinctly noticed as its concentration increased from 0 to 9% (w/w). The bionanocomposite films showed considerable thermal stability. Mechanical and biodegradation qualities were also investigated. The tensile strength values of the prepared films with 0%, 2%, 5%, and 9% w/w LDH loadings were found to be 2.12 ± 0.25, 1.60 ± 0.15, 1.64 ± 0.08 and 1.58 ± 0.06 KNm/g, respectively. The SPI-Mg/Al LDH 5% film showed a substantial increase in tensile strength and efficiently degraded in non-sterile soil.