The effect of nano-SiO2 on the physicochemical and structural properties of gelatin-polyvinyl alcohol composite films

This study investigated the effects of nano-silicon dioxide (nano-SiO2) (0%, 0.5%, 1%, and 1.5%) and the ratio of PVA/gelatin (1: 1 and 2: 1) on the physicochemical and structural properties of gelatin/polyvinyl alcohol composite films. The results showed that the highest value of tensile strength (18.05MPa) was found for a PVA/gelatin ratio of 2: 1 and 1% nano-SiO2 (P2:G1-1%). The films' elongation at break value increased with increases in the nano-SiO2 and PVA content, while their water solubility decreased with the addition of nano-SiO2. Their water vapor permeability decreased with 1% nano-SiO2, and the lowest value for water vapor permeability was with P2: G1-1%. Fourier transform infrared and differential scanning calorimetry results showed that appropriate interaction between both polymers and nano-SiO2 was found with P2: G1-1%. Scanning electron microscopy illustrated a compact structure and good compatibility of nano-SiO2 with gelatin in P1: G1-1% film. X-ray diffraction results showed that the crystallization peak intensity of P2: G1-1% was higher than that of P1: G1-1% nanocomposite films. Overall, the results indicated that the concentration of 1% of nano-SiO2 in P2: G1 films significantly improved the films' physicochemical and structural properties. These results suggest that they could be useful as foodpackaging materials to maintain food quality.