Abstract: In order to improve the properties of collagen films, based on the electrostatic interaction between electronegative sodium polyacrylate and electropositive turgid collagen fibers, we evaluated the impact of adding different amounts of sodium polyacrylate (0.1%–1.0%) on membrane properties. The results showed that Zeta potential of the film-forming suspension significantly changed with the increase of sodium polyacrylate concentration (P < 0.05) suggesting enhanced electrostatic interaction. Sodium polyacrylate addition decreased the elongation at break, light transparency and water vapor permeability (the minimum value reached 1.30 × 10-12 g/(cm?s?Pa)) of the films and increased the thermal stability (up to 1.50 folds higher than that of pure films), but it had no impact on film thickness. Scanning electron microscopic analysis showed that the composite films were more compact. Addition of 0.3% sodium polyacrylate showed better film properties: tensile strength, elongation at break, light transparency and water vapor permeability were 37.60 MPa, 14.20%, 48.70% and 1.30 × 10-12 g/(cm?s?Pa), respectively. In addition, the conformational changes of the composite films were confirmed by Fourier transform infrared spectroscopy. The enhanced effect of sodium polyacrylate and collagen due to electrostatic interaction showed that appropriate addition of sodium polyacrylate could effectively improve collagen membrane properties.

Key words: collagen, sodium polyacrylate, electrostatic interaction, properties, edible films