Abstract:Owing to its non-toxicity, excellent biodegradability, film-forming property, and biocompatibility, sodium alginate (SA) is used as a common and promising raw material for biopolymer films. However, pure SA films tend to have defects in performance and functionality; therefore, blend films, consisting of two or more types of components, are more widely used as precursors for biopolymer films. To investigate the synergy between SA and Enteromorpha polysaccharide (EP), a degradable composite film was fabricated by blending SA and EP with glycerol as a plasticizer. The effect of different polysaccharide mass ratios, total mixed solution concentrations, and glycerol contents on the tensile strength, elongation at break, water vapor permeation, and water solubility of the films was investigated. In addition, the microstructure of the films was characterized through Fourier transform infrared spectroscopy and scanning electron microscopy. Results showed a good compatibility and synergy between SA and EP. Moreover, no obvious phase separation was observed in all SA/EP composite films. The component mass ratio, total concentration, and glycerol content had a significant influence on the properties of composite films. Among these factors, mass ratio had the most significant influence on the films. The addition of an appropriate amount of EP improved the tensile strength and elongation at break of the SA film and reduced its water vapor transmission rate; however, it slightly increased the water solubility of the SA/EP composite film. When the component mass ratio was modified from 10:0 to 8:2, the tensile strength increased from 99.22 MPa to 108.41 MPa, the elongation at break increased from 5.14% to 6.20%, and the water vapor transmission rate decreased from 6.445×10–11 g/(m·s·Pa) to 6.027×10–11 g/(m·s·Pa), which were the comprehensive optimal mechanical and barrier properties of the films. The total concentration and glycerol content of the SA/EP composite films were further optimized. The best total concentration and glycerol content were 1.6% (m/v) and 0.9% (m/v), respectively. The results demonstrate that the addition of EP enhanced the mechanical and barrier properties of the SA films and that there is a relatively strong synergistic effect between SA and EP.
