Biopolymer-Based Films from Sodium Alginate and Citrus Pectin Reinforced with SiO2

Blend films based on sodium alginate (SA) and citrus pectin (P) reinforced with different concentrations of SiO2 (0-10% w/w) were developed in this study. From the morphological (SEM) and structural (FT-IR) evaluation, it was verified that the incorporation of the reinforcing agent did not drastically modify the microstructure of the films, nor did new chemical bonds form. However, the XRD results suggested a slight reduction in the crystallinities of the blends by the incorporation of SiO2. Among the formulations prepared, the addition of a 5% reinforcing agent was responsible for the simultaneous improvement of mechanical and barrier properties. Comparing the control sample (SA/P) with the SA/P/5.0%SiO2 film, the tensile strength increased from 27.7 +/- 3.7 to 40.6 +/- 4.5 MPa, and the water-vapor transmission rate decreased from 319.8 +/- 38.7 to 288.9 +/- 23.5 g m(-2) day(-1). Therefore, SiO2, as a reinforcing agent in SA/P blends, represents a simple and effective strategy for improving the properties of biopolymer-based films in applications, such as packaging.

Automated summary

This study developed blend films based on sodium alginate and citrus pectin reinforced with different concentrations of SiO2. The results showed that the addition of SiO2 did not significantly modify the microstructure of the films or form new chemical bonds. However, there was a slight reduction in the crystallinities of the blends with the incorporation of SiO2. Among the formulations prepared, adding 5% SiO2 as a reinforcing agent resulted in improved mechanical and barrier properties.