Reinforcement of Thermo-Compressed Sodium Alginate Films with Calcium Alginate Powder

Alginate is a biocompatible and biodegradable polymer derived from seaweed. It has been extensively researched and developed for various applications. However, its poor mechanical properties present a significant drawback that limits its use in multiple fields. Furthermore, the fabrication of reinforced alginate films using conventional melt processing has the potential for scaling up production. This study aimed to enhance the mechanical properties of sodium alginate (SA) films by incorporating calcium alginate (CA) powder. The SA/CA biocomposite films were created using a thermo-compression technique, with glycerol acting as a plasticizer for the SA matrix. Various CA contents—2.5, 5, 10, and 20 wt%—were investigated. Scanning electron microscopy and energy dispersive spectroscopy revealed good interfacial adhesion between the SA film matrix and the CA powder. As the CA content increased, the moisture content of SA/CA biocomposite films decreased. The addition of CA powder significantly improved the tensile properties of the SA films. Based on the tensile test, SA/CA biocomposite films with 20 wt% CA powder exhibited a maximum tensile strength of 11.7 MPa and a Young’s modulus of 234.7 MPa. These results indicate a substantial increase of 208% in maximum tensile strength and 907% in Young’s modulus compared to SA films without CA. These findings indicated that the CA powder serves as an effective reinforcing filler for thermo-compressed SA films, which could lead to the development of high-strength alginate-based products for potential use in various applications, including biomedical, agricultural, and packaging applications.