Evaluation of physicochemical properties of citric acid crosslinked starch elastomers reinforced with silicon dioxide

Thermoplastic starch (TPS), derived from renewable resources, offers advantages such as biodegradability and lower production costs compared to petroleum-based plastics. However, its limited mechanical properties pose a challenge for broader applications. This research aims to explore the potential of enhancing the mechanical and barrier properties of TPS films through the incorporation of silicon dioxide as a reinforcement filler and citric acid as a crosslinking agent. By introducing silicon dioxide as a reinforcement filler, the mechanical strength of the TPS films is expected to be improved. Additionally, the incorporation of citric acid as a crosslinking agent is anticipated to enhance the barrier properties of the films. The combination of these additives holds promise for creating TPS films with improved performance, contributing to the development of sustainable and environmentally friendly materials in various industries. The results reveal that SiO₂ improves the stiffness of the films at lower concentrations but causes brittleness at higher concentrations. In contrast, citric acid crosslinked films exhibit improved flexibility and density. Scanning electron microscopy demonstrates the morphological changes in the films, with SiO₂ affecting surface roughness and aggregate formation. SiO₂ reduces film thickness and transparency, while citric acid enhances water resistance and barrier properties. X-ray diffraction analysis shows a reduction in crystallinity due to the plasticization process. Fourier-transform infrared spectroscopy highlights chemical changes and antimicrobial activity is observed with citric acid against specific bacteria. The soil burial test reveals that citric acid crosslinked films exhibit slower degradation due to antimicrobial properties. The combination of SiO₂ reinforcement and citric acid crosslinking enhances the overall performance of the films, promising sustainable and environmentally friendly materials for various applications.