Optimizing silylated starch bioplastics with acrylated epoxidized soybean oils: influence of alkaline gelatinization...

This study examined the effects of alkali gelatinization and condensation/washing sequences on the structural and functional properties of silylated starch-based bioplastics incorporating acrylated epoxidized soybean oils (AESO). Silylated starch modified by 0-4 wt% NaOH exhibited stronger interactions with AESO than native starch, leading to enhanced thermal stability and reduced opacity of the bioplastics. 8-16 wt% NaOH significantly enhanced the degree of silane substitution through starch gelatinization but reduced the thermal stability of both starch and bioplastics. Notably, 16 wt% NaOH significantly decreased the water resistance of starch and bioplastics due to the degradation of starch. As a plasticizer, AESO improved the flexibility of the modified bioplastics, with 8 wt% NaOH-modified samples achieving the highest elongation at break (164.14 %). Silylated starch prepared using the condensation-washing process exhibited a higher degree of silane substitution than that obtained through the washing-condensation process, as early washing disrupted silane-starch interactions. Consequently, silylated starch prepared via the condensation-washing process demonstrated improved compatibility with AESO, enhancing the thermal stability, transparency, and water resistance of the bioplastics. The resulting bioplastics demonstrated good biodegradability. This study established a simple and effective silane modification strategy to enhance the compatibility of starch/AESO-based bioplastics, improving their flexibility, thermal stability, transparency, and biodegradability.