Influence of Silane/Starch Ratios on Structure and Properties of Starch/Acrylated Epoxidized Soybean Oil‐Based Bioplastics

This study synthesized silylated starch by controlling the silane/starch molar ratios under alkali conditions and employed the resulting silylated starch along with acrylated epoxidized soybean oil (AESO) to prepare the bioplastics. As confirmed by FTIR and 1 H NMR analysis, 3‐aminopropyltriethoxy silane (APTES) was successfully linked to starch via the condensation reaction. Dropwise addition of NaOH solution facilitated the gelatinization of starch, resulting in a high degree of silane substitution of starch. The compatibility between silylated starch and AESO in the bioplastics was enhanced. On the other hand, NaOH led to the decomposition of starch, causing lower thermal and water resistance properties of starch and bioplastics. The increasing silane/starch molar ratios inhibited the starch gelatinization and decomposition by NaOH, resulting in the reduction of the degree of silane substitution of starch. However, bioplastics treated by higher silane/starch molar ratios exhibited higher thermal, mechanical, and water resistance properties, although there was poor compatibility between silylated starch and AESO. Additionally, the silane modification of starch reduced the opacity of the bioplastics remarkably, regardless of the silane/starch molar ratios. The silane treatment yielded a weak effect on the enzymatic degradability of the bioplastics. The resulting bioplastics are promising alternatives for packaging applications.