Improved hydrophobic and physicochemical properties of maleated rosin‐modified thermoplastic starch

Abstract Herein, maleated rosin (MR) and glycerol were combined with corn starch to produce thermoplastic starch (TPS) to enhance its mechanical and water resistance properties. Different MR‐modified TPS samples were investigated in terms of their mechanical properties, cross‐sectional morphology, molecular structure, dynamic mechanical properties, water wettability, and moisture absorption behavior. Results indicated that increasing the MR improved the tensile and bending strength but also reduced the elongation at break and impact strength. Among them, the modified TPS composed of 600 g starch, 120 g glycerol, and 80 g MR, with the sample name 80MR‐TPS, has a tensile strength of 7.30 MPa and a bending strength of 4.83 MPa, which are about 4 times and 5 times higher than the unmodified TPS, respectively. In addition, SEM, FTIR, WAXD, and DMTA confirmed that esterification crosslinking was responsible for these physicochemical changes in microstructure. Notably, hydrophobicity increased with increasing MR content; the water contact angle reached 91.8° for 80MR‐TPS, indicating significant hydrophobicity compared to unmodified TPS (26.8°). Therefore, modifying TPS with MR provides an effective approach for producing hydrophobic TPS‐based plastics suitable for various applications such as disposable tableware, agricultural mulching films, or biomedical areas. Highlights This research aims to improve the hydrophobic and physicochemical properties of thermoplastic starch. Maleated rosin can be esterified with starch to improve the hydrophobicity of modified thermoplastic starch. Maleated rosin can significantly improve the strength of modified thermoplastic starch.