Thermoplasticized starch modified by reactive blending with epoxidized soybean oil

•Thermoplastic starch (TPS) was modified in situ by reactive blending with epoxidized soybean oil.•The condensation reaction was supported by FTIR.•Enhancement in the stiffness and strength was observed.•The hydrophobicity of the TPS was increased upon the addition of ESO.

Thermoplastic starch (TPS) was modified in situ with epoxidized soybean oil (ESO) using melt reactive blending in an internal mixer, in order to improve the stiffness and the mechanical strength of the TPS. Evidence of the condensation reaction between the epoxide ring of ESO and the hydroxyl groups was supported by FTIR. The evolution of the properties of the modified TPS, in terms of mechanical properties, microstructure and water absorption, was investigated using tensile mechanical, dynamic mechanical analysis (DMA), X-ray diffraction (XRD) and water uptake. The addition of ESO results in a huge enhancement in both Young's modulus and tensile strength. The hydrophobicity of the TPS was also increased upon the addition of ESO.