Preparation of exfoliated and dispersed thermoplastic starch/montmorillonite nanocomposites via synergy of phase‐transition and ultrasonic in elongational flow field

Abstract In this study, a new mixing method and its principle via the synergy of phase‐transition and ultrasonic based on an elongational flow field were introduced in detail. Thermoplastic starch (TPS)/montmorillonite (MMT) nanocomposites from native corn starch were prepared using this novel method. The scanning electron microscope and x‐ray diffraction analyses confirmed that MMT can be efficiently exfoliated and dispersed evenly in the TPS matrix. Dynamic rheological analysis showed that exfoliated MMT obstructed starch molecular movement, increasing the viscosity and elasticity of TPS/MMT nanocomposites. Thermogravimetric analysis highlighted that evenly dispersed MMT enhanced the thermal stabilities of TPS/MMT nanocomposites. When the MMT content was 9 wt%, compared with nanocomposites prepared by melt blending alone, the tensile strength of TPS/MMT nanocomposites prepared by the new method increased from 5.8 to 14.3 MPa, and the oxygen permeability coefficient decreased from 13.43 × 10 −15 cm 3 ·cm/(cm 2 ·s·Pa) to 5.52 × 10 −15 cm 3 ·cm/(cm 2 ·s·Pa). This new method provided a promising pathway for the preparation of well‐exfoliated and evenly dispersed polymer‐based nanocomposites with excellent mechanical properties and barrier properties. Highlights A new mixing method based on the synergy of phase‐transition and ultrasonic in an extensional flow field for preparing exfoliated and dispersed TPS/MMT nanocomposites was proposed. The new method promoted the exfoliation and dispersion of MMT in the TPS matrix. The performance of TPS/MMT nanocomposites was significantly improved with the introduction of phase‐transition and ultrasonic.