Morphological characteristics and properties of PLA/TPS blending systems under different flow fields

To enhance the mechanical performance of polylactic acid (PLA) while maintaining its sustainability advantages, thermoplastic starch (TPS) was incorporated to fabricate PLA/TPS biocomposites under shear and extensional flow fields. Owing to the intrinsic immiscibility and polarity mismatch between PLA and TPS, the system typically exhibits weak interfacial interaction and inefficient stress transfer. This study systematically investigates the effects of flow fields on morphology evolution, interfacial characteristics, crystallization behavior and mechanical properties of PLA/TPS blends, with emphasis on the reinforcement mechanisms of extensional flow. The results show that extensional flow significantly refines the dispersed TPS phase, leading to improved dispersion uniformity and enhanced interfacial interaction, which promotes more efficient stress transfer. In addition, extensional flow facilitates increased crystallinity of the PLA matrix. Mechanical testing reveals that although the yield strength slightly decreases, the elongation at break is markedly improved, resulting in enhanced ductility and overall toughness. These improvements are attributed to the synergistic effects of morphology refinement, strengthened interfacial interaction and flow-induced crystallization. This work provides valuable insights into flow-induced reinforcement mechanisms for designing high-performance sustainable biocomposites.