Effectively toughening polypropylene with in situ formation of core-shell starch-based particles.

Impact modifier particles with the core-shell structure in the polypropylene (PP) matrix were successfully prepared in situ by melt blending PP, thermoplastic starch acetate (TPAS) and poly(ethylene octane) grafted with maleic anhydride (POE-MA). It was found that the core was formed by TPAS, while the shell was formed by POE-MA. This core-shell particle plays an important role in toughening PP. The notched impact strength of PP/TPAS/POE-MA blend was as high as 68.1 KJ/m2 with an anticipated cost effectiveness. The mechanism of formation of the core-shell starch-based particles could be ascribed to the reactive compatibilization between TPAS and POE-MA which could be confirmed by SEM, and which dramatically improved the mechanical properties of the composites. This provides a new idea for the toughening modification of nonpolar PP, which could widely extend the application of starch and lower the cost.