为提高聚丙烯（PP）增韧效率并研究其增韧机制，以PP/高密度聚乙烯（HDPE）共混物为基体，三元乙丙橡胶（EPDM）为增韧改性剂，通过熔融共混法制备PP/HDPE/EPDM共混物。结果表明：EPDM与HDPE形成核壳结构分散在基体中，并增强了与基体之间相互作用力。EPDM对PP的结晶具有促进作用，但对HDPE的结晶起到抑制作用，进而细化核壳结构分散相。随着EPDM含量的增加（4%~12%），PP/HDPE/EPDM共混物抗冲击强度增强，EPDM能够在增韧PP的同时延缓PP拉伸强度的快速下降。当EPDM含量为16%时，共混物的抗冲击强度达到11.18 kJ/m²，较PP/HDPE的抗冲击强度分别提高了158%。PP/HDPE/EPDM共混物的增韧机制为EPDM壳和HDPE核结构的空穴化作用，从而提升其能量的吸收。

In order to improve the toughening efficiency of polypropylene (PP) and study its toughening mechanism, PP/HDPE/EPDM blends were prepared by melt blending with PP/HDPE blends as matrix and ethylene propylene diene monomer (EPDM) as toughening modifier. The results show that the core-shell structure of EPDM and HDPE is dispersed in the matrix, and the interaction force between EPDM and matrix is enhanced. EPDM promotes the crystallization of PP, but inhibits the crystallization of HDPE, thereby refining the dispersed phase of the core-shell structure. With the increase of EPDM content (4%~12%), the impact strength of PP/HDPE/EPDM blends is enhanced, and EPDM can toughen PP while slowing down the rapid decline of PP tensile strength. When the EPDM content is up to 16%, the impact strength of the blend reaches 11.18 kJ/m², which is 158% higher than the PP/HDPE blends. The toughening mechanism of PP/HDPE/EPDM blend is the cavitation effect of EPDM shell and HDPE core structure, which enhances its energy absorption.