Study of dynamically cured PP/MAH-g-EPDM/epoxy blends

Abstract

In this paper, a novel method concerning the simultaneous reinforcing and toughening of polypropylene (PP) is reported. An epoxy resin was dynamically cured in a PP/maleic anhydride-grafted ethylene-propylene diene elastomer (MAH-g-EPDM) matrix to prepare dynamically cured PP/MAH-g-EPDM/epoxy blends. The small size of epoxy particles in the PP/MAH-g-EPDM/epoxy blends indicates the compatibilizing effect of MAH-g-EPDM. The structure of the dynamically cured PP/MAH-g-EPDM/epoxy blends is such that the epoxy particles are embedded in MAH-g-EPDM. The stiffness and toughness of the blends are in a good balance. The cured epoxy particles increase the stiffness of the blends, and the improvement in the toughness can be attributed to the embedded structure in the blends. The tensile strength and flexural modulus of the blends increase with increasing epoxy resin content, and the impact strength reaches a maximum of 360 J/m at an epoxy resin content of 20 wt%. A shift of crystallization peaks to higher temperatures suggests that dispersed particles in the blends can act as effective nucleating agents, accelerating the crystallization of PP components in the blends. Thermal gravimetric analysis results show that the presence of MAH-g-EPDM in the blends could reduce the thermal stability of PP, but the presence of epoxy resin could improve the thermal stability of PP. The dynamically cured PP/MAH-g-EPDM/epoxy blends have better thermal stability compared to PP.