Dynamically Cured PP/Epoxy Blends Compatibilised with MAH-g-PP

Abstract

The dynamic vulcanization process usually used to prepare thermoplastic elastomers was used to prepare polypropylene (PP)/epoxy blends compatibilised with maleic anhydride-grafted PP. The influence of dynamic cure, MAH-g-PP content, curing agents and epoxy equivalent weight on the mechanical properties of the PP/MAH-g-PP/epoxy blends was investigated. The torque at equilibrium of the blends increased with increasing epoxy resin content. The blends had better mechanical properties than either uncured PP/epoxy or dynamically cured PP/epoxy blends. The flexural modulus and impact strength increased rapidly with increasing MAH-g-PP content and reached a maximum of 2030 MPa and 36 J/m, respectively, at an MAH-g-PP content of 10 wt%. Those blends made using 2-ethylene-4-methane-imidazole as the curing agent had higher impact strength and flexural modulus than the ones made using dicyandiamide. The dynamically cured PP/MAH-g-PP/epoxy blends exhibited better mechanical properties at an epoxy equivalent of 2000 g/mol. The flexural modulus increased significantly with increasing epoxy resin content, while the elongation at break dramatically decreased, and the impact strength was only slightly affected by the presence of the epoxy resin. The PP/epoxy blends compatibilised with MAH-g-PP had finer domains than those of PP/epoxy blends. The FTIR spectra show that the functional groups of MAH-g-PP reacted with the epoxy resin. Dynamic mechanical thermal analysis (DMTA) results indicate that the compatibility between the PP and epoxy resin was improved by the addition of MAH-g-PP, and the storage modulus ( E') increased with increasing epoxy resin content. Thermogravimetric analysis (TGA) results show that the incorporation of epoxy resin into PP could improve the thermal stability of PP, and the dynamically cured PP/MAH-g-PP/epoxy blends had better thermal stability than the PP/epoxy and PP/MAH-g-PP/epoxy blends.