Effects of EVA-g-MA and EVACO compatibilizers/tougheners on morphological and mechanical properties of PP/EVA/HNT blend polymer nanocomposites

A series of polypropylene (PP)/poly(ethylene-co-vinyl acetate) (EVA) blend nanocomposites was produced by utilizing different amounts of organophilic halloysite nanotube (Org-HNT) and EVA-based compatibilizers/tougheners. They were prepared by using either only EVA elastomer or using EVA with the compatibilizers which are maleic anhydride grafted EVA (EVA-g-MA) and poly(ethylene-vinyl acetate-carbon monoxide) (EVACO) as well as maleic anhydride grafted PP (PP-g-MA). The morphology-mechanical property relationship was investigated as a function of nature of the compatibilizer and the amount of aluminosilicate nanotube/compatibilizer. The composites prepared without using the EVA-based compatibilizers in all nanotube loading degrees (1%, 3%, 5%) exhibited nanotube aggregates as evidenced by scanning electron microscope analyses. On the other hand, EVA-g-MA and EVACO provided a good dispersion of HNTs at both PP-EVA interface and in the PP matrix. The use of compatibilizers together with 3% Org-HNT resulted in PP/EVA blend nanocomposites with higher tensile modulus and toughness when compared to PP/EVA blend. Particularly, EVACO compatibilizer having highly polar carbonyl group at its backbone provided the highest toughness and Young's modulus as well as impact resistance for the 3% Org-HNT loaded nanocomposite while retaining the yield strength as an indication of a good balance between stiffness/toughness.