Hybrid Reinforcement of NR/EPDM Blends Using Graphene Oxide and Halloysite Nanotubes via Mechanical Blending

Abstract

To address the need for enhanced mechanical properties and swelling resistance in industrial applications, this study developed hybrid nanofillers combining graphene oxide (GO) with halloysite nanotubes (HNTs) for natural rubber/ethylene-propylene-diene rubber (NR/EPDM) blends. Through mechanical blending, these fillers exhibited synergistic effects by uniformly distributing within the matrix and forming strong interactions with the polymer. The NR/EPDM composites demonstrated significant improvements, with tensile strength, stress at 100% elongation, tear strength, and abrasion resistance increasing by 92%, 31%, 60%, and 22%, respectively, over the base compounds. However, elongation at break and rebound resilience decreased by 28% and 31%, respectively. The enhancement in properties up to 6 phr was attributed to improved dispersion, increased polymer-filler interactions, and enhanced crosslinking density. Beyond this filler content, the benefits declined due to filler agglomeration, which led to stress concentration points, increased stiffness, and reduced elasticity, thereby compromising mechanical performance. Field emission scanning electron microscopy (FESEM) confirmed uniform dispersion at lower filler loadings, while higher concentrations resulted in localized agglomerations and microcracks, reducing overall efficiency.