The potential of natural rubber (NR) in controlling the morphology to promote selective localization of nano-filler in two-matrix epoxy/NR/GNP system was studied. The effect of NR contents (from 5 up to 30 vol%) on mechanical, thermal, and electrical performances of epoxy/NR and epoxy/NR/GNP systems were investigated. It was clearly observed that the mechanical properties of epoxy/NR/GNP system was higher as compared to epoxy/NR system, at 5 vol% of NR content. The incorporation of GNP nano-filler increased viscosity in the epoxy/NR/GNP system, thus, smaller NR phase has formed. The good interfacial adhesion between epoxy matrix and small NR phase promoted effective stress transfer, therefore, increasing the flexural strength, modulus, and toughness properties of the epoxy/NR/GNP system. Moreover, epoxy/NR/GNP system shows higher thermal stability as compared to the epoxy/NR system. Thermal decomposition temperature was delayed in the epoxy/NR/GNP system due to GNP nano-fillers have lower polymer chain mobility. It is interesting to note that electrical bulk conductivity of epoxy/NR/GNP system increases with increasing NR contents from 0 up to 30 vol%. XRD results has proven that NR phase acted as an effective elastomer spacer, which re-aligned the GNP nano-fillers to form more effective conductive pathways for more electrons to travel.
