ARTICLE Compatibilizer/graphene/carboxylated acrylonitrile butadiene rubber (XNBR)/ethylenepropylenediene monomer (EPDM) nanocomposites: Morphology, compatibility, rheology and mechanical properties Mohammad Javad Azizli 1 | Masoud Mokhtary 1 | Hossein Ali Khonakdar 2,3 | Vahabodin Goodarzi 4 1 Department of Chemistry and Chemical Engineering, Rasht Branch, Islamic Azad University, Rasht, Iran 2 Iran Polymer and Petrochemical Institute, Tehran, Iran 3 Leibniz Institute of Polymer Research Dresden, Dresden, Germany 4 Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran Correspondence Masoud Mokhtary, Department of Chemistry and Chemical Engineering, Rasht Branch, Islamic Azad University, Rasht, Iran. Email: mmokhtary@iaurasht.ac.ir Abstract In this study, nanocomposites based on different blends of XNBR/EPDM with 0, 0.1, 0.3, 0.5, 0.7, and 1 phr graphene were prepared on a two-roll mill. The role of EPDM-grafted maleic anhydride compatibilizer (EPDM-g-MAH) and the effect of graphene on morphology, curing characteristics, and mechanical prop- erties were investigated. The curing behavior of the nanocomposites was studied using a rubber curing rheometer. Also, microstructure of the nanocomposites was observed by transmission electron microscopy and scanning electron microscopy. With increasing the graphene content in the composite, in addition to the torque, the curing time and scorch time were increased. Fracture surface morphological studies indicated that the presence of EPDM-g-MAH improved the graphene dispersion within the XNBR/EPDM matrix and a uniform disper- sion with a small amount of aggregation was observed. On the other hand, the presence of graphene in the matrix created a rough fracture surface. In addition, with adding EPDM-g-MAH compatibilizer and increasing the graphene, the dis- persed phase size of EPDM in the XNBR matrix became smaller and a uniform dispersion was obtained. Also, hardness, tensile strength, fatigue, modulus, and elongation-at-break of XNBR/EPDM nanocomposite showed a significant increase by the addition of compatibilizer and increasing the graphene content. 1 | INTRODUCTION Polymer blends are considered as an economical way to benefit from each of the individual polymers. By chang- ing the composition and type of polymer components, the properties of the new polymer blends can be met to satisfy set specific requirements. [1,2] By these interpreta- tions, simple polymer blends may not always have the desired performance, the blends of two incompatible polymers, especially with large undesirable enthalpy of blending, leads to unintended phase separation and two-phase morphology, narrow interphase region, chemi- cal interaction, and poor physical property. [3] So, the development of interfacial additives or suitable com- patibilizers has always been one of the major issues in polymer blends research to achieve advanced polymer properties. [4–6] In recent years, graphene nanocomposites have attracted widespread attention among researchers as well as in industry. Thus, in various studies, by adding very small amounts of graphene due to their large surface area to volume ratio, the rheological, mechanical, and thermal properties of the polymer have been improved. [5,7] Received: 18 December 2019 Revised: 1 March 2020 Accepted: 2 April 2020 DOI: 10.1002/app.49331 J Appl Polym Sci. 2020;app49331. wileyonlinelibrary.com/journal/app © 2020 Wiley Periodicals, Inc. 1 of 16 https://doi.org/10.1002/app.49331