Elastomeric nanocomposites were prepared from carboxylated acrylonitrile butadiene rubber/chloroprene rubber (XNBR/CR), graphene and a glycidyl methacrylate (GMA)-grafted XNBR (XNBR-g-GMA) compatibilizer by using a two-roll mill. The effect of graphene and XNBR-g-GMA compatibilizer on curing characteristics, rheological and mechanical properties and morphology of the nanocomposites was investigated. The curing properties and the morphology of the nanocomposites were studied by rheometry, SEM and TEM, respectively. The results of rheometry showed that by adding the XNBR-g-GMA compatibilizer and increasing the graphene content, the scorch time and optimum curing time decreased, but the torque increased, while the curing time increased with increasing CR percentage in the blend. Also, the results of DMTA tests showed that by adding the XNBR-g-GMA compatibilizer, there was compatibility between CR and XNBR and the dispersion of graphene in the XNBR/CR matrix was improved. This phenomenon was confirmed by direct observation of exfoliated graphene nanosheets by TEM. Also, the addition of XNBR-g-GMA and the increase of graphene content in the XNBR/CR matrix caused the fracture surface of the samples to be roughened and the size of dispersed phase (CR) in the XNBR matrix becomes smaller. The results of mechanical properties showed that the addition of the XNBR-g-GMA and increasing the graphene content resulted in increased hardness, fatigue strength, tensile strength, modulus and elongation-at-break.
28 April 2023 in Journal of Polymers and the Environment
In this paper, a novel rubber nanocomposite containing phenyl-vinyl-methyl-polysiloxane (PVMQ) and ethylene propylene diene monomer (EPDM) was produced during a two-roll mill procedure for mechanical applications. For this purpose, ethylene propylene diene monomer-grafted-maleic anhydride compatibilizer (EPDM-g-MAC) and graphene oxide (GO) was used as a compatibilizer and reinforcements to make a uniform composite. To study mechanical and physical characterizations, dynamic mechanical thermal analysis (DMTA), rheology, morphology, and curing characterizations of nanocomposites were investigated, which showed that compatibilizer makes GO dispersion uniformly. An electrical resistivity test was performed to study the electrical conductivity of the nanocomposites. The results indicate that the samples with higher GO content had a response to the electrical current. The curing study indicates that, by increasing the GO nanoparticles in the presence of EPDM-g-MAC, the curing properties are enhanced as well as mechanical properties by improving the bonding among GO, compatibilizer, and matrix [tensile strength (54%), modulus (68%), elongation-at-break (67%), hardness (81%), and fatigue (51%)]. FE-SEM and TEM images demonstrated that, by increasing GO nanoparticles in the presence of compatibilizer, the mean diameter of EPDM decreased in the substrate, which consequently increased the mechanical properties. The changes in surface temperature were investigated with constant voltage (75 V), which indicates that by increasing GO nanoparticles and electrical conductivity, the surface temperature increased significantly. The results of practical experiments showed good agreement with the theoretical results.