Nanocomposites based on natural rubber, organoclay and nano-calcium carbonate: Study on the structure, cure behavior, static and dynamic-mechanical properties

•OC/NR, nano-CaCO3/NR and OC/nano-CaCO3/NR samples were prepared and characterized.•The use of nano-CaCO3 improved dispersion of OC and increased NR chemical resistance.•By using 5 phr OC and 10 phr nano-CaCo3 tensile strength of NR was improved about 350%.•The optimized sample in spite of having high elasticity exhibited high loss modulus.•Theoretical study in agreement to tests revealed high improvement of NR properties.

In this work, natural rubber (NR) based nanocomposites, using different amounts (0, 5, 10 and 15 parts per hundred rubber, phr) of nano-calcium carbonate (nano-CaCO3) with and without organoclay (OC) are prepared by melt mixing process. The prepared samples are characterized, performing X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), dynamic-mechanical thermal analysis (DMTA), swelling resistance in chemicals and tensile test. The tensile test results show that by the simultaneous using of 5 phr OC and 10 phr nano-CaCo3 the tensile strength is improved about 350%. The other tests such as XRD, FE-SEM, DMTA and swelling resistance tests as well as the theoretical investigation and calculating some thermodynamic parameters such as filler activity, activation enthalpy and Gibbs free energy reveal a considerable improvement of properties for the NR with OC and nano-CaCO3 in comparison to corresponding nanocomposites containing either one. The optimized sample in spite of having high elasticity exhibits high loss modulus which is very important in rubber product application.