From exfoliation to intercalation—changes in morphology of HNBR/organoclay nanocomposites

Hydrogenated nitrile rubber (HNBR)/organoclay nanocomposites (HNBR/OCNs) were prepared by mechanical mixing technique. By altering the temperature, pressure, and treatment time, respectively, the microstructural changes of HNBR/OCNs compounds under those treatments were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM) in detail. It was investigated that after the treatment, the exfoliated organoclay dispersion in untreated HNBR/organoclay compounds transformed into the co-existing of exfoliated, intercalated, and aggregated structures by de-intercalation action. Moreover, pressure, and temperature played accelerated roles in determining the final clay structures in HNBR/OCNs. It was suggested that the transformation was caused by the relaxation of HNBR chains, and it could be proceed spontaneously in thermodynamics under the treatment condition.