A scanning electron microscope (SEM) (JMS-5800 LV, JEOL) at an accelerating voltage of 6 kV was used to investigate the morphology of the cross-section of the MENR and MENR/CSt blends. The speci-mens were immersed in liquid nitrogen and their fractured surfaces were coated. Transmission Electron Microscopy (TEM) observations were performed with a JEOL JEM-2010. An ultra-thin section of the sample was obtained by ultramicrotomy at room tempera-ture using glass knives. The microtome used was a PowerTome PC(RMC). The sections were collected on TEM grids were stained withosmium tetroxide vapor for two hours. Osmium tetroxide react swith the carbon–carbon double bonds in the NR and this result inthe rubber network appearing darker.