Fig. 11 displays the tensile fracture surface of SBR/NBRr blends at a 50/50 blend ratio (a) and (c) with ENR-50; (b) and (d) are without ENR-50 at 300 magnifications and 5.00 magnification, respectively. It can be seen that, Fig.11(b, d) shows a coarser and poorer distribution of NBRr in the SBR matrix, particularly when more NBRr content was added to the SBR matrix. This shows low adhesion between phases and contributed to poor stress transfer across the interface. However, the surface of SBR/NBRr blends with ENR-50 [Fig. 11 (a and c)] illustrates better adhesion between NBRr and the SBR matrix. It can be seen that NBRr is still well bonded with the SBR matrix, which means strong interfacial adhesion occurred as compared to SBR/NBRr blends without ENR-50.