By using MA modified EPDM rubbers with a similar high viscosity, it was possible to disperse 50 wt% rubber in the nylon matrix on account of reactive compatibilisation. In Fig. 2(b) a TEM micrograph is presented in which the rubber has an E/P ratio of 50/50 and a viscosity of 2395 Pa s. In this micrograph, the dark phase represents again the nylon phase. The principle of reactive compatibilisation is that the maleic anhydride groups of the modified rubber react in the melt with the amino-endgroups of PA6 leading to the formation of EPDM-g-PA6 graft copolymers. This graft copolymer will be preferentially situated between the nylon and the rubber phase. Hereby the interfacial tension between the phases is lowered and coalescence of the droplets is suppressed by steric hindrance [2], [15], [16], [17] and [18]. As a result, the phase inversion point is shifted and a very fine rubber dispersion is obtained. This binary nylon6/EPDM-g-MA blend with 50 wt% rubber shows excellent mechanical properties ( Table 2). Inside the rubber particles some nylon subinclusions can be observed ( Fig. 2(b)); these occlusions most probably arise from the steric stabilisation effect of the EPDM-g-PA6 which, if it encapsulates the nylon droplets, effectively prevents their coalescence with the nylon continuous phase.