SbstractIn this work, the rheological, mechanical and morphological behavior of immiscible blend poly (methyl methacrylate) with elastomeric particles (PMMA elast ) and post-consumer poly (ethylene terephthalate) (PET) with and without the use of the interfacial compatibilizer poly (methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) (MGE) was studied. The significant increase in torque presented in rheological analyses has shown a indication of chemical reactions between the epoxy group of MGE with end groups of PET chains and also with the elastomeric phase of PMMA elast . The increased concentration of PET yielded an increase in maximum strength and elasticity modulus and a decrease in elongation at break. The PMMA elast /PET binary blend (50/50 wt%) and PMMA elast /PET/MGE compatibilized blend (65/30/5 wt%) showed pronounced results in elongation at break compared to PMMA elast , whereas, in the first results were due to the evidence of a co-continuous morphological structure and in the second, due to the efficiency of the dual reactive interfacial compatibilization of PMMA elast /PET blends. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed that PMMA elast /PET/MGE blends exhibit complex phase morphology due to the presence of elastomeric particles in the PMMA elast copolymer and in the use of MGE terpolymer.