Maleic anhydride (MAH) grafted onto ethylene vinyl acetate copolymer (EVA), mEVA (modified EVA) was blended with poly(ethylene glycol-co-cyclohexane-1,4-dimethanol terephthalate) (PETG) with various mEVA and EVA (unmodified) content in the internal mixer. The effect of reactive compatibilizer to decrease the dispersed particle diameter was observed. The brittle-ductile transition was found at about d(n): 0.37 mm and d(v): 0.55 mu m of particle diameter, a critical particle diameter, regardless of EVA content, and the blend was also toughened at above the critical particle diameter regardless of dispersed EVA content and compatibility. The toughening mechanism and the effect of the particle diameter on the impact strength of the blend were investigated by morphological observation, and it was found that the toughening of the PETG/EVA blend system resulted from the shear deformation, induced by cavitation of dispersed EVA particles. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2600-2606, 2013