We improved the recyclability of mixed poly(ethylene-terephthalate) (PET) and poly(lactic acid) (PLA) bottle waste. We made uncompatibilized and compatibilized PET/PLA blends of different weight ratios with a twin-screw extruder . Then, we analysed the mechanical properties, the miscibility and the thermal stability of the blends with and without compatibilizers . From the change in intrinsic viscosities (IV), we concluded that different reactions occur between the polymer chains due to the compatibilizers. We observed that when ethylene-butyl acrylate-glycidyl methacrylate (E-BA-GMA) as compatibilizer was added, the blends became tougher; elongation at break and Charpy impact strength increased, but Young's modulus of the blends decreased. In addition, the compatibilizers improved the thermal stability of the blends and this may have been caused by a number of mechanisms.