Improving the Performance of Recycled Multilayer PET Through Reactive Compatibilization Strategies

The recycling of post-industrial multilayer polyethylene terephthalate (mPET) packaging waste remains a major challenge due to the coexistence of incompatible polymeric phases and the deterioration of properties during reprocessing. In this work, different reactive compatibilization strategies were evaluated to improve the processability and performance of recycled multilayer PET scraps generated during industrial packaging manufacturing processes. Several functional compatibilizers were investigated, including poly(ethylene-co-acrylic acid) (EAA), poly(ethylene-alt-maleic anhydride) (EMA), poly(ethylene-co-glycidyl methacrylate) (EGMA), poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMAGMA), and maleic anhydride (MA). The influence of compatibilization on the thermal, mechanical, chemical, surface, and morphological properties of recycled mPET was systematically analyzed. Processing behavior revealed that EMA- and MA-based formulations could not be successfully injection molded. In contrast, EAA-, EGMA-, and EMAGMA-based formulations showed suitable processability and enabled the production of defect-free specimens. Thermogravimetric analysis revealed only minor changes in thermal degradation behavior after compatibilization. In contrast, differential scanning calorimetry revealed changes in the melting behavior of the recycled formulations, while tensile and impact tests demonstrated marked improvements in ductility and toughness for EGMA- and EMAGMA-modified systems. Among them, EMAGMA provided the highest elongation at break and impact resistance. Contact angle measurements showed moderate changes in surface wettability, whereas density and hardness remained largely unaffected. FESEM analysis revealed a more homogeneous phase distribution and reduced dispersed-domain size in the compatibilized formulations, particularly for EGMA, indicating improved interfacial compatibility. These results demonstrate that glycidyl methacrylate-based compatibilizers are effective reactive agents for upgrading post-industrial multilayer PET waste into higher-performance recycled materials for different applications.