Toward Producing Supertough PET: Synergistic Action of Bio‐LDPE and LDPE‐g‐MA in Reactive Processing

ABSTRACT New blends of poly(ethylene terephthalate) (PET) and bio‐based low‐density polyethylene (Bio‐LDPE) were developed and compatibilized with low‐density polyethylene grafted with maleic anhydride (LDPE‐g‐MA) in ratios of 70/30 and 50/50 wt%, with compatibilizer contents of 5, 7.5, and 10 phr (parts per hundred of resin). The blends were processed via twin‐screw extrusion followed by injection molding. Comprehensive characterization was performed, including rheological, chemical, mechanical, thermomechanical, thermal analyses, and morphological evaluation. The compatibilized blends exhibited a reduced melt flow index (MFI) and higher torque, indicating improved melt stability during processing. Impact tests revealed outstanding performance for the PET/Bio‐LDPE/LDPE‐g‐MA (50/50/10) blend, showing a remarkable 1970% increase in impact strength compared to the non‐compatibilized system. Scanning electron microscopy (SEM) analysis revealed enhanced phase dispersion and interfacial adhesion, with the formation of interfacial connections between the polymeric phases, confirming the compatibilizer's effectiveness in the PET/Bio‐LDPE/LDPE‐g‐MA blends and supporting the observed improvements in impact strength and elongation at break. While the elastic modulus, tensile strength, and hardness decreased relative to neat PET, elongation at break significantly increased, indicating improved ductility. The heat deflection temperature (HDT) exhibited a slight decrease compared to neat PET; however, this reduction was not significant. Differential scanning calorimetry (DSC) analysis revealed the influence of the compatibilizing agent on the crystallization of the PET fraction, associated with a reduction in crystallinity. These results demonstrate that the produced blends are promising in the polymer industry, such as the packaging sector.