New Strategy for Upcycling Marine Plastic Waste Through the Development of a Diamine-Functionalized Poly(ethylene terephthalate) Compatibilizer

A compatibilizer for low-density polyethylene (LDPE)/poly(ethylene terephthalate) (PET) blends was developed. This compatibilizer consists of amine-functionalized PET, which is blended with maleated polyethylene to form a copolymer. The goal is to use this compatibilizer in the future for recycling plastic waste from the marine environment. Fourier-transform infrared spectroscopy confirmed the successful incorporation of amine groups into PET chains through the addition of p-phenylenediamine in a molten state. An increase in diamine content allowed for the visualization of three bands where PET reacted with the diamine. Differential scanning calorimetry suggested that the polyester chains were grafted onto the maleated polyethylene backbone, with crystallinity increasing up to 2.5% diamine content. Scanning electron microscopy (SEM) images showed that the LDPE/PET blend resulted in a continuous polyethylene matrix with a dispersed polyester phase. The blend compatibilized with modified maleated polyethylene, and functionalized PET exhibited an improved interface. Oscillatory rheology and dynamic mechanical analysis indicated that the developed compatibilizer positively impacted the mechanical properties of the compatibilized LDPE/PET blends. This new approach enables the creation of innovative strategies for enhancing the properties of pre-existing polyolefin/polyester recycled blends.