Multiblock Copolymers for Compatibilizing and Recycling PET and PE Mixed Waste Streams*

Poly(ethylene terephthalate) (PET) and polyethylene (PE) are two of the most prevalent plastics worldwide and they constitute a major portion of plastic waste. Unfortunately, it is difficult to directly recycle most plastic items, especially packaging products like multi-layer films that are composed of several immiscible polymers (e.g. PE and PET), since melt reprocessing of multi-component systems yields immiscible blends with poor mechanical properties. Effective compatibilizers can enhance blend component interfacial adhesion and improve mechanical properties of the recycled blends. In this study, we successfully developed PET-PE multiblock copolymer (MBCP) compatibilizers, which can be used as both adhesive layers in-between PET/PE multilayer films and compatibilizers for recycling PET and PE mixed waste streams. We systematically investigated the role of molecular architecture on compatibilization effects and transport phenomena. Results from three different compatibilizers, PET-PE MBCPs with random and alternating block sequencing, and PE-PET-PE triblock copolymer, with comparable total molar mass will be discussed.