Multiblock Copolymers for Recycling Polyethylene-Poly(ethylene terephthalate) Mixed Waste

Area of Science:

• Materials Science
• Polymer Chemistry
• Environmental Science

Background:

• Plastic pollution is a major global environmental issue, driven by high production of disposable plastics like polyolefins and polyesters.
• Current recycling rates remain low (<9% in the U.S.) due to challenges in processing mixed plastic waste and multicomponent plastics.
• Melt reprocessing of immiscible plastics results in poor material properties, hindering effective recycling.

Purpose of the Study:

• To synthesize novel poly(ethylene terephthalate)-polyethylene multiblock copolymers (PET-PE MBCPs).
• To evaluate the utility of these PET-PE MBCPs as adhesive tie layers in multilayer films.
• To assess the effectiveness of PET-PE MBCPs as compatibilizer additives for recycled plastic blends.

Main Methods:

• Synthesis of poly(ethylene terephthalate)-polyethylene multiblock copolymers (PET-PE MBCPs).
• Evaluation of PET-PE MBCPs as adhesive tie layers between PET and polyethylene films.
• Melt reprocessing of PET/PE blends with PET-PE MBCP additives to simulate mixed plastic waste recycling.

Main Results:

• PET-PE MBCPs demonstrated effective adhesion between PET and PE films, comparable to commercial adhesives.
• Melt-processed PET/PE (80/20 wt %) blends with ~0.5 wt % PET-PE MBCP showed improved mechanical properties compared to neat PET.
• The synthesized copolymers functioned as both adhesive promoting layers and compatibilizers.

Conclusions:

• PET-PE MBCPs offer a promising solution for enhancing the recycling of PET/PE mixed waste streams.
• These copolymers can improve the properties of recycled mixed plastics, enabling their reuse.
• The development of PET-PE MBCPs could significantly boost the circular economy for prevalent plastic types.