Chemical recycling and repolymerization of poly(ethylene terephthalate), poly(ethylene furanoate), and their...

Replacing fossil-based plastics with bio-based ones is vital for future sustainability. However, bio-based plastics are not recycled within current recycling feeds, as polymers generally do not mix. Hence, mixing bio-based polymers with existing mechanical recycling feeds would yield materials of poor quality. For efficient recycling and as drop-in alternatives, bio-based polymers must have similar properties to the polymers in the feed they are mixed with. Chemical recycling and repolymerization can overcome incompatibility challenges by yielding copolymers. However, the question is: are the properties of the copolymers similar to those of the virgin homopolymers? Poly(ethylene furanoate) (PEF), a bio-based polymer, has similar properties to poly(ethylene terephthalate) (PET), such as high melting temperature, thermal stability, crystallinity, and gas-barrier properties. Both PEF and PET can be chemically recycled by solvolytic methods, and the obtained monomers can be repolymerized into copolymers that have similar properties to the virgin polymers. We have chemically recycled PET and PEF, repolymerized the recyclates into homo- and copolymers, and investigated the properties of the resulting polymers. We were able to repolymerize high-molecular weight polymers (M _w 63.5-123.4 kg mol^-1) with good mechanical properties (up to 43.2 MPa). Collecting PEF and PET waste in the same recycling feed and chemically recycling them make the utilization of bio-based plastic feasible on a global scale, while utilizing existing recycling streams.