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Recycling of multilayer packaging using a reversible cross‐linking adhesive
Author(s) -
Kaiser Katharina M. A.
Publication year - 2020
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.49230
Subject(s) - materials science , adhesive , composite material , maleimide , thermoplastic , curing (chemistry) , polyethylene , polyurethane , polymer , food packaging , aluminium , chemical engineering , polymer chemistry , chemistry , layer (electronics) , engineering , food science
Plastic‐based multilayer packaging has an important function on the packaging market, but is currently not recyclable as the polymer layers used are usually thermodynamically immiscible. This work therefore follows the approach to prepare separable multilayer packaging using a packaging adhesive modified with thermally unstable adducts, and proposes a corresponding recycling process. For this purpose, typical multilayer structures (polyethylene (PE)// polyethylene terephtalate (PET), PET//aluminum, and PE//aluminum) were prepared by curing furan‐/maleimide‐functionalized polyurethane (PU)‐prepolymers with a three‐functional cross‐linking agent. Adhesions of up to over 3N per 15 mm test specimen were measured or substrate failures of PET films were observed. However, heating in dimethylsulfoxide, the retro‐Diels–Alder reaction takes place and the cross‐linked adhesive turns thermoplastic and dissolves in the solvent. Thus, the laminate separates and the pure PE, PET, and aluminum foils can be recovered without any PU residue.