Property of waste bottle‐grade polyethylene terephthalate restored by <scp>Ti</scp>‐based catalysts

Abstract This study employed titanium catalysts to degrade low‐quality PET (polyethylene terephthalate) bottle flakes and subsequently re‐polymerized the degradation solution to investigate whether the titanium catalyst could restore the physical and chemical properties of the degraded PET bottle flakes. The reaction process of property restoration was characterized using GPC, DSC, ICP, NMR, and so forth. The mechanism of titanium catalyst‐catalyzed PET polymerization was explored through simulation calculations. The results indicate that the waste PET bottle flakes have been restored to the standard of first‐grade PET bottle flakes under the degradation and re‐polymerization processes with the aid of dibutyl ethylene glycol titanate catalysts. The Ti ion in the recycled PET is stable and the metal ion leached from the restored PET in the strong acid environment meets food‐grade safety requirements. This study is expected to provide a new way for recycling waste PET bottle flakes.