Resources Recycling ISSN:2765-3439(Print) 2765-3447(Online) 자원리싸이클링

The demand for poly(1,4-cyclohexylenedimethylene terephthalate) (PCT), a polyester with enhanced thermal and mechanical properties owing to the ring structure, is growing, necessitating advancing recycling technologies. However, challenges including preventing of increasing molecular weight and viscosity in the diol removal and concentration process, arise post-depolymerization during the chemical recycling of PCT. This study presents an innovative method to prepare liquid dihydroxyl group-terminated oligomers directly from PCT depolymerization using the metal chelate ethylenediaminetetraacetic acid (EDTA). Initially, PCT was depolymerized using an excess diethylene glycol and a Zn²⁺ catalyst to form an intermediate. Subsequently, the chelating agent was added, and the residual glycol was distilled and recovered under reduced pressure. EDTA was used to block the activity of the catalyst during high-temperature distillation to afford maximum trimer chain length and low-viscosity liquid polyols. ¹H and ¹³C nuclear magnetic resonance, gel permeation chromatography, and a viscometer were used to confirm the structure, molecular weight distribution, and viscosity of the prepared polyol, respectively. The as-prepared polyols were used as soft segments with 4,4’-methylene-bis(phenyl isocyanate) and 1,4-butanediol during the manufacturing of thermoplastic polyurethanes. The resulting polyurethane was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and mechanical testing.