Glycolysis of poly(ethylene terephthalate) wastes in xylene

✍ Scribed by G. Güçlü; A. Kas¸göz; S. Özbudak; S. Özgümüs¸; M. Orbay

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 174 KB
• Volume: 69
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980919)69:12<2311::aid-app2>3.0.co;2-b

✦ Synopsis

To reclaim the monomers or prepare intermediates suitable for other polymers zinc acetate catalayzed glycolysis of waste poly(ethylene terephthalate) (PET) was carried out with ethylene or propylene glycol, with PET/glycol molar ratios of 1 : 0.5-1 : 3, in xylene at 170-245ЊC. During the multiphase reaction, depolymerization products transferred to the xylene medium from the dispersed PET/glycol droplets, shifting the equilibrium to glycolysis. Best results were obtained from the ethylene glycol (EG) reaction at 220ЊC, which yielded 80 mol % bis-2-hydroxyethyl terephthalate monomer and 20 mol % dimer fractions in quite pure crystalline form. Other advantages of employment of xylene in glycolysis of PET were improvement of mixing at high PET/EG ratios and recycling possibility of excess glycol, which separates from the xylene phase at low temperatures.