DEPOLYMERISATION OF POST-CONSUMER PET BOTTLES WITH AMINOLYSIS IN THE PRESENCE OF ORGANOCATALYST

Polyethylene terephthalate (PET) is a saturated polyester synthesized by the esterification of a dibasic acid (terephthalic acid) and a diol (ethylene glycol) and is used for fibres, bottles, films, and other moulded products. PET is recycled by both physical and chemical routes. The physical route generally consists of remelting and forming new products with the help of suitable additives. PET can be chemically reprocessed by complete depolymerisation into oligomers, monomers, and other by-products. In this way, a wide range of terephthalamide monomers can be produced, which can serve as building blocks for high-performance materials with desired mechanical and thermal properties. In this study, different amines (ethylenediamine - EDA, 1,4-diaminobutane - DAB, 1,6-diaminohexane - DAH) were used to depolymerise post-consumer PET beverage bottles. The bottles were cut into pieces with an edge length of less than 2 cm. Aminolysis of PET was carried out in the presence of organocatalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)) and with an excess of amine (ethylenediamine, 1,4-diaminobutane, 1,6-diaminohexane; 1.5 and 3 eq.). After completion of the reaction the product was isolated, washed with organic solvents and dried. The products bearing amino functional groups were characterised by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC).