Glycolyzed products from PET waste and their application in synthesis of polyurethane dispersions

• Published in: Progress in organic coatings Vol. 74; no. 1; pp. 115 - 124
• Main Authors: Cakić, Suzana M., Ristić, Ivan S., M-Cincović, Milena, Nikolić, Nada Č., Ilić, Olivera Z., Stojiljković, Dragan T., B-Simendić, Jaroslava K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-05-2012
• Subjects: Coatings; Fourier transform infrared spectroscopy (FTIR); Glycolysis; PET waste; Polyurethane dispersions; Thermal stability; Glycolysis; Polyurethane dispersions; Fourier transform infrared spectroscopy (FTIR); PET waste; Coatings; Thermal stability
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2011.11.024

► Waste PET were depolymerized using different molar ratio PET/glycol as 1:2 and 1:10. ► Glycolyzed products from PET waste were used for synthesis of PUD. ► The glycol type and molar ratio PET/glycol influenced on performance of PUD.
Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis with different molar ratio of glycol, such as propylene glycol (PG), triethylene glycol (TEG) and poly(ethylene glycol) (PEG 400), in the presence of a zinc acetate catalyst. These glycolyzed products were characterized by hydroxyl value (HV) determinations. The obtained glycolyzed products were reacted with isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA), as potential ionic center for water dispersibility, and mixed with ethylene diamine (EDA) as extender chain to prepare polyurethane dispersions. The PET glycolyzed products and polyurethane formation were characterized using Fourier transform infrared spectroscopy (FTIR). The molecular masses distribution of oligoester polyol and polyurethane dispersions were determined by using gel permeation chromatography (GPC). The effect of different PET/glycol molar ratio, on the physico-mechanical properties, such as hardness, adhesion test and gloss of polyurethane films were investigated. Thermal properties were investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC).
It was observed that initial degradation temperatures were at about 200°C, with two-or three degradation steps. The influence of different molar ratio PET/glycol on DTG curves showed stages that were not noticeable in the appropriate weight loss curves.
Polyurethane dispersions which lower molar ratio of PET/glycol in glycolyzed products showed lower thermal stability due to the presence of a greater amount of aromaticity in polyester backbone led to materials with higher film hardness. The values for the film adherence and gloss were confirmed their excellent properties for potential application for coatings in civil engineering, metal or polymer industry.