Alkyd resins synthesized from postconsumer PET bottles

Simultaneous glycolysis and neutral hydrolysis of waste PET flakes obtained from grinding postconsumer bottles was carried out in the presence of xylene and an emulsifier at 180 °C. The product was separated from EG, water and xylene by filtration and was extracted by water at boiling point three times. The remaining solid was named water insoluble fraction (WIF). The filtrate was cooled to 4 °C and the crystallized solid obtained by filtration was named water-soluble crystallizable fraction (WSCF). These fractions were characterized by acid value (AV), hydroxyl value (HV) determinations. WSCF and WIF were used for preparation of the alkyd resins. Three long oil alkyd resins were prepared from phthalic anhydride (PA) (reference alkyd resin) or depolymerization product of the waste PET (PET-based alkyd resin), glycerin (G), sunflower oil fatty acids (SOFA) and glycol (EG) (reference alkyd resin) or depolymerization product of the waste PET (PET-based alkyd resin). Film properties and thermal degradation stabilities of these alkyd resins were investigated. Physical properties (drying times, hardness and abrasion resistance) and thermal degradation stabilities of the PET-based alkyd resins are better than these properties of the reference alkyd resin.