ABSTRACT Recycling post‐consumer poly(ethylene terephthalate) (PET) using bio‐based feedstocks aligns well with sustainable development strategies. This work aims to efficiently recycle PET via glycolysis using fully bio‐based reactants, and to utilize the resulting recycled products for polyurethane–polyisocyanurate foam (PIR) applications. Here, bio‐based 1,2‐pentanediol, 1,5‐pentanediol, and castor oil (CO) were chosen as glycolysis agents for PET, yielding PET‐based polyol oligomers composed entirely of recyclable, bio‐based components. It was found that branched 1,2‐pentanediol yields glycolysis products with a lower melting point. Gel permeation chromatography (GPC) and 1 H NMR analyses confirmed that CO can participate in the one‐step glycolysis reaction. As the CO content in the glycolysis agent increased, the resulting glycolysates gradually transitioned from a paste‐like consistency to a room‐temperature liquid, while exhibiting a hydroxyl value of approximately 300–350 mg KOH/g. These glycolysates required no post‐treatment and could replace up to 100% wt% of conventional petrochemical polyol in PIR production. The resulting foams were characterized and compared with foams prepared from a commercially available phthalic anhydride‐based polyester polyol (PS‐3152). PIRs produced from the glycolysates exhibited good mechanical properties and superior thermal stability relative to PIR based on PS‐3152. In addition, glycolysate‐based PIRs showed a higher limiting oxygen index (LOI). Cone calorimetry indicated the flame retardancy of the prepared forms decreased as the CO content in the glycolysis agent increased.
Li et al. (Wed,) studied this question.