Synthesis and physical-mechanical properties of polyurethane-polyisocyanurate foams based on PET-waste-derived modified polyols

A series of aromatic polyester polyols (APP) were synthesized by transesterification of industrial poly(ethylene terephthalate) (PET) waste using di(ethylene glycol) in the presence or absence of glycerol, adipic acid, poly(propylene glycol), or hexanediol as functional additives. PET-waste-derived modified APP was used for the synthesis of polyurethane-polyisocyanurate (PU-PIR) foams. The isocyanurate yield of the PU-PIR foams determined by the temperature method was high (67-90%) and correlated well with the data of Fourier transform infrared measurements. The effect of chemical structure of the APP and its properties (viscosity, acid number, and hydroxyl number) on technological characteristics of the PU-PIR foams at equal/similar formulations was studied. PU-PIR foams prepared using PET-waste-derived APP were characterized by high closed cell content (more than 94%). The presence of the fragments of glycerol in the structure of APP decreased the core density and tensile strength and increased elongation at break of the resulting PU-PIR foams while the presence of the fragments of adipic acid acted vice versa.