Investigation of effects of bis(2-hydroxyethyl) terephthalate derived from glycolysis of polyethylene terephthalate on the properties of flexible polyurethane foam

Abstract

This study investigated the potential of bis(2-hydroxyethyl) terephthalate (BHET), derived from the glycolysis of polyethylene terephthalate (PET) waste, as an additive in the synthesis of flexible polyurethane foam (FPUF), addressing the escalating environmental concerns associated with PET waste accumulation and the demand for sustainable material solutions. The influence of varying BHET content on the synthesis process, cellular architecture, and the intricate interplay between compositional variations and the resultant physical, mechanical, and thermal properties of FPUFs has been investigated. Our examination approach included analyses of foam density and cell morphology, comprehensive Fourier transform infrared (FTIR) spectroscopy for chemical structure elucidation, thermogravimetric analysis (TGA) to assess thermal stability, and differential scanning calorimetry (DSC) alongside mechanical property evaluations to discern the impact of BHET on foam performance metrics. Results emphasized the pivotal role of BHET in refining foam characteristics, where its inclusion facilitated the formation of foams with improvement in cell uniformity, subsequently affecting the foam’s apparent density. FTIR spectra analysis provided insight into the hydrogen bonding dynamics within polyurethane segments, revealing how BHET integration influenced microphase separation and the structural coherence of the material. The thermal and mechanical property assessments through TGA and mechanical testing demonstrated that the addition of BHET substantially augmented the thermal stability and mechanical performance of FPUFs.