Synthesis and characterization of BHETA based new polyurethanes

Abstract

Recycling of polyethylene terephthalate (PET) by aminolysis breeds environmental benefits. In this work Polyethylene terephthalate in the form of waste fibers were subjected to depolymerization through aminolysis using excess amount of ethanolamine in the presence of sodium acetate, as catalyst. Obtained product, bis (2-hydroxy ethylene) terephthalamide (BHETA) was in its pure form with sufficiently high yields. The purified product was characterized by FTIR, 1 HNMR and 13 CNMR spectroscopy as well as melting point determination. Since catalyst and raw materials have low price, synthesis of this material is economical and could be used as diol to synthesis of polyurethanes. In this search, polyurethanes have been synthesized based on BHETA, HDI and polyethylene glycol via prepolymer method. Termogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) were carried out to study thermal stability, thermal transitions, T m and T g of synthesized polyurethanes. Effect of BHETA content in the main chain of synthesized polyurethanes on thermal stability of polyurethanes, strength and stiffness has been evaluated. BHETA based polyurethanes show Young's modulus about 300 MPa and elongation at break as 130% due to its aromatic structure.

Chemical upcycling of poly(ethylene terephthalate) waste: Moving to a circular model

“…In this way, it would be possible to maintain the value and improve the sustainability of PET-based materials, even upcycling discarded waste to obtain new materials with advanced performance. 32 For this reason, new ways have continued to be developed to overcome these drawbacks in PET recycling.…”

“…Taking into account the latest studies mentioned above, 31 chemical recycling by solvolysis is presented as a viable solution to the current shortage in the production of raw materials, that reduces dependence on the petroleum. In this way, it would be possible to maintain the value and improve the sustainability of PET‐based materials, even upcycling discarded waste to obtain new materials with advanced performance 32 . For this reason, new ways have continued to be developed to overcome these drawbacks in PET recycling.…”

“…Shamsi's group 34 observed that BHETA‐polyurethanes showed better performance as adhesives with respect to commercial ones. Later, Aslzadeh et al 32 evaluated that the introduction of BHETA motifs in polyurethane coating formulations led to an increase in toughness and stiffness, due to the formation of hydrogen bonds through amide groups. Conversely, these authors found that the thermal stability of those polyurethanes decreased with increasing BHETA content within the hard segment.…”

Polipropilen Lif Türü, İçeriği ve Uzunluğunun Sert Poliüretan Kompozitlerin Mekanik Performansına Etkisi

“…Polyurethanes are unstable and their degradation temperatures vary depending on chemical composition of polyurethane. Decomposition usually begins with degradation of urethane bond (approximately 150-220˚C) and release of CO2 and isocyanate [28,29]. Maximum weight loss occurs after 400˚C, possibly representing polyol degradation [30].…”