Potential of ultrasonic irradiation in polyurethane degradation in deep eutectic solvents (DES)

This study explores the degradation of polyurethane (PU) using deep eutectic solvents (DES) combined with ultrasonic irradiation, aiming to develop sustainable recycling techniques for PU waste. DES, formed from choline chloride and urea, possesses environmentally friendly properties such as low toxicity and high solubility, making it suitable for chemical recycling. Degradation experiments were conducted at elevated temperatures (130?C-150?C), both with and without ultrasonic assistance. The technique of GPC is applied to determine the molecular weight of raw PU and degradation product. The structures of DES, PU, and its degradation products were analysed using FTIR and NMR. The results indicate that the application of ultrasound significantly enhances the degradation rate at approximately 5.20% from 58.51 ? 0.04 % to 63.71 ? 0.03% at constant temperature of 150?C. This improvement is attributed to cavitation-induced effects, which facilitate polymer chain breakdown. Molecular transformations were confirmed through the presence of NH? groups resulting from the break of PU structure to form o-toluidine as identified by NMR. Reaction pathway were established through structural analysis of both raw PU and its degradation products. These findings demonstrate the potential of ultrasonic-assisted DES in advancing chemical recycling strategies for PU, addressing environmental concerns related to persistent PU waste, and promoting sustainable waste management practices.