Insight into Chemical Recycling of Flexible Polyurethane Foams by Acidolysis.

Maja Grdadolnik,Petra Utroša,Ozgun Can Onder,David Pahovnik,Ana Drinčić,Ana Oreški,Ema Žagar

doi:10.1021/acssuschemeng.1c07911

Maja Grdadolnik, Petra Utroša + Show 5 more

Open Access

https://doi.org/10.1021/acssuschemeng.1c07911

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Abstract

Acidolysis is emerging as a promising method for recycling polyurethane foam (PUF) waste. Here, we present highly efficient acidolysis of PUFs with adipic acid (AA) by heating the reaction mixtures with microwaves. The influence of experimental conditions, such as reaction temperature, time, and amount of the degradation reagent, on the polyol functionality, molecular weight characteristics, the presence of side products, and the degree of degradation of the remaining PUF hard segments was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS), nuclear magnetic resonance (NMR), size-exclusion chromatography (SEC) coupled to a multidetection system, and Fourier transform infrared (FT-IR) spectroscopy. The purified recycled polyols were used for the synthesis of flexible PUFs. The morphology and mechanical properties of the PUFs show that the degree of functionalization of the polyol by the carboxylic end groups, which is higher for larger amounts of AA used to degrade the PUFs, significantly affects the quality and performance of the flexible PUFs from the recycled polyols.

Highlights

Polyurethane foams (PUFs) are used in a variety of comfort applications or as thermal and acoustic insulation materials
The reaction mixtures were heated by MW, and virgin polyol (VP) was used as a medium to facilitate stirring with a magnetic stirring bar and to prevent local overheating of the PUF
The reaction mixtures were heated with MW, which significantly reduced the reaction time compared to PUF acidolysis using conventional heating

Summary

■ INTRODUCTION

Polyurethane foams (PUFs) are used in a variety of comfort applications or as thermal and acoustic insulation materials. Chemical recycling of PUFs is carried out at high temperatures, mainly by conventional heating, there are some reports on microwave (MW)assisted degradation processes, especially in the case of glycolysis, where MW heating shortens the reaction time and improves the reaction yield.[17,19] Theoretically, all recycling technologies for polyether-based PUFs lead to hydroxylfunctionalized polyether polyol and oligourea hard segments end-capped with the applied degradation reagent.[14,17,19] the existing methods of chemical recycling of PUFs mainly suffer from incomplete and/or nonselective degradation of urethane linkages, as partial cleavage of urea groups in the hard segments occurs.

15 Recycled PUF5611

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES