Exploring the Potential to Repurpose Flexible Moulded Polyurethane Foams as Acoustic Insulators.

Enikő Mester,Béla Viskolcz,Béla Fiser,Kitti Gráczer,Ádám Filep,Dániel Pecsmány,Miklós Varga,Károly Jálics

doi:10.3390/polym14010163

Enikő Mester, Béla Viskolcz + Show 6 more

Open Access

https://doi.org/10.3390/polym14010163

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Abstract

Polyurethane flexible foams are widely used for a variety of applications to improve comfort and durability. Their long-term frequent use inevitably leads to the generation of waste that needs to be treated. The recycling and reuse of polyurethane waste are essential to achieve an environmentally friendly economy. The present study investigates the potential to reuse and repurpose flexible polyurethane foam from automotive seat cushion waste materials. Flexible foams were prepared with different hardnesses using isocyanate–polyol ratios between 0.8 and 1.2 NCO-index. Dry heat aging tests were performed to mimic the long-term usage of the materials. The decrease in compressive strength was compared with the change in acoustic damping properties before and after the aging tests using an acoustic tube, and the change in foam cell structures was also analyzed by micro-CT. On the basis of the results obtained, although the foam systems are no longer suitable to be used as seat cushions due to aging, they can still be used as sound insulation materials within a given frequency range, as their sound absorption capacity is suitable for such purpose.

Highlights

Flexible polyurethane (PU) foams are complex porous materials widely used in several comfort applications such as automotive seats and other types of cushioning [1]
Using micro-CT measurement, the change in foam cell structure was examined for all raw material ratios, and the results were found to be very similar for all hardnesses
A change of more than 10% in compressive strength was observed in all cases

Summary

Introduction

Flexible polyurethane (PU) foams are complex porous materials widely used in several comfort applications such as automotive seats and other types of cushioning [1]. The two main raw materials are isocyanate and polyol, which together form urethane bonds during polymerization, in addition to which suitable additives such as catalyst, blowing agent, and surfactant must be used to create a stable foam of adequate quality [3]. The polymeric phase can be considered as a block copolymer comprising a soft continuous matrix of polyether segments with dispersed hard segments consisting of urethane and urea groups [4]. The number of hard segments is based on the isocyanate ratio [5]. Hydrogen bonds in this segment are in part crystalline and act as physical crosslinks in the polymer [6]

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