Effect of a Pre‐Treatment on the Mechanical and Acoustic Properties of Recycled Ground Tire Rubber/Polyurethane Foam Composites

The large number of end‐of‐life tires (ELT) released into the environment as solid waste poses a significant problem with severe consequences for both human health and the global economy. Incorporating ELT into polymer matrices is considered an effective way to manage such tire waste. This study investigates the acoustic absorption, thermal, and mechanical properties of a flexible polyurethane (PU) matrix filled with ground tire rubber (GTR) particles produced through mechanical recycling of tires. To improve compatibility with the PU matrix, GTR powder undergoes preliminary chemical treatment with the oxidizing agent potassium permanganate (KMnO 4 ). A series of PU/GTR composites with GTR content up to 20 wt% is prepared using the free‐rise foam process. The physical and acoustic properties of these composites are evaluated through thermogravimetric analysis (TGA), uniaxial mechanical testing under compression, and acoustic spectral measurements across a wide frequency range. Results show a significant improvement in the properties of the PU matrix due to the addition of pre‐treated GTR particles. Notably, a shift of the peak absorption to lower frequencies is observed, consistent with the quarter‐wavelength theory. Additionally, comparison studies are conducted with two other series of PU/GTR composites treated with NaOH or H 2 O 2 as alternative oxidation methods. The similarities and differences based on the type of treatment are discussed. Overall, the findings confirm that GTR treated with KMnO 4 is an effective additive for producing high‐performance flexible PU foams suitable for thermal insulation and acoustic applications.