The sound absorption coefficient is a commonly used parameter to characterize the acoustic properties of materials. The fire performance of construction products has to be evaluated on the basis of their reaction to fire performance. The evaluation of the reaction to fire performance for the flammable construction materials which are in Class E reaction to fire is based on the ignitability test and the thermal test using the radiant heat source. For this study, nine types of STERED® products, which were made from the recycled automotive technical textiles, were chosen in order to evaluate their ability for sound absorption and the reaction to fire. The fire performance was evaluated on the basis of the relative mass loss in the radiant heat source test; the ignitability in accordance with ISO 11925-2, the possible appearance of flame, duration of flame, and the glowing during the single flame source test. The sound absorption of nine products was rated on the basis of the sound absorption coefficient and the noise reduction coefficient. The measurement was performed using the transfer function method in accordance with ISO 10534-2. From the nine tested types of STERED® products, the product Senizol AT XX2 TL 60 had the lowest mass loss at thermal loads up to 700 °C and it fulfilled the conditions for Class E reaction to fire. This product had the highest noise reduction coefficient of 0.81 and a high absorption coefficient for frequencies ranging between 500 Hz and 2000 Hz. The STERED® product Senizol AT XX2 TL 60, as well as Senizol AT 22 TL 50, Senizol AT 40 TL 25, Senizol AT XX4 TL 50 and Senizol AT XX4 TL 10 with a sound absorption coefficient α of between 0.80 to 0.95 and corresponding NRCs from 0.66 to 0.81, these STERED® products can be classified according to ISO 11654 into the sound absorption classes A and B.

This article presents the results of an investigation of acoustic and thermophysical properties of insulation panels made from recycled technical textiles originating from the automotive industry. Measurements were performed on the samples of insulation panels (Senizol AT XX2 TL60), which were modified with liquid flame retardants (ISONEM® ANTI-FIRE SOLUTION, ECOGARD® B45, HR Prof). Another method of treatment was carried out by surface application of non-flammable facing (woven carbon fibre, nonwoven carbon fibre). Retardants were applied to the samples by surface spraying and soaking. The results showed a high ability of material to absorb sound in the frequency range 350 Hz–2 kHz. The sound absorption coefficient ranged from 0.82 to 0.9 in the frequency range 500 Hz–2 kHz. The noise reduction coefficient is 0.75. After material modification with the flame retardants, there was no significant change of sound absorption. The thermal conductivity coefficient of material before modification was 0.038 W⋅m−1⋅K−1. After application of the flame retardants, the thermal conductivity coefficient increased depending on type and method of retardant application in the range of 2.6–105.3%. The smallest change was detected after modification of material with ECOGARD® B45.