Improvement of acoustic properties of rigid polyurethane foam by adding textile waste can be observed from the
values of noise reduction coefficient (Fig. 7), which are higher in the case of composite materials. We can also
observe that with the increase of textile waste percentage, the value of noise reduction coefficient (NRC) also
increases. The 60-RPF material has the maximum NRC value of 0.593, which is twice as the 100% rigid
polyurethane foam.