Study of the Sound Absorption Behavior and Cell walls Roughness of Flexible Polyurethane Foams

The relationship between sound absorption behavior and cell wall roughness of flexible polyurethane foams (FPUFs) was investigated in this article. FPUFs were prepared by methylene diphenyl diisocyanate (MDI), different synthesized linear aliphatic saturated polyesters, and the other ingredients. Water content and isocyanate index of all FPUFs were set to 5% and 110, respectively. Acoustic dampening behavior and cell wall roughness of FPUFs were investigated using an impedance tube device and atomic force microscopy ‎‎(AFM), respectively. Also, physical properties such as density and open cell content were measured. According to the results, by increasing the cell wall roughness, sound absorption efficiency increased up to 43.07%, maximum sound absorption coefficient (α) reached 0.98 and the area under the sound absorption curve was 3300 Hz due to the increase of the reflection, scattering, and absorption of sound waves. Finally, the results revealed that FPUFs with the roughness of 170-180 nm can be a ‎promising candidate for using as sound insulating materials in various environments.