Effects of multiwall carbon nanotube and perfluoroalkane additives on the sound absorption properties of flexible polyurethane foams

The sound absorption properties and airflow resistivity of polyurethane foams (PUFs) with multiwall carbon nanotube (MWCNT), perfluoroalkane (PFA), dimethylsiloxane (HMDS), and MWCNT/PFA hybrid additives were investigated with varying additive content. The results show the close relationship of the sound absorption coefficient and airflow resistivity, and increasing flow resistivity was found to improve the sound absorption coefficient of the PUF. For the PUF with MWCNT (at 0.50 phr)/PFA (at 1.25 phr) hybrid additives, the sound absorption coefficient and airflow resistivity were 0.80 (in the frequency range of 1,600–2,500 Hz) and 439,900 Ns/m⁴, respectively, which were the highest values among the investigated additive species and additive content. The sound absorption coefficient of the PUF with MWCNT (at 0.50 phr)/PFA (at 1.25 phr) was increased by 82.0% compared to that of the PUF without additives, probably because the PUF has the smallest cell size among the additive species and compositions investigated in this study. The results of the sound absorption coefficient, airflow resistivity, and cell size of the PUF suggest that to decrease the cell size and to increase the tortuous paths of the foams, MWCNT/PFA hybrid additives appeared to be the most effective additives and showed synergistic effects in the formation of PUF, and its small cell size increased the sound absorption properties of PUF. POLYM. COMPOS., 39:E1087–E1098, 2018.