Investigation of the underwater sound absorption and damping properties of polyurethane elastomer

In this work, the acoustic absorption performance of polyurethane (PU) elastomer consisted of different molecular masses of polypropylene glycol (PPG), and a PU composite sample was made by adding multi-wall carbon nanotubes (MWCNT) was studied. Using the acoustic pulse tube device and spectrum of dynamic mechanical thermal analysis, modulus, glass transition temperature (Tg), damping, and acoustic absorption properties of PU with different components were analyzed. The sound absorption results in the frequency range of 2–18 kHz showed that the PU_2 (PPG 2000, TDI) had good acoustic absorption properties. The average acoustic absorption coefficient of PU_2 was 0.8, and the maximum acoustic absorption coefficient was 0.95. The PU_3 (PPG 1000, TDI + 0.1 mass% MWCNT) had lower acoustic absorption properties than PU_2, while the sample had a lower acoustic reflection coefficient compared to the samples PU_1 (PPG 1000, TDI) and PU_3. The damping properties showed that, with an increase in polyether molecular mass and also with the addition of MWCNT, the maximum value of tan(δ) was increased, while the glass transition temperature Tg decreased and increased compared to PU_1, respectively. The PU samples' hardness showed that the increase in molecular mass increases the soft segment and decreases the hardness, while the PU_3 hardness is superior to PU_2.