Passive underwater acoustic damping materials with Rho-C rubber–carbon fiber and molecular sieves

The effect of damping of underwater acoustic signals by composites with carbon fiber and molecular sieves of various pore sizes in Conathane EN-1556 based matrix is presented in this paper. The measurements were made in a water-filled pulse tube set-up for a frequency range of 4–12 kHz. The results show that molecular sieves of pore size 3 A are a better selection than others. Also, molecular sieves in the form of pellets gave good underwater acoustic damping and processability. With 11% mass loading of 3 A pellets in Conathane EN-1556 RhoC rubber containing 0.25% volume of carbon fiber, an echo reduction of 17–24 dB was obtained for a frequency range of 7–12 kHz.