EPDM rubber as an underwater acoustic window

Abstract

The ethylene-propylene-terpolymer (EPDM) class of elastomers has been widely suggested but rarely used in underwater acoustic devices. Recommendations for its use usually result from a recognition of its low acoustic losses and good match of sound speed and density with seawater. The hesitations about using EPDM's result from unknowns in its engineering properties of bondability and tear strength. The reported marginal bondability and tear strength were investigated as a function of EPDM formulation. Specifically, the effects of filler type and amount, sulfur or peroxide cure type and loading, and polymer parameters on both engineering and acoustic properties will be shown. With care in designing the EPDM formulation, this material can have acoustic properties (both rhoc and attenuation) as good as natural rubber and environmental resistance superior to neoprenes. EPDM's compatability with castor oil is the best of all common classes of elastomers. The results of many tests confirm that while EPDM's bondability and tear strength are not equal to neoprenes, they are nevertheless adequate for most applications.