Study on under-water sound absorption properties of Eucommia ulmoides gum and its blends

Abstract

The sound absorption performances of Eucommia ulmoides (EU) gum and its blends with conventional damping rubber are studied systematically. Blending 20%, 40% EU gum into chlorobutadiene rubber (CR), their under-water sound absorption property at 3–20 kHz is better obviously than that of CR. Blending 10, 20, 30, and 40% EU gum into chlorinated isobutene-isoprene rubber (CIIR), their sound absorption properties at 3–20 kHz are also better obviously than those of CIIR, especially the SAC of EU gum/CIIR (20/80) at 3 kHz is equal to 76% which is a great increase at low frequency region. The results show that a critical blend ratio of EU gum exists which is equal to 50%, if EU gum >50%, their under-water sound absorption properties are very poor, if EU gum 50%, the size of crystal of EU gum in the blend is still large which can reflect the incident sound wave like pure EU gum, so its under-water sound property is very poor; if EU gum <50%, the crystal of EU gum in the blend could be broken into many microcrystals scattering in the rubber matrix, like island in the sea, which can reflect incident sound wave more times, so its under-water sound property increase greatly.