Development of a Structurally Rigid, Acoustically Transparent Plastic
Abstract
Some underwater acoustical applications require a window that is both acoustically transparent and structurally rigid. No previous material possesses those properties, the closest being Poly(4-methyl-pentene) (PMP) plastic, whose specific acoustic impedance is 17% higher than seawater. A series of partially fluorinated epoxies is described that have sound speeds near water, but densities that are more than 50% higher than water. When these fluoro-epoxies are compounded with glass microspheres to lower their densities, their sound speeds increase too much to permit a match to water. When they are compounded with a mixture of glass microspheres and phenolic plastic microspheres, they achieve both a sound speed and a density match to a water medium. A panel of such a composite had an insertion loss of less than 1 dB from 10 to 100 kHz at normal incidence. The composites have attractive engineering properties. The components are commercially available. Keywords: Acoustical windows; Piezoelectric materials; Reprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1990
- Accession Number
- ADA220762
Entities
People
- Corley M. Thompson
Organizations
- United States Naval Research Laboratory