ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

1aPA12. Sound absorption height and width limits for polymer glass transitions.

Bruce Hartmann

Gilbert F. Lee

John D. Lee

Jeffry J. Fedderly

Polymer Sci. Group, Naval Surface Warfare Ctr., 10901 New Hampshire Ave., Silver Spring, MD 20903

At the glass transition of a polymer, the shear sound absorption per wavelength displays a relaxation covering many decades of frequency. Calculations were made of the peak height and half-width of this relaxation based on the Havriliak--Negami dispersion relation. These calculations are an extension of our earlier study of the complex modulus loss factor height and width [B. Hartmann, G. F. Lee, and J. D. Lee, J. Acoust. Soc. Am. 95, 226--233 (1994)]. It was found that height and width are not independent: A high peak has a narrow width while broadband absorption can only be achieved for low-peak heights. The calculation predicts that height times width is approximately constant, as expected for a relaxation for which the area under the curve is constant. These predictions are compared with published experimental data on various polymers, chiefly polyurethanes, and found to be in good agreement.