Ultrasonic spectrometry of polystyrene latex suspensions. Scattering and configurational elasticity of polymer chains

Between 0.1 and 2000 MHz, the ultrasonic attenuation spectrum has been meas ured for suspensions of polystyrene latex globules in water. Ionically stab ilized and sterically stabilized samples have been studied at particle diam eters between about 65 and 93 nm. The spectra exhibit uniform characteristi cs for both types of suspensions. In the upper part of the measuring range (nu > 30 MHz) the ultrasonic excess attenuation can be well represented by loss mechanisms associated with scattering, particularly those related to t he monopole, dipole, and quadrupole oscillations of the latex globules. Whe n compared to literature data at low frequencies, the values for the ultras onic attenuation coefficient and for a Lame constant of the latex globules, as derived from the high-frequency part of the measuring range, indicate r elaxation processes occurring in the material. These processes are reflecte d by the low-frequency part of the spectra and are attributed to rotational isomerization of small segments of polymer chains.