화학공학소재연구정보센터
Langmuir, Vol.17, No.5, 1743-1751, 2001
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 measured for suspensions of polystyrene latex globules in water. Ionically stabilized and sterically stabilized samples have been studied at particle diameters between about 65 and 93 nm. The spectra exhibit uniform characteristics 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 the monopole, dipole, and quadrupole oscillations of the latex globules. When compared to literature data at low frequencies, the values for the ultrasonic attenuation coefficient and for a Lame constant of the latex globules, as derived from the high-frequency part of the measuring range, indicate relaxation processes occurring in the material. These processes are reflected by the low-frequency part of the spectra and are attributed to rotational isomerization of small segments of polymer chains.