LASER-LIGHT SCATTERING FROM MECHANICALLY EXCITED GELS

Laser inelastic light scattering was used to study gels which had been polymerized in light-scattering cuvettes. A sweep generator, connected to an audio frequency transducer, was used to excite mechanical oscillations in the samples. Discrete resonant peaks were noted in the voltage spectra of the scattered light at frequencies which are related to the dimensions of the cuvettes and the mechanical rigidity of the specimens. The temperature and concentration dependences of the shear modulus of elasticity were examined for several polyacrylamide gels. The data fit the relationship μ ~ Tcα, where the exponent α has the value α ~ 2.95. Complementary measurements also were made when the gels were not subjected to external mechanical excitation, and the temperature and concentration dependence of the resulting Lorentzian line widths were determined. © 1979, American Chemical Society. All rights reserved.