Experimental investigating on acoustic nonlinear parameters of epoxide compound during polymerization

Subject of the article is experimental investigating on nonlinear acoustic characteristics of media situated near percolation threshold associated with change of structure. Epoxide compound during polymerization is presented as a model. Time dependencies of sound velocity, wave attenuation, amplitudes of first, second and third harmonics are experimentally investigating simultaneously. Time dynamics of acoustic harmonics arouse particular interest and show dependence of “nonlinear acoustic portrait” of polymerization process from stage of polymerization, i.e. from structure of substance changing. Some typical aspects can be noted in harmonics behavior of acoustic field propagating into a medium with structural changing under the law of polymerization. Initial stage of polymerization shows amplitudes of first and second harmonics don’t change practically but amplitude of third harmonic increases noticeably. Second stage shows damping increases sharply and amplitudes of harmonics reduce considerably. Than damping becomes small and amplitudes of harmonics reach maximum values in a short time. Parameters of quadratic and cubic nonlinearity show extremum.