Dielectric anomalies in the beta-relaxation of glassy 1,4-polybutadiene

We have measured the dielectric relaxation of the polymeric glass-former 1,4-polybutadiene in the glassy and supercooled liquid state. The loss spectra epsilon ''(omega) of the beta-relaxation are measured between the lower detection limit at T = 125 K and T = 225 K > T-beta, with T-beta approximate to 210 K being the alpha-beta-merging temperature. The related storage data epsilon'(omega) indicates that the beta-process is a signature of supressing the higher frequency polarization with increasing temperature. rather than giving rise to additional polarizability at frequencies below the average relaxation frequency of the beta-process. This observation, as confirmed by data obtained for o-terphenyl and salol, contradicts the previous understandings of the mechanism underlying the Johari-Goldstein-type beta-process in glasses. A tentative link between the beta-process and high frequency vibrational modes is established.