Dielectric anomalies in the β‐relaxation of glassy 1,4‐polybutadiene

Abstract

Abstract We have measured the dielectric relaxation of the polymeric glass‐former 1,4‐polybutadiene in the glassy and supercooled liquid state. The loss spectra ϵ″ of the β‐relaxation are measured between the lower detection limit at T = 125 K and T = 225 K > T β , with T β ≈ 210 K being the α‐β‐merging temperature. The related storage data ϵ′(ω) indicates that the β‐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 β‐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 β‐process in glasses. A tentative link between the β‐process and high frequency vibrational modes is established.