Temperature dependence of the nonergodicity parameter in polybutadiene in the neighborhood of the glass transition

Abstract

Using neutron-spin-echo and time-of-flight spectroscopy we have investigated the precise temperature dependence of the elastic (nonergodic) fraction in the spectrum of density fluctuations of the glass-forming polymer polybutadiene. With increasing temperature we found a critical decrease of the normalized elastic intensity following closely the (${\mathit{T}}_{\mathit{c}}$-T${)}^{1/2}$ behavior predicted by the mode-coupling theory. The critical temperature was determined to be ${\mathit{T}}_{\mathit{c}}$=216±1 K, i.e., 35 K above ${\mathit{T}}_{\mathit{g}}$.