화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.119, No.29, 8909-8916, 2015
Nonlinear Dielectric Behavior of a Secondary Relaxation: Glassy D-Sorbitol
We have studied the nonlinear dielectric behavior of a glass-forming liquid, d-sorbitol, with particular attention to its exceptionally intense JohariGoldstein (JG) type secondary relaxation. It is found that this beta-relaxation displays significant nonlinear dielectric effects, but these differ qualitatively from their alpha-process counterparts. High fields increase the amplitudes of the secondary modes (rather than reducing their time constants), consistent with a field induced increase of fictive temperatures. This result implies that the amplitudes of the secondary modes fluctuate in the glassy state, consistent with MD simulations reported for a liquid displaying a JG relaxation. The nonlinear features of this secondary process are reminiscent of those found for the excess wing regime, suggesting that these two contributions to dynamics have common origins.