title: Crossover of aging dynamics in polymer glass: from cumulative aging to noncumulative aging.
abstract: The aging behavior of polymer glass, poly(methyl methacrylate), has been investigated through the measurement of the ac-dielectric susceptibility at a fixed frequency after a temperature shift deltaT (< or = 20 K) between two temperatures T1 and T2. A crossover from cumulative aging to noncumulative aging could be observed with increasing deltaT using a twin-temperature (T-) shift measurement. Based on the growth law of a dynamical coherent length given by activated dynamics, we obtain a unique coherent length for positive and negative T shifts. The possibility of the existence of temperature chaos in polymer glasses is discussed.
authors.affiliation: Department of Polymer Science, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan. kfukao@se.ritsumei.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Fukao
authors.forename: S
authors.initials: S
authors.lastname: Yamawaki