title: Relaxation transition in glass-forming polybutadiene as revealed by nuclear resonance X-ray scattering.
abstract: We investigated the arrest mechanism of molecular motions in a glass forming polybutadiene near the glass transition using a new nuclear resonance synchrotron X-ray scattering technique to cover a wide time range (10(-9) to 10(-5) s) and a scattering vector Q range (9.6-40 nm(-1)), which have never been accessed by other methods. Owing to the wide time and Q ranges it was found for the first time that a transition of the α-process to the slow β-process (or the Johari-Goldstein process) was observed in a Q range higher than the first peak in the structure factor S(Q) at the critical temperature T(c) in the mode coupling theory. The results suggest the important roles of hopping motions below T(c), which was predicted by the recent extended mode coupling theory and the cooperative motions due to the strong correlation at the first peak in S(Q) in the arrest mechanism.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan.
authors.forename: Toshiji
authors.initials: T
authors.lastname: Kanaya
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan.
authors.forename: Rintaro
authors.initials: R
authors.lastname: Inoue
authors.affiliation: Elettra-Sincrotrone Trieste, S. S. 14 Km 163.5, I-34149 Trieste, Italy.
authors.forename: Makina
authors.initials: M
authors.lastname: Saito
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori, Osaka-fu 590-0494, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Seto
authors.affiliation: Japan Synchrotron Radiation Research Institute, Sayo, Hyogo-ken 679-5198, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yoda