摘要
We performed thermal neutron spin echo measurements on a glass-forming polymer, deuterated polybutadiene (-[CD 2 -CD=CD-CD 2 ] n -; PB-d 6 ), in a high Q range up to 3.5 Å -1 covering the first and second peaks of the structure factor S(Q), and evaluated the decay rate Γ(Q) of the coherent intermediate scattering function as a function of Q. In contrast to the previous experimental findings on the first peak of S(Q) at Q = 1.5 Å -1 , no 'de Gennes' type narrowing was observed on the second peak at Q = 2.9 Å -1 . This novel finding indicates that the narrowing is hidden by the distinct motions of the soft -CD 2 -CD 2 - and =CD-CD 2 - units and the self-motions of the rigid and soft units in the Q range around the second peak. The temperature dependence of the relaxation rate Γ(Q) suggests that in the high Q range beyond the first peak of S(Q) the conformational changes in a deutrated PB chain are mainly observed. ©2005 The Physical Society of Japan.