Relationship between global and segmental dynamics of poly(butylene oxide) studied by broadband dielectric spectroscopy

Osamu Urakawa; Minoru Yamane; Shota Tomie; Tadashi Inoue; Toshiyuki Shikata; Keiichiro Adachi

doi:10.1063/1.5006364

Relationship between global and segmental dynamics of poly(butylene oxide) studied by broadband dielectric spectroscopy

J Chem Phys. 2018 Jan 21;148(3):034904. doi: 10.1063/1.5006364.

Authors

Osamu Urakawa¹, Minoru Yamane¹, Shota Tomie¹, Tadashi Inoue¹, Toshiyuki Shikata¹, Keiichiro Adachi¹

Affiliation

¹ Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.

PMID: 29352792
DOI: 10.1063/1.5006364

Abstract

Relationship between segmental relaxation and normal-mode relaxation has been studied for molten poly(butylene oxide)s having various molecular weights by broadband dielectric spectroscopy over a wide temperature (T) range. We found that T dependence of the segmental relaxation time, τ_s, was weaker than the normal mode time, τ_n, at high T(>250 K ∼ T_g + 50 K), and the τ_n/τ_s ratio systematically decreased with increasing temperature. This high temperature complexity, whose mechanism has not been discussed in detail so far, was quantitatively explained by assuming the two step processes: local conformation change of polymers (elementary process) occurs first, and then the motion of a segment unit (second process) occurs. It was also found that the elementary process was strongly correlated with the experimentally observed β-relaxation.