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od 2020-09-20

Title: Local and global dynamics in the glass-forming di-isobutyl phthalate as studied by 1H NMR

Source: Solid State Nuclear Magnetic Resonance

Year : 1997

Abstract:

Spin-lattice relaxation times T-1 and T1ρ as well as H-1 NMR spectra have been employed to study the dynamics of the glass-forming di-isobutyl phthalate in the temperature range extending from 100 K, through the glass transition temperature Tg, up to 340 K. Below Tg NMR relaxation is governed by local dynamics and may be attributed to rotation of methyl groups at low temperatures and to motion of isobutyl groups in the intermediate temperature interval. Above Tg the main relaxation mechanism is provided by overall molecular motion. The observed relaxation behavior is explained by motional models assuming asymmetrical distributions of correlation times. The motional parameters obtained from Davidson-Cole distribution, which yields the best fit of the data at all temperatures are given.
(C) 1997 Elsevier Science B.V.

DOI: 10.1016/S0926-2040(96)01266-0   (Pobrane:  2020-10-23)