2008/05/31 by Bo Jakobsen, Claudio Maggi, Tage Christensen +1 · 90 citations
Chemical Engineering · Materials Science · Physics and Astronomy · #Cole–Cole equation #Composite material #Condensed matter physics #Debye #Debye model #Dielectric #Fragility #Glass properties and applications #Glass transition #Material Dynamics and Properties #Materials science #Nuclear magnetic resonance #Physics #Relaxation (psychology) #Shear modulus #Thermodynamic properties of mixtures #Thermodynamics #cond-mat.soft
paper · pdf · doi:10.1063/1.3007988
published in The Journal of Chemical Physics 129(18), 184502 (American Institute of Physics) · 8 pages, 6 figures. Minor corrections, updated figures, more dielectric data shown
arxiv created 2008/10/03 · openalex publication_date 2008/11/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Shear-mechanical and dielectric measurements on the two monohydroxy (monoalcohol) molecular glass formers 2-ethyl-1-hexanol and 2-butanol close to the glass-transition temperature are presented. The shear-mechanical data are obtained using the piezoelectric shear-modulus gauge method covering frequencies from 1 mHz to 10 kHz. The shear-mechanical relaxation spectra show two processes, which follow the typical scenario of a structural (alpha) relaxation and an additional (Johari-Goldstein) beta relaxation. The dielectric relaxation spectra are dominated by a Debye-type peak with an additional non-Debye peak visible. This Debye-type relaxation is a common feature peculiar to monoalcohols. The time scale of the non-Debye dielectric relaxation process is shown to correspond to the mechanical structural (alpha) relaxation. Glass-transition temperatures and fragilities are reported based on the mechanical alpha relaxation and the dielectric Debye-type process, showing that the two glass-transition temperatures differ by approximately 10 K and that the fragility based on the Debye-type process is a factor of 2 smaller than the structural fragility. If a mechanical signature of the Debye-type relaxation exists in these liquids, its relaxation strength is at most 1% and 3% of the full relaxation strength of 2-butanol and 2-ethyl-1-hexanol, respectively. These findings support the notion that it is the non-Debye dielectric relaxation process that corresponds to the structural alpha relaxation in the liquid.