Explanation of the difference in temperature and pressure dependences of the Debye relaxation and the structural α-relaxation near T of monohydroxy alcohols

Isomeric effects in structure formation and dielectric dynamics of different octanols

“…Furthermore, it was reported that ring-chain transformations take place on the timescale of the Debye relaxation, an observation interpreted to correspond to fluctuations of the Kirkwood factor 67 . These notions were recently corroborated and extended to include not only the temperature but also the pressure dependence of the Debye relaxation 68 or to emphasize that despite a lacking calorimetric signature, the Debye process, like the Rouse modes in polymers, is entropic in nature 24 . It should be emphasized that the observation of Debye relaxations is by no means restricted to monohydroxy alcohols but well-known also for water and other dielectric liquids featuring large relaxation strengths ∆ 69 .…”

Entropic Nature of the Debye Relaxation in Glass-Forming Monoalcohols

“…It appears that the distinct supramolecular structures formed by hydrogen bonds give rise to the different activation correlation between the Debye and α relaxations. Albeit recent studies have reported the correlations of the Debye and α relaxations, 20,45 the quantitative correlation between the Debye and α relaxations established in the present work allows us to make a detailed comparison with the Rouse 1.…”

“…It appears that the distinct supramolecular structures formed by hydrogen bonds give rise to the different activation correlation between the Debye and α relaxations. Albeit recent studies have reported the correlations of the Debye and α relaxations, , the quantitative correlation between the Debye and α relaxations established in the present work allows us to make a detailed comparison with the Rouse modes and α relaxations in polymers. Using the thermal activation data of polymers DPIB (polyisobutylene doped with 1 wt % p - tert -octylphenolic resin) and DCIIR (chlorinated butyl rubber doped with 1 wt % p - tert -octyl phenolic resin), the activation energies of the Rouse modes and α relaxation were calculated at the relaxation time 100 s. Interestingly, we found that the Debye relaxation and Rouse modes have extremely similar activation correlation with their corresponding α relaxations, revealing a new feature existing commonly for the two dynamics, in addition to the earlier observations of the weaker temperature dependence relative to their α relaxations and the exponential parameter of β = 1. , Rouse dynamics and the corresponding α relaxation have been reported to share the same friction factor, and the same conclusion was also recently suggested for the Debye and α relaxations in monoalcohols …”

Is a Dissociation Process Underlying the Molecular Origin of the Debye Process in Monohydroxy Alcohols?

“… Temperature dependences of structural, τ α , and Debye, τ D , relaxation times determined for both n BOH (a) and 2EHOH (b) plotted together with the literature data taken from refs ( 22 , 23 ). In addition, we also included temperature dependences of primitive relaxation times calculated from the coupling model, CM (open star symbols) multiplied by A D / A 0 factor (filled stars) as discussed in ref ( 34 ). The inset in (a) shows the τ( T ) dependence plotted as a function of T g / T .…”

“…In this context, it is worth noting that supramolecular clusters mimic the polymer behavior only in the close vicinity of the glass-transition temperature, where H bonds are strong, and associates are the most physically stable. One can mention that in ref ( 34 ), the authors have presented a test to verify whether the formed chains are stable and the structural process resembles the segmental relaxation of a polymer. For that purpose, they applied the coupling model (CM), where the calculated primitive relaxation times were multiplied by the factor A D / A 0 to superpose with the ones determined for the Debye process.…”