Shear-Modulus Investigations of Monohydroxy Alcohols: Evidence for a Short-Chain-Polymer Rheological Response

Abstract

Liquids composed of small-molecule monohydroxy alcohols are demonstrated to display rheological behavior typical for oligomeric chains. This observation was made possible by rheological experiments in which more than seven decades in frequency and more than five decades on the mechanical modulus scale are covered. The singly hydrogen-bonded monohydroxy alcohols were chosen because they display significant, but surprisingly poorly understood effects of intermolecular association. Based on the present shear study, one can apply theoretical concepts of polymer science to understand the anomalous physical behavior of a wide range of hydrogen-bonded liquids.

Communication: Nonadditive dielectric susceptibility spectra of associating liquids

“…1(b). In harmony with the previous work, 22 the Debye process is rheologically identified as well since its dielectric feature matches the frequency at which the G ∝ ν 2 behavior sets in towards low ν.…”

“…The mixtures were prepared and measured analogous to the procedures described elsewhere. 21,22 For pure 2E1Br (x = 0), only a structural relaxation peak can be resolved that is accompanied by an essentially featureless low-frequency flank, see Fig. 1(a).…”

Communication: Slow supramolecular mode in amine and thiol derivatives of 2-ethyl-1-hexanol revealed by combined dielectric and shear-mechanical studies

“…49 A crossover from an intermediate to the terminal power law reported for shortchain polymers, polymeric liquids, or monoalcohols (ν 0.7 ) is an evidence of an additional slow supramolecular organization/dynamics. [23][24][25]42,50 In the present study, due to resolution limits of the PSG technique, we were not able to clearly observe the change of the frequency dependence of G ′ and G ′′ at modulus values lower than 1 MPa. However, the power law of the lowfrequency part of the mechanical loss shear spectra for amine (ν 0.85 ) and thiol (ν 0.93 ) shows that they display an intermediate behavior between the one reported for non-associating and associating liquids.…”

“…At the other extreme, we show 2-ethyl-1-hexanol with the relative viscosity increase by a factor of almost 10. 23 As can be seen, 48 The frequency dependent shear-modulus data for 2-ethyl-1-hexanol are taken from Ref. 23. amine and thiol show a slight enhancement of the viscosity at the low-frequency part.…”

“…[18][19][20][21] It was earlier believed that the Debye relaxation a) Electronic address: kadrjano@us.edu.pl was only seen in the dielectric signal but with improved experiments and data analysis it has over the last 10-15 years been detected also by other experimental techniques, such as mechanical spectroscopy, dynamic light scattering, and nuclear magnetic resonance. [22][23][24][25][26] The origin of the Debye relaxation in monohydroxy alcohols has been hotly discussed and intensively upgraded throughout the last century. 27 Today the consensus is that the process is due to slow dynamics in supramolecular hydrogen bonded structures.…”