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.

The monohydroxy alcohol 5-methyl-3-heptanol is studied using rheology at ambient pressure and using dielectric spectroscopy at elevated pressures up to 1.03 GPa. Both experimental techniques reveal that the relaxational behavior of this liquid is intermediate between those that show a large Debye process, such as 2-ethyl-1-hexanol, or a small Debyelike feature, such as 4-methyl-3-heptanol, with which comparisons are made. Various phenomenological approaches assigning a time scale for the rheological signature of supramolecular dynamics in monohydroxy alcohols are discussed.

Nanocrystals composed mainly of β-sheet polyalanine are responsible for the high toughness of major ampullate (dragline) spider silk. Fourier-transform infrared (FTIR) spectroscopy is employed to study their response to (i) uniaxial stress and (ii) hydrostatic pressure. In the former a red shift and in the latter a blue shift of the vibration of polyalanine β-sheets at 965 cm −1 occurred. In both cases, a linear dependence is observed, which bends off for hydrostatic pressure greater than 1.4 GPa and is fully reversible up to 7 GPa. The seamless connection of negative and positive pressure regimes corroborate quantitatively our structural model of spider silk as composed of prestressed alanine-rich nanocrystals embedded in a glycine-rich amorphous matrix. It is also confirmed that nanocrystals withstand high pressures without undergoing structural transition or deteriorating their mechanical properties.

The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests.

Fourier-transform infrared (FTIR) spectroscopy is a common tool for determining, both qualitatively and quantitatively, the chemical composition of a material in the solid, liquid, or gas phase. It is additionally used as a technique to monitor the rate of chemical changes. These chemical changes can have rheological relevance, e.g., polymerization kinetics, rubber crosslinking, or epoxy curing, just to mention a few. We report the design of an IR transparent upper-plate rheological geometry used as an attenuated total reflectance (ATR) sampling tool. Additionally, we describe the technical and methodological adaption of the ATR crystal into an ARES G2 rheometer for combined FTIR and rheological measurements. In this new setup, a strain-controlled rheometer is combined with an ATR crystal and the IR beam is guided through two off-axis parabolic mirrors to the quasi-static upper plate of the rheometer to gain maximum IR sensitivity. Thereby online and directly correlated real-time FTIR spectra can be acquired while simultaneously conducting rheological measurements. This allows for in situ correlation of macroscopic rheological properties with microscopic and molecular chemical changes. These experiments are conducted for a material under controlled conditions having exactly the same sample time evolution for both measurements. To demonstrate its potential, this newly developed method was applied to correlate the polymer network formation for a free-radical copolymerization of acrylic acid and methylenebis(acrylamide) as a crosslinking agent via IR spectroscopy and the respective mechanical time evolution, in a dilute water-based solution.