A comparison of relaxation time distributions obtained from dynamic light scattering and dynamic mechanical measurements for high-molecular-weight polystyrene in entangled solutions

Abstract

The purpose of this work was to examine possible similarities between the relaxation time distributions for polystyrene in semidilute solutions in the solvent bis(2-ethylhexyl) phthalate (dioctyl phthalate, DOP) obtained from dynamic light scattering (DLS) and dynamic mechanical (DM) measurements. The paper deals mainly with the influence of concentration and molecular weight but also with the role of solvent quality through change in temperature. The DLS and DM relaxation functions have been analyzed by inverse Laplace transformation (ILT) and the DLS data also by fitting the slow, q-independent, part of the spectrum to a general exponential function. It was found that with both techniques the dynamical processes probed at long times are characterized by a similar wide range of relaxation times and that the latter increases strongly with concentration and molecular weight. However, the distribution of relaxation times from DLS is much more sensitive in the slow part of the spectrum to changes in solvent quality.

Microstructures and rheological dynamics of viscoelastic solutions in a catanionic surfactant system

“…Its characteristic time (hs s i) was found to be independent of the scattering factor q (Fig. 8), which is normally considered to arise from a structural relaxation of a three-dimensional network in the system [27][28][29][30]. Interestingly, the hs s i value (2.2 s) is well agreed with that of the mechanical relaxation time (t R = 2.1 s) obtained by the fit of dynamic rheology data to a Maxwell model.…”

Self-Diffusion and Cooperative Diffusion in Semidilute Polymer Solutions As Measured by Fluorescence Correlation Spectroscopy

“…[95][96][97][98][99][100][101][102][103] However, the microscopic understanding of the slow relaxation needs to be improved. 104 On the basis of our FCS and DLS measurements shown in Fig- The direct DLS measurement of the slow relaxation confirms our earlier remark that cooperative diffusion becomes highly correlated in the transient entanglement network and can be studied using only a small fraction of labeled polymer chains within FCS.…”

Effect of surface and bulk solution properties on the adsorption of whey protein onto steel surfaces at high temperature

“…Instead, it may indicate that the distribution of aggregates is very broad. The REPES analysis method can sometimes present artefactual peaks when the distributions are broad and other analysis has been employed (Nicolai, Brown, Hvidt, & Heller, 1990). Therefore, we choose not to further discuss the middle mode, but instead focus on the fast and the slowest mode.…”