Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero‐shear viscosity

Ballauff, Matthias; Krämer, H.; Wolf, Bernhard

doi:10.1002/pol.1983.180210719

Cited by 8 publications

(3 citation statements)

References 26 publications

(5 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure3. comparison of the starting distribution of an anionically obtained polystyrene (B = 0) and the distributions after 6 h of shearing the presence of oxygen and in the presence of DPPH.…”

mentioning

confidence: 99%

Degradation of chain molecules. 2. Thermodynamically induced shear degradation of dissolved polystyrene

Ballauff¹,

Wolf²

1984

Macromolecules

Self Cite

View full text Add to dashboard Cite

The degradation of polystyrene (2.60 X 103 < P" < 1.50 X 104) in semiconcentrated solutions (4.9-20 wt %) in trans-decalm ( solvent) has been studied at moderate shear rates (laminar flow, 5 x 103 < < 104 s"1). The results demonstrate that the scission of the C-C bonds is induced by the poor solvent quality. The breakage of chains leads to radical fragments that either recombine or react with added radical scavengers. Special attention has to be paid to the choice of the radical scavengers in order to avoid changes in solvent quality. The rate of degradation increases strongly with concentration. The breakage probability evaluated on the basis of the method described in part l1 is Gaussian along the chain. The standard deviation, expressed by the parameter R, amounts in most of the cases to 1015% of the actual chain length. The exponent X describing the dependence of the rate of degradation on the individual chain length is comparatively small (0.1-0.9) and depends on temperature and shear rate. Since the effect is thermodynamically induced, the influence of temperature is very pronounced. All findings are compared to recent viscosimetric results2 and can be explained in terms of the modified Graessley theory.2,3

show abstract

mentioning

confidence: 99%

Degradation of chain molecules. 2. Thermodynamically induced shear degradation of dissolved polystyrene

Ballauff¹,

Wolf²

1984

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

“…We note that the majority of studies of nonlinear viscosity of polystyrene have been carried out under good solvent conditions. However Ballauff et al compare measurements of shear-rate dependent viscosity for 1.77 × 10 6 g mol -1 polystyrene in a ϑ solvent, trans -decalin, with a good solvent, toluene. , At high shear rates, the ϑ system exhibited some deviation from the constitutive behavior exhibited in Figure . This discrepancy they attributed to frictional effects associated with the attractive forces between chains which exist under ϑ solvent conditions.…”

Section: Resultsmentioning

confidence: 99%

NMR Investigations of Self-Diffusion and Shear Thinning for Semidilute Polymer Solutions near the Demixing Transition

Manz

Callaghan

1997

Macromolecules

View full text Add to dashboard Cite

Pulsed gradient spin echo and rheo-NMR methods are used to investigate semidilute solution properties of high molecular mass polystyrene in cyclohexane, in the vicinity of a demixing transition. The dependence of polymer self-diffusion on temperature and molar mass is measured using PGSE NMR. The molar mass variation is consistent with M -2 scaling while the temperature variation in approach to demixing can be modeled as a glass transition process using the WLF equation. The measured values of the demixing transition temperature Tp are consistent with known thermodynamic properties. By using NMR velocimetry, we are able to measure the velocity profiles for the polystyrene solutions when sheared in a cylindrical Couette cell. These profiles, which are consistent with strong shear thinning, are fitted using a power law fluid model, and entanglement renewal times obtained from the power law exponents are consistent with and complementary to tube disengagement times obtained from self-diffusion measurements, this family exhibiting M 3 scaling.

show abstract

“…The literature abounds with similar analyses [ 4, 10–19 ] using a large variety of polymeric materials. Few are directed at the accuracy of the predicted η 0 , although some compare various models.…”

Section: Introductionmentioning

confidence: 99%

On finding the zero‐shear‐rate viscosity of polymer melts

Shaw

2021

Polymer Engineering & Sci

View full text Add to dashboard Cite

A significant fraction of the experimental works on the rheology of polymer melts include an attempt to find the zero‐shear‐rate viscosity η0. This is done for good reasons, because η0 is a limiting property that depends only on thermodynamic variables and, importantly, the molecular and supermolecular structure of the melt. As with all limiting properties, η0 is impossible to measure directly. Fortunately with many melts, it can be estimated from viscosity measurements at very low shear rates or frequencies, but still remains one of those properties that becomes in the limit very prone to error. The common approach is to use a set of frequency‐ or shear‐rate‐dependent data and extrapolate to find η0. As with any extrapolation, the major question is the function used for the extrapolation. This question is addressed in some detail in this article. The question of which function to use was discarded in favor of using a large sample of 20 equations of many functional forms. This sample of randomly chosen equations was used to generate a set of η0 values, and the statistics of this distribution were examined, in the usual fashion, by description with an analytical probability density function that gives a high probability of being a likely generator of the data. In addition, a weighted average was proposed, where the weighting factor takes into account the quality of the fit. For testing these ideas, the room temperature melts of poly(vinyl isobutyl ether), poly(isobutylene), and poly(dimethyl siloxane) were used. The η0 of the latter was reachable; for the other resins, a falling ball technique was attempted.

show abstract

Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero‐shear viscosity

Cited by 8 publications

References 26 publications

Degradation of chain molecules. 2. Thermodynamically induced shear degradation of dissolved polystyrene

Degradation of chain molecules. 2. Thermodynamically induced shear degradation of dissolved polystyrene

NMR Investigations of Self-Diffusion and Shear Thinning for Semidilute Polymer Solutions near the Demixing Transition

On finding the zero‐shear‐rate viscosity of polymer melts

Contact Info

Product

Resources

About