Guidelines for rheological characterization of polyamide melts (IUPAC Technical Report)

2009 ◽  
Vol 81 (2) ◽  
pp. 339-349 ◽  
Author(s):  
Dick J. Dijkstra
Keyword(s):  
Rheological Properties ◽  
Preparation Method ◽  
Polyamide 6 ◽  
Temperature History ◽  
Rheological Characterization ◽  
Rheological Measurements ◽  
Industrial Organizations ◽  
Technical Report ◽  
Commercial Polymers

Most producers of polyamide have their own characterization method to study the rheological properties of polyamide 6 (PA6). However, the measured rheological properties depend strongly on the sample preparation method, humidity regulation, and time-temperature history during the measurement and not least on the kind of rheometer being used. This investigation is the result of an IUPAC project initiated by the Subcommittee on Structure and Properties of Commercial Polymers. Members of several industrial organizations, universities, and institutes cooperated, with the aim of formulating a guideline to measure reproducible rheological properties of PA6. The results of the investigation show the changes in molecular weight during different kinds of rheological measurements due to hydrolysis and amidization reactions. A guideline is introduced which can be used to make comparable rheological measurements on PA6.

scholarly journals Viscosity and Rheological Properties of Graphene Nanopowders Nanofluids

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 979
Author(s):  
Abderrahim Bakak ◽  
Mohamed Lotfi ◽  
Rodolphe Heyd ◽  
Amine Ammar ◽  
Abdelaziz Koumina
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Dynamic Viscosity ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Extraction ◽  
Rheological Characterization ◽  
Shear Rates ◽  
Rheological Measurements

The dynamic viscosity and rheological properties of two different non-aqueous graphene nano-plates-based nanofluids are experimentally investigated in this paper, focusing on the effects of solid volume fraction and shear rate. For each nanofluid, four solid volume fractions have been considered ranging from 0.1% to 1%. The rheological characterization of the suspensions was performed at 20 ∘C, with shear rates ranging from 10−1s−1 to 103s−1, using a cone-plate rheometer. The Carreau–Yasuda model has been successfully applied to fit most of the rheological measurements. Although it is very common to observe an increase of the viscosity with the solid volume fraction, we still found here that the addition of nanoparticles produces lubrication effects in some cases. Such a result could be very helpful in the domain of heat extraction applications. The dependence of dynamic viscosity with graphene volume fraction was analyzed using the model of Vallejo et al.

Rheological Characterization of Body Lotions

2001 ◽  
Vol 11 (2) ◽  
pp. 83-88 ◽  
Author(s):  
Ming Long Yao ◽  
Jayesh C. Patel
Keyword(s):  
Thermal Stability ◽  
Temperature Sensitivity ◽  
Viscoelastic Properties ◽  
Rheological Characterization ◽  
Performance Properties ◽  
Rheological Measurements ◽  
End Use ◽  
And Storage

Abstract This study is attempted to demonstrate the application of rheological measurements in characterization of cosmetics products. As part of this study, several rheological tests were carried out on three common, commercially available body lotions to analyze their complex properties. The tests described in this study were simple and predictive in which the viscoelastic properties were successfully related with the end-use performance properties such as applicability, processing behavior, temperature sensitivity and storage and thermal stability.

scholarly journals A Dynamic Semi-Circular Bending Configuration for the Rheological Characterization of Asphalt Mixtures

2020 ◽  
Vol 9 (3) ◽  
pp. 150-164
Author(s):  
Marina Cauhape Casaux ◽  
Silvia Angelone ◽  
Fernando Martinez
Keyword(s):  
Rheological Properties ◽  
Phase Angle ◽  
Dynamic Modulus ◽  
Plane Surface ◽  
Poisson Ratio ◽  
Asphalt Mixtures ◽  
Rheological Characterization ◽  
State Of Stress ◽  
Dynamic Loading Conditions

Many experimental procedures have been proposed for the determination of the rheological properties of asphalt mixtures. Among them, the indirect tensile test (ITT) has gained a lot of attention because of its relative simplicity and advantages. However, a biaxial state of stress is developed into the sample and then, the Poisson ratio must be estimated or measured for the calculations of the dynamic modulus. Looking for a testing configuration with the same simplicity and advantages, this paper proposes the Semi-Circular Bending (SCB) geometry with dynamic loading conditions in order to characterize the rheological properties (dynamic modulus and phase angle) of asphalt mixtures. Samples compacted in the laboratory or cored from in-service pavements can be used. A uniaxial state of stress is developed in the lower plane surface of the sample doing negligible the influence of the Poisson ratio on the dynamic modulus calculations. A specific experimental configuration was adopted and a 2D-FEM model has been used for the development of an equation for the calculation of the dynamic modulus. Two different asphalt mixtures were tested at diverse testing temperatures and loading frequencies. The obtained results have been analyzed and compared with those acquired with the more conventional testing configuration in uniaxial compression. An excellent agreement has been found for either the dynamic modulus or the phase angle with both sets of results. It could be concluded that the SCB configuration has been validated as a simple and promising methodology for the characterization of the viscoelastic response of asphalt mixtures.

scholarly journals Rheological Characterization of the Influence of Pomegranate Peel Extract Addition and Concentration in Chitosan and Gelatin Coatings

2021 ◽  
Vol 2 (3) ◽  
pp. 648-660
Author(s):  
Mirella Romanelli Vicente Bertolo ◽  
Rafael Leme ◽  
Virginia da Conceição Amaro Martins ◽  
Ana Maria de Guzzi Plepis ◽  
Stanislau Bogusz Junior
Keyword(s):  
Rheological Properties ◽  
Angular Frequency ◽  
Cross Linking ◽  
Rheological Characterization ◽  
Pomegranate Peel ◽  
All Solutions ◽  
Polymeric Solutions ◽  
Pomegranate Peel Extract ◽  
Peel Extract

In this study, the effects of an agro-industrial residue with active properties, pomegranate peel extract (PPE), were evaluated on the rheological properties of potential coatings based on chitosan (C) and gelatin (G). For this, rheological properties of the polymeric solutions were investigated in relation to PPE concentration (2 or 4 mg PPE g−1 solution), and to its incorporation order into the system (in C or in CG mixture). All solutions were more viscous than elastic (G″ > G′), and the change in PPE concentration had a greater influence accentuating the viscous character of the samples in which PPE was added to the CG mixture (CGPPE2 and CGPPE4). PPE addition to the CG mixture increased the angular frequency at the moduli crossover, indicating the formation of a more resistant polymeric network. This tendency was also observed in flow results, in which PPE addition decreased the pseudoplastic behavior of the solutions, due to a greater cross-linking between the polymers and the phenolic compounds. In general, all the studied solutions showed viscosities suitable for the proposed application, and it was possible to state the importance of standardizing the addition order of the components during the preparation of a coating.

Evaluation and role of rheological properties in sludge management

1997 ◽  
Vol 36 (11) ◽  
pp. 1-8 ◽  
Author(s):  
Steven K. Dentel
Keyword(s):  
Rheological Properties ◽  
Initial Value ◽  
Rheological Characterization ◽  
Practical Applications ◽  
Treatment Processes ◽  
Technological Advances ◽  
Sludge Characterization ◽  
Empirical Perspective

Rheological characterization of sludges represents one of the few examples of fundamentally derivable properties that has also been successfully related to actual sludge treatment processes. In understanding the relevance and utility of sludge rheology for practical applications, an historical perspective is of some initial value, and this paper summarizes previous developments in the rheological characterization of sludges and other non-Newtonian slurries, both from a theoretical and empirical perspective. In both cases, attention is brought to subtleties that must be considered if uniform and consistent rheological descriptions are to be obtained. Causes of the complex and variable rheological properties observed in sludges are then considered, with attention brought to particular aspects of upstream processes where some influence on sludge viscosity might be exerted. Finally, some practical aspects of rheometry are described. Recent research suggests that a variety of methods for sludge characterization and process optimization can be based on rheological measurements. Examples are presented that utilize both complex and relatively simplified technologies for this purpose, and some predictions are attempted of the probable directions for future developments. Internationally, approaches have differed and, while this diverse and competitive environment favors technological advances, the paper concludes by pointing out the need for consistency in rheological methods where fundamentally based parameters or regulatory concerns may be involved.

Rheological characterization of yield stress gels formed via electrostatic heteroaggregation of metal oxide nanoparticles

Soft Matter ◽  
2017 ◽  
Vol 13 (38) ◽  
pp. 6743-6755 ◽  
Author(s):  
Javen S. Weston ◽  
Jeffrey H. Harwell ◽  
Brian P. Grady
Keyword(s):  
Metal Oxide ◽  
Rheological Properties ◽  
Yield Stress ◽  
Metal Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Rheological Characterization ◽  
Oppositely Charged

Yield stress gels are formed when oppositely charged fumed nanoparticle species are dispersed in water. The gels are stable against sedimentation, have tunable rheological properties, and exhibit very little thixotropy.

scholarly journals Influence of dietary fiber addition on some properties of yoghurt

2013 ◽  
Vol 24 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Cristina Damian
Keyword(s):  
Rheological Properties ◽  
Dietary Fiber ◽  
Newtonian Fluids ◽  
Dietary Fibers ◽  
Rheological Characterization ◽  
Rotational Viscometer ◽  
Cheap Method ◽  
Fiber Addition

AbstractThe objective of this work was to study the effect of different dietary fibers on rheological properties of yoghurts fortified with these fibers [1, 2, 3]. Commercial fibers from apple and inulin were used. The effect of addition of dietary fibers in yoghurt [4, 5] was investigated by a rotational viscometer, Brookfield viscometer (Brookfield Engineering Inc., Model RV-DV I Prime) with RV spindles. The Brookfield viscometer DV I Prime with disk spindles represents an easy and cheap method for rheological characterization of non-Newtonian fluids, in this case of yoghurt. Syneresis and pH did not show any difference, while only apple fiber yoghurt showed colour differences compared to control.

scholarly journals Milligram Size Rheology of Molten Polymers

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 28 ◽  
Author(s):  
Salvatore Costanzo ◽  
Rossana Pasquino ◽  
Jörg Läuger ◽  
Nino Grizzuti
Keyword(s):  
Good Accuracy ◽  
Rheological Characterization ◽  
Rheological Measurements ◽  
Start Up ◽  
Molten Polymers ◽  
Linear Viscoelastic ◽  
Linear And Nonlinear ◽  
Living Organisms ◽  
Nonlinear Regimes

During laboratory practice, it is often necessary to perform rheological measurements with small specimens, mainly due to the limited availability of the investigated systems. Such a restriction occurs, for example, because the laboratory synthesis of new materials is performed on small scales, or can concern biological samples that are notoriously difficult to be extracted from living organisms. A complete rheological characterization of a viscoelastic material involves both linear and nonlinear measurements. The latter are more challenging and generally require more mass, as flow instabilities often cause material losses during the experiments. In such situations, it is crucial to perform rheological tests carefully in order to avoid experimental artifacts caused by the use of small geometries. In this paper, we indicate the drawbacks of performing linear and nonlinear rheological measurements with very small amounts of samples, and by using a well-characterized linear polystyrene, we attempt to address the challenge of obtaining reliable measurements with sample masses of the order of a milligram, in both linear and nonlinear regimes. We demonstrate that, when suitable protocols and careful running conditions are chosen, linear viscoelastic mastercurves can be obtained with good accuracy and reproducibility, working with plates as small as 3 mm in diameter and sample thickness of less than 0.2 mm. This is equivalent to polymer masses of less than 2 mg. We show also that the nonlinear start-up shear fingerprint of polymer melts can be reliably obtained with samples as small as 10 mg.

Rheological Enhancement of Artificial Sputum Medium

2020 ◽  
Vol 30 (1) ◽  
pp. 27-38
Author(s):  
Mingyang Tan ◽  
Yating Mao ◽  
Travis W. Walker
Keyword(s):  
Mechanical Properties ◽  
Cystic Fibrosis ◽  
Rheological Properties ◽  
Hierarchical Structure ◽  
Particle Transport ◽  
Xanthan Gum ◽  
Rheological Characterization ◽  
Diffusive Behavior ◽  
Long Timescales

AbstractThis investigation proposes a synthetic biofluid, artificial sputum medium (ASM) and xanthan gum (XG), that mimics the mucus from a patient with cystic fibrosis, and investigates the rheological properties both macroscopically and microscopically. Macroscopic rheological characterization cannot address the heterogeneity or the behavior of particle transport inside the mucus. Microscopic rheology enables the characterization of the microenvironment by using microparticles as probes.The addition of XG to ASM provides a tunable parameter that enables the mechanical properties to be consistent with real mucus. Particles that were suspended in a media of ASM with XG displayed a subdiffusive behavior at short timescales with a diffusive exponent that decreases with an increase in concentration of XG. At long timescales, particles that were suspended in ASM+XG with a concentration of XG of 0.1% to 0.4% displayed diffusive behavior. While in more concentrated samples (0.5% and 1.0%), the particles were constrained inside local elastic “cages”. The microscopic moduli that were calculated showed consistently lower moduli than rotational rheometry. This discrepancy suggests that the solutions of XG have a hierarchical structure that better represents the weakly associated microstructure of mucus that is found in real sputum.

Sign in / Sign up

Export Citation Format

Share Document