Investigating the Non-Linear Viscoelastic Behavior of Filled Rubber Compounds Through Fourier Transform Rheometry

2005 ◽  
Vol 78 (1) ◽  
pp. 54-75 ◽  
Author(s):  
Jean L. Leblanc
Keyword(s):  
Fourier Transform ◽  
Volume Fraction ◽  
Viscoelastic Behavior ◽  
Viscoelastic Response ◽  
Constant Frequency ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Non Linear ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic

Abstract Fourier transform (FT) rheometry was used to investigate the non-linear viscoelastic behavior of a series of carbon black filled rubber compounds with various filler levels. Using a purposely modified commercial dynamic rheometer, i.e. the Rubber Process Analyzer RPA 2000® (Alpha Technologies), special strain sweep tests protocols were designed and performed in order to capture the actual strain and torque signals up to 500% deformation at constant frequency and temperature. FT yielded the main component and harmonics of strain and torque signals. Results show that the quality of the applied strain signal somewhat deteriorates with increasing stiffness of filled compounds, but remains excellent in the high strain region, where the non-linear viscoelastic response of the materials is investigated. Above a filler volume fraction of around 12–13%, tested materials no longer exhibit a linear viscoelastic response, at least in the strain window investigated, and the FT rheometry results are more complex than what was observed with pure gum samples. This means that most practical rubber compounds are intrinsically non-linear. By essence, FT rheometry is a valid technique for both the linear and the non-linear domains and, as shown, provides original information about complex polymer systems such as filled rubber compounds.

Updating a Torsional Dynamic Rheometer for Fourier Transform Rheometry on Rubber Materials

2003 ◽  
Vol 76 (2) ◽  
pp. 287-298 ◽  
Author(s):  
Jean L. Leblanc ◽  
Christophe de la Chapelle
Keyword(s):  
Fourier Transform ◽  
Strain Amplitude ◽  
Filler Content ◽  
Filled Rubber ◽  
Linear Behavior ◽  
Rubber Compounds ◽  
Non Linear ◽  
Linear Viscoelastic ◽  
Fourier Transform Spectrum ◽  
Fast Electronic

Abstract A torsional dynamic rheometer has been suitably modified in order to collect actual torque and strain data, in view of studying the non-linear viscoelastic region. Essentially a fast electronic analogic - digital conversion card is used to record and treat torque and strain signals using a purposely written software. A Fast Fourier Transform (FFT) algorithm was first used in order to resolve recorded signals in harmonic peak components. Preliminary investigations were conducted with pure elastomers and filled rubber compounds in order to asses the testing capabilities of the system. As expected, when the non-linear viscoelastic response of a pure, unfilled rubber is produced through increasing strain amplitude, a number of significant odd-harmonic peaks appear in the Fourier Transform Spectrum (FTS). When testing intrinsically non-linear materials such as carbon-black filled rubber compounds, FFT gives also significant odd-harmonics whose relative intensities growth with filler content. Fourier transform rheology has therefore the capability to truly investigate non-linear viscoelasticity but cannot at first sight distinguish between the non-linear behavior appearing upon increasing strain amplitude (extrinsic non-linearity) and the non-linear behavior that reflects the complex heterogeneity of the material (intrinsic non-linearity). Other data analysis techniques were thus investigated; for instance, the detail examination of the actual shape of half-period torque signals. It appears that torque signal distortions are different providing they are obtained either through larger strain amplitude tests on pure polymer or by increasing filler content.

Viscoelastic Behavior of Carbon Nanotube Yarns and Twisted Coils

2018 ◽  
Author(s):  
Pouria Khanbolouki ◽  
Mehran Tehrani
Keyword(s):  
Carbon Nanotube ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Energy Harvesters ◽  
Linear Behavior ◽  
Non Linear ◽  
Stretchable Conductors ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Development And Validation

Coiled structures made from polymer and Carbon Nanotube (CNT) yarns are used as artificial muscles, stretchable conductors, and energy harvesters. The purpose of this work is to present our latest understanding of the mechanical behavior of these CNT-based structures. CNT yarns are fabricated by inserting twists in sheets spun from CNT forests. Over twisting the CNT yarns results in coiled CNT yarns, similar to a spring where the spring radius is comparable to the diameter of the CNT yarn. In this study, we explain the development and validation of a viscoelastic model, to capture damping and hysteresis in CNT yarns under quasi-static and dynamic loads. Confirmation of linear viscoelastic behavior of CNT yarns can lead us to the development of a model for coiled CNT yarns. Coiled CNT yarns, on the other hand, show a complex non-linear viscoelastic behavior. Possible mechanisms responsible for this non-linear behavior are discussed.

Non-linear viscoelastic behavior of fumed silica suspensions

1999 ◽  
Vol 38 (1) ◽  
pp. 14-25 ◽  
Author(s):  
F. Yziquel ◽  
P. J. Carreau ◽  
P. A. Tanguy
Keyword(s):  
Fumed Silica ◽  
Viscoelastic Behavior ◽  
Non Linear ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Silica Suspensions

Characterizing Gum Elastomers by Fourier Transform Rheometry

2003 ◽  
Vol 76 (4) ◽  
pp. 979-1000 ◽  
Author(s):  
Jean L. Leblanc ◽  
Christophe de la Chapelle
Keyword(s):  
Fourier Transform ◽  
High Strain ◽  
Dynamic Testing ◽  
Harmonic Component ◽  
Viscoelastic Behavior ◽  
Strain Range ◽  
Polymer Materials ◽  
Range Data ◽  
Non Linear ◽  
Linear Viscoelastic

Abstract Fourier transform (FT) rheometry is an emerging new technique that allows the linear and non-linear viscoelastic behavior of polymer materials to be accurately investigated. Basically samples are submitted to torsional harmonic strain at fixed frequency and temperature in order to capture strain and torque signals. A commercial instrument, i.e. the Rubber Process Analyzer RPA 2000® (Alpha Technologies), was suitably modified, essentially in using a fast electronic analogic-digital conversion card to record and treat torque and strain signals using purposely written software. Details of such modifications were previously published and the work presented is a sequel of this development. The quality of the applied strain is first precisely documented through FT and found excellent, particularly in the high strain range. Three gum EPDM with different macromolecular characteristics (MWD and long chain branching) were analyzed either using standard dynamic testing, i.e. essentially in the linear viscoelastic range, or using the Fourier transform rheometry approach, by considering data gathered in the far non-linear viscoelastic range. Data obtained are considered with respect to know features of the samples. A series of SBR 1500 samples, collected from various manufacturers, were first analyzed using standard methods; as expected very small differences were seen. Then FT was used to consider torque signals at very high strain (up to 400% at 1 Hz). Using a simple 4-parameter model to treat the variation upon increasing strain of the relative third harmonic component of the torque signal, differences are clearly detected that are discussed with respect to available polymer manufacturing information.

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