A calibration technique to evaluate the power-law parameters of polymer melts using a torque-rheometer

1996 ◽  
Vol 36 (20) ◽  
pp. 2556-2563 ◽  
Author(s):  
Alfredo Marquez ◽  
Jafet Quijano ◽  
Marc Gaulin
Keyword(s):  
Power Law ◽  
Polymer Melts ◽  
Calibration Technique ◽  
Power Law Parameters

scholarly journals METHODS OF CFD MODELLING OF TWIN-SCREW PUMPS FOR NON-NEWTONIAN MATERIALS

2021 ◽  
Vol 2021 (6) ◽  
pp. 5366-5372
Author(s):  
MARIAN BOJKO ◽  
◽  
LUKAS HERTL ◽  
SYLVA DRABKOVA ◽  
◽  
...  
Keyword(s):  
Power Law ◽  
Food Industry ◽  
3D Model ◽  
Design Parameters ◽  
Cfd Modelling ◽  
Ansys Fluent ◽  
Screw Pump ◽  
Twin Screw ◽  
Definition Of ◽  
Power Law Parameters

The twin-screw pump is designed for pumping highly viscous materials in the food industry. Rheological characteristics of materials are important in the specification of design parameters of screw pumps. Analysis of flow in the twin-screw pumps with definition of non-newtonian materials can be made by numerical modelling. CFD generally oriented software ANSYS Fluent and ANSYS Polyflow has been used for modelling. In this study those software’s (ANSYS Fluent and ANSYS Polyflow) were defined for solution of flow in the twin-screw pumps. Results were compared for the same boundary conditions on the inlet and outlet of the 3D model. For definition of the viscosity were used the Nonnewtonian power law. Parameters as consistency coefficient and flow exponent for Nonnewtonian power law were analysed by software ANSYS Fluent and ANSYS Polyflow. Postprocessing form ANSYS Fluent and ANSYS Polyflow were made by contours of field and by graphs.

Correlation analysis of the power law parameters for viscosity of some engineering fluids

2017 ◽  
pp. 1-9 ◽  
Author(s):  
R.B. Haj-Kacem ◽  
J.V. Herráez ◽  
A.A. Al-Arfaj ◽  
M.A. Alkhaldi ◽  
N.O. Alzamil ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Power Law ◽  
Power Law Parameters

Influence of epoxidation conditions on the rheological properties of gel-like dispersions of epoxidized kraft lignin in castor oil

Holzforschung ◽  
2017 ◽  
Vol 71 (10) ◽  
pp. 777-784 ◽  
Author(s):  
Esperanza Cortés-Triviño ◽  
Concepción Valencia ◽  
José M. Franco
Keyword(s):  
Power Law ◽  
Castor Oil ◽  
Complex Modulus ◽  
Softening Temperature ◽  
Gel Strength ◽  
Rheological Characterization ◽  
Scanning Calorimetry ◽  
Small Amplitude Oscillatory Shear ◽  
Power Law Equation ◽  
Power Law Parameters

Abstract The modification of castor oil (CO) with lignin was the focus of this research to create a lubricating medium with improved gel-like properties. Namely, an alkali lignin (L) was epoxidized with epichlorohydrin (EP) and the resulting LEPs were dispersed in CO. The parameters of LEP synthesis were varied and the epoxidation index (EPI) of the LEPs was determined. The LEPs were also submitted to thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Rheological responses of the LEP/CO dispersions were investigated through small-amplitude oscillatory shear (SAOS) tests. Linear viscoelasticity functions are quantitatively affected by the epoxidation parameters, such as temperature, reaction time and L/EP and L/NaOH ratios. In general, lignins with higher EPI show higher values of the SAOS functions, which are indicative of better gel-strength due to a higher cross-linking density between the LEPs and CO. A power-law equation describes well the evolution of the complex modulus, G*, with frequency of gel-like dispersions, where the power-law parameters were found to increase almost linearly with the EPI. The thermo-rheological characterization provides a softening temperature beyond 50°C.

Evaluation of the Gradation Effect on the Dynamic Modulus

2005 ◽  
Vol 1929 (1) ◽  
pp. 193-199 ◽  
Author(s):  
Bjorn Birgisson ◽  
Reynaldo Roque
Keyword(s):  
Power Law ◽  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Design Procedure ◽  
Maximum Size ◽  
Pavement Design ◽  
Aggregate Gradation ◽  
Higher Temperature ◽  
Power Law Parameters ◽  
Selection Of

The importance of aggregate characteristics has been emphasized in the Superpave® asphalt mixture design procedure. However, criteria for guidelines for the selection of suitable aggregate gradations–-other than gradation limits for different nominal maximum size aggregate blends, including the restricted zone–-have been neglected. With the move toward mechanistic–empirical pavement design, the dynamic modulus is used to account for mixture properties in the pavement design. It is of significant importance to mix designers to possess a framework for determining how to optimize a mixture for ensuring an adequate dynamic modulus. This paper presents the results from a study of the effects of gradation characteristics on the dynamic modulus. Power law–based gradation factors are obtained for 13 aggregate gradations (coarse and fine graded) composed of limestone and granite aggregates. These gradation factors were used to identify and evaluate relationships between gradation factors and the dynamic modulus at higher temperature (40°C). Subsequently, a tentative framework was established for optimizing mixture gradations for dynamic modulus values. Findings illustrate that gradation factors based on power law parameters can be used to optimize mixture gradations for key mixture properties, such as the dynamic modulus. Results also demonstrate the critical nature of aggregate gradation in achieving desired mixture properties.

scholarly journals Elongational viscosity scaling of polymer melts with different chemical constituents

2021 ◽  
Vol 60 (4) ◽  
pp. 163-174
Author(s):  
Esmaeil Narimissa ◽  
Leslie Poh ◽  
Manfred H. Wagner
Keyword(s):  
Power Law ◽  
Molar Mass ◽  
Polymer Melts ◽  
Chemical Constituents ◽  
Elongational Flow ◽  
Weissenberg Number ◽  
Elongational Viscosity ◽  
Viscosity Data ◽  
Strain And Strain Rate ◽  
Linear Viscoelastic

AbstractMorelly et al. (Macromolecules 52:915-922, 2019) reported transient and steady-state elongational viscosity data of monodisperse linear polymer melts obtained by filament-stretching rheometry with locally controlled strain and strain rate and found different power law scaling of the elongational viscosities of polystyrene, poly(tert-butylstyrene) and poly(methyl-methacrylate). Very good agreement is achieved between data and predictions of the extended interchain pressure (EIP) model (Narimissa et al. J. Rheol. 64, 95-110 (2020)), based solely on linear viscoelastic characterization and the Rouse time τR of the melts. The analysis reveals that both the normalized elongational viscosity and the normalized elongational stress are dependent on the number of entanglements (Z) and the ratio of entanglement molar mass Mem to critical molar mass Mcm of the melts in the linear viscoelastic regime through $$ {\eta}_E^0/\left({G}_N{\tau}_R\right)\propto {\left({M}_{\mathrm{em}}/{M}_{\mathrm{cm}}\right)}^{2.4}{Z}^{1.4} $$ η E 0 / G N τ R ∝ M em / M cm 2.4 Z 1.4 and $$ {\sigma}_E^0/{G}_N\propto {\left({M}_{\mathrm{em}}/{M}_{\mathrm{cm}}\right)}^{2.4}{Z}^{1.4} Wi $$ σ E 0 / G N ∝ M em / M cm 2.4 Z 1.4 W i , while in the limit of fast elongational flow with high Weissenberg number $$ Wi={\tau}_R\dot{\varepsilon} $$ Wi = τ R ε ̇ , both viscosity and stress become independent of Z and Mem/Mcm, and approach a scaling which depends only on Wi, i.e. ηE/(GNτR) ∝ Wi−1/2 and σE/GN ∝ Wi1/2. When expressed by an effective power law, the broad transition from the linear viscoelastic to the high Wi regime leads to chemistry-dependent scaling at intermediate Wi depending on the number of entanglements and the ratio between entanglement molar mass and critical molar mass.

scholarly journals Analysis of Natural and Artificial Phenomena Using Signal Processing and Fractional Calculus

2015 ◽  
Vol 18 (2) ◽  
Author(s):  
J. A. Tenreiro Machado ◽  
António M. Lopes
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Vector Field ◽  
System Dynamics ◽  
Power Law ◽  
System Behavior ◽  
Amplitude Spectra ◽  
The Fourier Transform ◽  
Complex Phenomena ◽  
Power Law Parameters

AbstractIn this paper we study several natural and man-made complex phenomena in the perspective of dynamical systems. For each class of phenomena, the system outputs are time-series records obtained in identical conditions. The time-series are viewed as manifestations of the system behavior and are processed for analyzing the system dynamics. First, we use the Fourier transform to process the data and we approximate the amplitude spectra by means of power law functions. We interpret the power law parameters as a phenomenological signature of the system dynamics. Second, we adopt the techniques of non-hierarchical clustering and multidimensional scaling to visualize hidden relationships between the complex phenomena. Third, we propose a vector field based analogy to interpret the patterns unveiled by the PL parameters.

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