An empirical equation on a shift factor for synthesizing master curves from nonlinear viscoelasticity functions based on free volume (abstract)

1992 ◽  
Vol 36 (5) ◽  
pp. 976-976
Author(s):  
Takuji Yamaguchi ◽  
Susumu Saeki ◽  
Junpei Yamanaka
Keyword(s):  
Free Volume ◽  
Empirical Equation ◽  
Nonlinear Viscoelasticity ◽  
Shift Factor ◽  
Master Curves

scholarly journals Identification of the Fractional Zener Model Parameters for a Viscoelastic Material over a Wide Range of Frequencies and Temperatures

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7024
Author(s):  
Zdzisław M. Pawlak ◽  
Arkadiusz Denisiewicz
Keyword(s):  
Viscoelastic Material ◽  
Shift Factor ◽  
Model Parameters ◽  
Master Curves ◽  
Zener Model ◽  
Horizontal Shift ◽  
Wide Range ◽  
Different Temperatures ◽  
Feasible Solutions ◽  
Fractional Zener Model

The paper presents an analysis of the rheological properties of a selected viscoelastic material, which is dedicated to the reduction of vibrations in structures subjected to dynamic loads. A four-parameter, fractional Zener model was used to describe the dynamic behavior of the tested material. The model parameters were identified on the basis of laboratory tests performed at different temperatures and for different vibration frequencies. After proving that the material is thermoreologically simple, the so-called master curves were created using a horizontal shift factor. The Williams–Landel–Ferry formula was applied to create graphs of the master curves, the constants of which were determined for the selected temperature. The resulting storage and loss module functions spanned several decades in the frequency domain. The parameters of the fractional Zener model were identified by fitting the entire range of the master curves with the gradientless method (i.e., Particle Swarm Optimization), consisting in searching for the best-fitted solution in a set of feasible solutions. The parametric analysis of the obtained solutions allowed for the formulation of conclusions regarding the effectiveness of the applied rheological model.

Equivalent Time Temperature Model for Physical Aging and Temperature Effects on Polymer Creep and Relaxation

2004 ◽  
Vol 126 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Ever J. Barbero ◽  
Kevin J. Ford
Keyword(s):  
Physical Aging ◽  
Temperature Shift ◽  
Shift Factor ◽  
Master Curves ◽  
Nonuniform Temperature ◽  
Equivalent Time ◽  
Temperature Method ◽  
Temperature Superposition ◽  
Term Data

The equivalent time temperature method (ETT) is a novel extension of the equivalent time method. ETT is developed in this work to deal with time-temperature shifting of long-term polymer and polymer composite creep data, including the effects of physical aging at nonuniform temperature. Modifications to classical testing methods and protocols are presented to obtain accurate and repeatable data that can support long-term predictions with nonuniform temperature conditions through time. These techniques are used to generate momentary Time temperature superposition (TTSP) master curves, temperature shift factor rates, and aging shift factor rates. Novel interpretation and techniques are presented to deal with the coupled age-temperature behavior over long times. Validation of predictions against over 20,000 Hr of long-term data in field conditions is presented.

Frequency-dependent viscoelastic properties of Chinese fir (Cunninghamia lanceolata) under hygrothermal conditions. Part 2: moisture desorption

Holzforschung ◽  
2019 ◽  
Vol 73 (8) ◽  
pp. 737-746 ◽  
Author(s):  
Tianyi Zhan ◽  
Jiali Jiang ◽  
Jianxiong Lu ◽  
Yaoli Zhang ◽  
Jianmin Chang
Keyword(s):  
Shift Factor ◽  
Chinese Fir ◽  
Cunninghamia Lanceolata ◽  
Damping Properties ◽  
Master Curves ◽  
Frequency Dependent ◽  
Wood Stiffness ◽  
Set Up ◽  
Stiffness And Damping ◽  
Moisture Desorption

AbstractThe frequency-dependent viscoelasticity of Chinese fir (Cunninghamia lanceolata) during moisture desorption was investigated and the applicability of the time-moisture superposition (TMS) relation on wood stiffness and damping during the moisture desorption was verified. The hygrothermal conditions for the moisture desorption were set up as six constant temperatures ranging from 30 to 80°C and three relative humidity (RH) levels at 0, 30 and 60%. Due to the elimination of water during the moisture desorption, the stiffness of the Chinese fir increased, whereas the damping decreased. With the increase in frequency, increased stiffness and decreased damping were observed. Utilizing the TMS relation, it was possible to construct master curves of wood stiffness at temperatures ranging from 30 to 80°C. The linear relationship between the shift factor and the moisture content (MC) manifested a low intermolecular cooperativity between the polymers and a narrow relaxation window. However, the TMS relation was not able to predict the wood damping properties during the moisture desorption, because wood is a multi-relaxation system. The non-proportional relationship between the free volume and MC during the moisture desorption may also explain why the TMS relation failed to construct master curves of the wood damping properties.

scholarly journals Rheological Characterization and Modeling of Thermally Unstable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2294
Author(s):  
Silvia Lajewski ◽  
Annika Mauch ◽  
Kalman Geiger ◽  
Christian Bonten
Keyword(s):  
Temperature Shift ◽  
Processing Parameters ◽  
Shift Factor ◽  
Master Curves ◽  
Plastic Pollution ◽  
High Activation ◽  
Rheological Characterization ◽  
Rheological Measurement ◽  
Frequency Sweeps ◽  
High Temperature Sensitivity

Presently, almost every industry uses conventional plastics. Its production from petroleum and extensive plastic pollution cause environmental problems. More sustainable alternatives to plastics include bioplastics such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), which is produced by bacteria and is biodegradable even in seawater. High temperature sensitivity as well as massive thermal degradation cause difficulties during the processing of PHBV. The aim of this work is to create a detailed rheological characterization and master curves to gain deeper knowledge about the material and its processing parameters. The rheological characterization was performed with frequency sweeps in the range of 0.1 rad/s to 628 rad/s and time sweeps over 300 s. Creating master curves at the reference temperature of 180 °C with the software IRIS delivers Carreau and Arrhenius parameters. These parameters allow for a calculation of the master curves for all other temperatures by means of the temperature shift factor. Moreover, the rheological measurements reveal a minimum rheological measurement temperature of 178 °C and a surprisingly high activation energy of 241.8 kJ/mol.

FREE VOLUME CHANGE OF METALLIC GLASSES STUDIED BY THERMAL EXPANSION MEASUREMENTS

1980 ◽  
Vol 41 (C8) ◽  
pp. C8-875-C8-877
Author(s):  
E. Girt ◽  
P. Tomić ◽  
A. Kuršumović ◽  
T. Mihać-Kosanović
Keyword(s):  
Thermal Expansion ◽  
Free Volume ◽  
Volume Change ◽  
Metallic Glasses

Survey of Relations of Chemical Constituents in Polymer-Based Materials with Brittleness and its Associated Properties

2016 ◽  
Vol 10 (4s) ◽  
pp. 595-600 ◽  
Author(s):  
Witold Brostow ◽  
◽  
Haley E. Hagg Lobland ◽  
Keyword(s):  
Chemical Composition ◽  
Impact Strength ◽  
Free Volume ◽  
Chemical Constituents ◽  
Polymer Processing ◽  
Brittle Behavior ◽  
Composition And Structure ◽  
Common Thread

The property of brittleness for polymers and polymer-based materials (PBMs) is an important factor in determining the potential uses of a material. Brittleness of polymers may also impact the ease and modes of polymer processing, thereby affecting economy of production. Brittleness of PBMs can be correlated with certain other properties and features of polymers; to name a few, connections to free volume, impact strength, and scratch recovery have been explored. A common thread among all such properties is their relationship to chemical composition and morphology. Through a survey of existing literature on polymer brittleness specifically combined with relevant reports that connect additional materials and properties to that of brittleness, it is possible to identify chemical features of PBMs that are connected with observable brittle behavior. Relations so identified between chemical composition and structure of PBMs and brittleness are described herein, advancing knowledge and improving the capacity to design new and to choose among existing polymers in order to obtain materials with particular property profiles.

Parameters of the free volume theory in glasses with trigonal local coordination

2001 ◽  
Vol 10 (0) ◽  
pp. 147-151
Author(s):  
Т. М. Мельниченко ◽  
Т. Д. Мельниченко ◽  
Я. Я. Коцак ◽  
Я. П. Куценко ◽  
П. П. Пуга
Keyword(s):  
Free Volume ◽  
Free Volume Theory ◽  
Local Coordination
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