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.

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.

Dynamic Viscoelastic Properties of SBS Modified Asphalt Based on DSR Testing

2012 ◽  
Vol 598 ◽  
pp. 473-476 ◽  
Author(s):  
Yong Mei Guo ◽  
Wei Chen
Keyword(s):  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Frequency Range ◽  
Master Curves ◽  
Temperature Property ◽  
Low Frequencies ◽  
High Temperature Property ◽  
Frequency Sweeps

Five SBS modified asphalts and one base asphalt were selected to carry out frequency sweeps over a wider frequency range using the dynamic shear rheometer (DSR). Six asphalt binders were subjected to sinusoidal loading at 30°C-90°C within the linear viscoelastic limits, and master curves of complex modulus (G*) and phase angle (δ) could be constructed by means of the time-temperature superposition principle (TTSP). The results show that the G* values of SBS modified asphalts are significantly greater than those of base asphalt at low frequencies, but are slightly smaller at high frequencies. Compared with the base asphalt, SBS modified asphalts have narrower master curves of complex modulus, and their phase angles are much smaller within the whole frequency range. This indicates that various properties of SBS modified asphalts, such as high-temperature property, low-temperature property, temperature susceptibility and elastic recoverability, are superior to those of the base asphalt. The G* values of the rolling thin-film oven (RTFO) aged asphalt are larger than those of the unaged asphalt in the whole range of frequencies, demonstrating that the anti-rutting performance of asphalt binder is improved after short-term aging.

Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition

1997 ◽  
Vol 1570 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Sun Woo Park ◽  
Y. Richard Kim
Keyword(s):  
Linear Viscoelasticity ◽  
Superposition Principle ◽  
Asphalt Mixture ◽  
Temperature Shift ◽  
Relaxation Modulus ◽  
Analytical Description ◽  
Shift Factor ◽  
Temperature Correction ◽  
Temperature Superposition ◽  
Time Temperature Superposition

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.

S0406-3-4 Determination of Time-temperature Shift Factor for Accelerated Testing of CFRP

2009 ◽  
Vol 2009.1 (0) ◽  
pp. 345-346
Author(s):  
Makoto OGATA ◽  
Katsuya FUKUSHIMA ◽  
Hongneng CAI ◽  
Masayuki NAKADA ◽  
Yasushi MIYANO
Keyword(s):  
Temperature Shift ◽  
Shift Factor ◽  
Accelerated Testing

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.

Effect of Saturation Pressure on Equivalency of Decompression Time and Foaming Temperature on Cell Density of Foamed Polystyrene

2007 ◽  
Vol 26 (5) ◽  
pp. 295-304 ◽  
Author(s):  
Susumu Nakano ◽  
Minoru Shimbo ◽  
Akihiro Misawa
Keyword(s):  
Cell Growth ◽  
Temperature Dependence ◽  
Cell Density ◽  
Saturation Pressure ◽  
Temperature Shift ◽  
Shift Factor ◽  
Saturation State ◽  
Decompression Rate ◽  
Foaming Temperature ◽  
Decompression Time

In this paper, the effect of saturation pressure on the time-temperature equivalent law of the decompression rate (decompression time) and foaming temperature of the cell density, the number of cells per unit volume remaining in foamed plastic was discussed. The foaming was carried out in the method described be by using batch foaming process. The blowing agent was soaked into the resin as a solid state at various high saturation pressures under temperatures higher than the glass transition temperature of the resin. After foaming agent reached its saturation state, cell nucleation and cell growth were accelerated by decompression. Finally, cell growth was halted by cooling. The polystyrene (PS) specimens were foamed under the various saturation pressures, foaming temperatures and decompression rates. The following results were obtained. (1) Cell density of foamed PS shows time and temperature dependence as follows. The cell density increases when the decompression rate is quick, i.e. the decompression time is shortened at the condition of low foaming temperature, and cell density decreases when the decompression rate is slow, i.e. decompression time is lengthened at the condition of high foaming temperature under various saturation pressures. (2) The time-temperature equivalent law is maintained between the time dependence and temperature dependence of the cell density of foamed PS, and it can expressed with the same time-temperature shift factor if the decompression rate is the same even if saturation pressure changes.

Stress Relaxation Behavior of Ethylene Propylene-Hexadiene Terpolymers

1971 ◽  
Vol 44 (4) ◽  
pp. 1057-1064
Author(s):  
C. K. Shih
Keyword(s):  
Stress Relaxation ◽  
Abrupt Change ◽  
Temperature Shift ◽  
Shift Factor ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Ethylene Propylene ◽  
Wlf Equation ◽  
Ethylene Content ◽  
Higher Temperature

Abstract 1. The stress relaxation behavior of E/P/hexadiene polymer over wide temperature [Tg to (Tg+140°C)] and composition (molar E/P = 1.7 to 4.4) ranges is described. 2. Although Tg of the polymers is essentially constant (− 60° C), the onset temperature for rubbery flow characterized by an abrupt change in the rate of stress relaxation is highly dependent upon composition. It increases to a higher temperature as the ethylene content is increased. It is also affected by the catalysts used for polymer synthesis. 3. The time-temperature shift factor for one sample was found to follow the WLF equation over the temperature range from − 50° C to 0° C.

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