Dynamic mechanical study of four amorphous polymers around and above the glass transition: breakdown of the time-temperature superposition principle in the frame of the coupling model

1991 ◽  
Vol 24 (18) ◽  
pp. 5196-5202 ◽  
Author(s):  
A. Alegria ◽  
E. Macho ◽  
J. Colmenero
Keyword(s):  
Glass Transition ◽  
Superposition Principle ◽  
Coupling Model ◽  
Amorphous Polymers ◽  
Dynamic Mechanical ◽  
Mechanical Study ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

Integration of Atomistic Simulation with Experiment Using Time−Temperature Superposition for a Cross-Linked Epoxy Network

2019 ◽  
Author(s):  
Ketan Khare ◽  
Frederick R. Phelan Jr.
Keyword(s):  
Master Curve ◽  
Glassy State ◽  
Superposition Principle ◽  
Quantitative Comparison ◽  
Time Shift ◽  
Data Sets ◽  
Epoxy Network ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

<a></a><a>Quantitative comparison of atomistic simulations with experiment for glass-forming materials is made difficult by the vast mismatch between computationally and experimentally accessible timescales. Recently, we presented results for an epoxy network showing that the computation of specific volume vs. temperature as a function of cooling rate in conjunction with the time–temperature superposition principle (TTSP) enables direct quantitative comparison of simulation with experiment. Here, we follow-up and present results for the translational dynamics of the same material over a temperature range from the rubbery to the glassy state. Using TTSP, we obtain results for translational dynamics out to 10<sup>9</sup> s in TTSP reduced time – a macroscopic timescale. Further, we show that the mean squared displacement (MSD) trends of the network atoms can be collapsed onto a master curve at a reference temperature. The computational master curve is compared with the experimental master curve of the creep compliance for the same network using literature data. We find that the temporal features of the two data sets can be quantitatively compared providing an integrated view relating molecular level dynamics to the macroscopic thermophysical measurement. The time-shift factors needed for the superposition also show excellent agreement with experiment further establishing the veracity of the approach</a>.

scholarly journals Designing a New Dynamic Mechanical Analysis (DMA) System for Testing Viscoelastic Materials at High Frequencies

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Roja Esmaeeli ◽  
Haniph Aliniagerdroudbari ◽  
Seyed Reza Hashemi ◽  
Chiran JBR ◽  
Siamak Farhad
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Material Properties ◽  
High Frequency ◽  
Superposition Principle ◽  
Mechanical Analysis ◽  
Viscoelastic Materials ◽  
High Frequencies ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

The aim of this study is to design a new dynamic mechanical analysis (DMA) measurement system that can operate for shear tests at frequencies as high as 10 kHz with strain amplitudes sufficient for viscoelastic materials operating in high-frequency deformation applications, such as tire rubbers. The available DMA systems in market cannot effectively operate for accurate and direct measurement of viscoelastic material properties for applications dealing with high-frequency deformation of materials. Due to this, the available DMA systems are used for indirect measurements at low frequencies and low temperatures, followed by using time-temperature superposition principle to predict the properties at high frequencies. The goal of this study is to make the range of the test broad enough to eliminate the use of the time-temperature superposition principle in the determination of properties of viscoelastic materials. Direct measurement of viscoelastic material properties and increasing the accuracy of results are the main motivations to design a new DMA system. For this purpose, the state-of-the-art technologies to achieve high frequencies and strain amplitudes as well as instrumentation and control of the system are studied. The design process is presented in this paper.

Sign in / Sign up

Export Citation Format

Share Document