G(t): General description

Purpose

Data Files

  • The first line of the file should contain the sample parameters separated by semi-colons (;). It may contain any number of parameters which will be read and saved as file-parameter in RepTate. In unit-aware applications, a file parameter value may also include an explicit unit, for example Mw=1131 Da;T=25 ºC;gdot=0.1 1/s;.

  • Then the data columns should appear, separated by spaces or tabs.

  • In unit-aware applications, column headers may include units in square brackets or parentheses, for example t [min] or G' [kPa]. See Units for the supported units and current limitations.

.gt extension

Text files with .gt extension should be organised as follows:

  • .gt files should provide at least parameter values for

    1. Molecular weight, \(M_w\)

    2. Strain applied, \(\gamma\). If not present, the experimental data file is supposed to contain the relaxation modulus, not the stress, and the value of \(\gamma\) is assumed to be equal to 1.

  • 2 columns separated by spaces or tabs containing respectively:

    1. time, \(t\),

    2. shear stress, \(\sigma_{xy}\),

A correct .gt file looks like:

Mw=224;gamma=1;
t sxy
0.0E+0      1.28146E+10
5.0E-6      1.13402E+10
1.0E-5      7.57171E+9
...         ...

Views

log[G(t)]

../../../_images/Gt_LogGt.png

G(t)

../../../_images/Gt_Gt.png

Schwarzl G’,G’’

The time range of the \(G(t)\) that will be used for the Fourier transformation can be selected by changing the values of the text boxes \(\log(t_{min})\) and \(\log(t_{min})\). For more details, check [1].

../../../_images/Gt_Schwarzl.png

i-Rheo G’,G’’

The time range of the \(G(t)\) that will be used for the Fourier transformation can be selected by changing the values of the text boxes \(\log(t_{min})\) and \(\log(t_{min})\). For more details, check [2].

../../../_images/Gt_iRheo.png

i-Rheo-Over G’,G’’

The time range of the \(G(t)\) that will be used for the Fourier transformation can be selected by changing the values of the text boxes \(\log(t_{min})\) and \(\log(t_{min})\). For more details, check [2].

../../../_images/Gt_iRheoOver.png

References

[1]

F. R. Schwarzl. Numerical calculation of storage and loss modulus from stress relaxation data for linear viscoelastic materials. Rheologica Acta, 10(2):165–173, jun 1971. doi:10.1007/bf02040437.

[2] (1,2)

Manlio Tassieri, Marco Laurati, Dan J. Curtis, Dietmar W. Auhl, Salvatore Coppola, Andrea Scalfati, Karl Hawkins, Phylip Rhodri Williams, and Jonathan M. Cooper. I-rheo: measuring the materials\textquotesingle linear viscoelastic properties \textquotedblleft in a step\textquotedblright ! Journal of Rheology, 60(4):649–660, jul 2016. doi:10.1122/1.4953443.

[3]

Sachin Shanbhag. pyReSpect: A Computer Program to Extract Discrete and Continuous Spectra from Stress Relaxation Experiments. Macromolecular Theory and Simulations, 28(3):1900005, 2019. doi:10.1002/mats.201900005.