A Worked Example of Time Temperature Superposition Data

The basics of WLF theory are applied here to actual data.

The data is collected over a time scale range from 10 seconds to 10,000 secs (~2 hrs 45 mins) and over a temperature range from -83 C to -40 C.

The isotherms can be joined together, to form a "long function" which is also an isotherm, ranging over a time scale from 10 seconds to 1,000,000,000,000 seconds (~30 centuries.)

A time temperature graph is a log-log plot of a time dependent, temperature dependent property vs. time. decades of time, and these can be fitting one against the other to form a curve similar to the viscoelastic curve. In the above graph, each isotherm is illustrated with a unique color. In the graph below you can see that curves are constructed by bringing the different isotherms together to form longer functions. This second graph was constructed from the graph above.

The larger version of the above graph is very likely to crash due to its size
Time-Temperature Superposition relates to the WLF equation.

Definitions isotherm-- a collection of data points, all taken at the same temperature.

decade-- decade refers to the spacing on the log plot. The range (1, 10, 100) is said to span two decades, where going from 1 to 10 (10^0 to 10^1) is the first decade and 10 to 100 (10^1 to 10^2) is the second decade.

Last Update- June 29, 1995- wld