Relaxation time(s) and the relaxation time spectrum H(λ) of a polypropylene melt

Relevant for: Polymer melts, Maxwell Fluid, Regularization Method, Relaxation Time, Carreau-Yasuda Regression, Relaxation-time-spectrum, Rouse Motions


The relaxation time spectrum H(λ) is the rheological equivalent of the molar mass distribution MMD.

It is a mathematical model based on the theory that a "rheologically simple" viscoelastic liquid without branching, cross linkage or gel character can easily be simulated by a combination of Maxwell elements (spring and dashpot).

The present application note explains how to calculate the "relaxation time spectrum" from a frequency sweep using the so called "regularization method". Furthermore it is shown how a general "relaxation time" can be calculated based on the Carreau-Yasuda regression.

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