Stress–strain properties of linear aromatic polyesters in the nonlinear viscoelastic range

The stress–strain curves for a series of linear aromatic polyesters were curve‐fitted to yield constant parameters for the one‐dimensional and three‐dimensional constitutive equations for nonlinear viscoelastic properties. Using these constants, the stress–strain curves could be reconstituted somewhat better by the one‐dimensional equations, but the agreement with the three‐dimensional curves was good. The same constants can be used to predict creep and stress–relaxation, the data for which are in a companion paper.