Here is a calibrated material model for a SABIC polypropylene (58MNK10) tested at 5 deg C. To use this material model you will need to first install the MCalibration software, and then export the model to your favorite FE software. The calibrated material model is the PolyUMod Three Network (TN) model.
Tutorial on how to make the PolyUMod TN and TNV models better capture the stiffness non-linearity before yielding.
The Arruda-Boyce Eight-Chain model is a micromechanism-inspired hyperelastic model that works very well. This article explains the theory.
Tutorial on Abaqus creep laws, which 2 you should not use, and which are the best. I also discuss how creep models work for polymers.
