Model treatment of tensile deformation of semicrystalline polymers: Static elastic moduli and creep parameters derived for a sample of polyethylene

A model constructed to treat tensile deformation of semicrystalline polymers introduced in a first paper is again applied to measurements on poly(ethylene-co-12% vinyl acetate) and is now used for an extraction of true elastic moduli and a discussion of the creep behavior. Elastic moduli vary in a characteristic manner during the stretching. There is first a decrease, with a maximum decay at the yield point, followed by an increase setting in with the formation of fibrils. Creep kinetics obey after a short initial period a log t law, which is reproduced by the model. A relation between creep and stress relation predicted by the model is confirmed by the experiments at lower strains.