A constitutive model for isotropic, semi-crystalline polymers is proposed. The model is Eulerian in the sense that it is independent of measures of total deformation, plastic/inelastic deformations, and all state variables are defined in the current state of the material. The deformation state of the material is represented by a unimodular tensor, characterizing elastic distortional deformation, and an elastic dilatation. The model is able to account for such essential phenomena as strain-rate dependence, work hardening, stress relaxation, volumetric inelastic deformations, and damage. Uniaxial tension tests were performed on polyoxymethylene (POM), which is a semi-crystalline polymer widely used in the industry. Three types of tests were conducted: monotonic loading tests at different strain rates, stress relaxation tests, and loading-unloading tests. These tests produced large elastic and inelastic deformations which were reproduced well by the model. The model was also implemented as a VUMAT in Abaqus, and the deformation of a 3D geometry was simulated. Specifically, a simple structure of the POM material was deformed and then unloaded. Thenresulting elastic spring-back and residual stress state was investigated.