Mechanical and Thermal Characterization of Polyoxymethylene: Strain Rate Sensitivity, Crystallinity and Failure Mechanisms

Polyoxymethylene (POM) is a high-performance semi-crystalline thermoplastic widely used for its excellent mechanical strength, wear resistance, and dimensional stability. This study investigates the mechanical and thermal behavior of POM under large deformations through tensile testing and thermal analysis. The results indicate that POM exhibits linear elastic behavior at low strains, transitioning to nonlinear viscoelastic and plastic behavior at higher deformations. Stress whitening and microvoid formation significantly influence failure mechanisms. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) confirm POM’s high crystallinity (~40%) and thermal stability, with a melting temperature of 166°C. Scanning Electron Microscopy (SEM) reveals cavitation and fibrillation as dominant damage mechanisms. The findings highlight the challenges of substituting POM due to its unique property balance. Further research should focus on predictive plasticity models to optimize POM’s industrial applications.