Semicrystalline polyamide 6 (PA6) exhibits a strong dependence of its thermo-mechanical response on thermal history and evolving morphology. During thermoforming and related processes, the material transitions from a molten state to a solid viscoelastic state whose behavior is governed by the development of crystallinity. This dissertation establishes an experimental and modeling framework that addresses these two key aspects: crystallization during cooling and the viscoelastic behavior of the solid polymer at constant crystallinity. The crystallization behavior of PA6 is characterized over a wide range of cooling conditions, and the resulting kinetics are represented through a model suitable for use in process simulations. The linear viscoelastic response of PA6 with controlled crystallinity is analyzed in the frequency domain, enabling the construction of master curves and the identification of relaxation spectra. In a separate study, a thermodynamically consistent finite-strain viscoelastic model is extended to capture time- and rate-dependent deformation in the solid state and is calibrated using mechanical tests. Together, these contributions provide a coherent description of the thermo-mechanical behavior of PA6 from melt to solid. The resulting models support predictive simulation of thermoforming processes and improve understanding of how crystallization and viscoelasticity jointly influence the performance of semicrystalline polymers.     «

Semicrystalline polyamide 6 (PA6) exhibits a strong dependence of its thermo-mechanical response on thermal history and evolving morphology. During thermoforming and related processes, the material transitions from a molten state to a solid viscoelastic state whose behavior is governed by the development of crystallinity. This dissertation establishes an experimental and modeling framework that addresses these two key aspects: crystallization during cooling and the viscoelastic behavior of the s...     »