Application of the time-temperature equivalence at large deformation to describe the mechanical behavior of polyethylene-based thermoplastic, thermoset and vitrimer polymers

This study applies a mechanical approach based on time-temperature equivalence to relate chain networks and properties of polyethylene-based materials (HDPE, PEXb, and especially vitrimers). We first characterize the chain network behavior from the microscopic to mesoscopic level using solvent extraction, DSC, DMTA, and rheology. The chain networks can be distinguished from the cross-linking degree, degree of crystallinity, and time-temperature-dependent linear viscoelasticity in solid state or above melting temperatures. As core studies, we then properly characterize the tensile mechanical behavior at large deformation. PEXb is stiffer than HDPE and PE-vitrimer at all tested physical states (from viscoelastic to flow states). Tensile mechanical behaviors between PE-vitrimer and HDPE are i) equivalent at the end of the glassy state (i.e., lower temperatures or high equivalent strain rates), and ii) distinct approaching flow (i.e., higher temperature or low equivalent strain rates). Therefore, an approach based on the time-temperature superposition extended to large deformation is suitable to link material properties to the chain networks.