Effect of Crosslink Density on the Non‐Isothermal Crystallization Behavior of Polyethylene Vitrimer

Abstract

Converting polyethylene (PE) into dynamic covalent networks represents a crucial pathway toward achieving sustainability in polyolefins. In this study, PE‐Vitrimers with gradient cross‐link densities were constructed, and their non‐isothermal crystallization behavior was systematically investigated using multiple kinetic models. It was found that the influence of the dynamic cross‐linked network on non‐isothermal crystallization is primarily manifested as a reshaping of the kinetic evolution pathway rather than thermodynamic disruption of the crystal structure. Although the introduction of the cross‐linked network does not alter the inherent orthorhombic crystal system of the PE matrix, the polar cross‐linking nodes enhance the Avrami exponent via heterogeneous nucleation effects and induce anisotropic crystal growth. Meanwhile, the steric hindrance arising from the dense topological network gradually dominates, leading to a monotonic decrease in the overall crystallization rate, accompanied by a global upward shift and a non‐monotonic decrease‐then‐increase evolution of the local crystallization activation energy with conversion. This work elucidates the physical competition mechanism between cross‐link‐induced heterogeneous nucleation and topological constraints, providing important theoretical support for the processing design of semi‐crystalline Vitrimer.