Evaluating the Effects of Mechanical Recycling on Molecular Architecture and Functional Performance in Polyethylene Films

ABSTRACT Recycling polyethylene (PE) remains challenging due to its environmental persistence and property degradation during reprocessing. This study examines how mechanical recycling can enhance gas and moisture barrier performance in PE blown films through structural modifications in the amorphous phase. Unimodal and bimodal PE resins were recycled via blown film extrusion, simulating industrial packaging conditions. Comprehensive characterization, including gel permeation chromatography, rheology, birefringence, and gas transmission analysis, revealed that recycled unimodal PE exhibited increased z‐average molecular weight and long‐chain branching, attributed to antioxidant depletion. These changes were associated with enhanced melt elasticity and amorphous phase orientation, resulting in a 23% lower water vapor transmission rate (WVTR) and a 16% lower oxygen transmission rate (OTR), despite minimal changes in crystallinity. In contrast, bimodal PE showed negligible structural or functional changes. These findings provide additional insight into the structure–property relationship for improving barrier properties in recycled PE, reflecting the combined effects of processing‐induced orientation and molecular changes in the amorphous phase. This suggests a design strategy for molecular architectures that support high‐performance reuse in circular polymer systems.