Structural Evolution of Crystalline Scaffolds and Ionic Domains in Polyethylene and Ethylene/Methacrylic Acid Copolymer Blend Blown Films

Understanding the cooperative role of flow and ionic interactions in governing crystallization in ionomer-modified polyethylene remains an unresolved challenge in polymer physics. In this study, we employ in situ synchrotron SAXS/WAXS to elucidate the structural evolution of PE/EMMA blown films processed under a wide range of take-up ratios (TUR) from 10 to 25. The results reveal a three-stage structural pathway, beginning with flow-induced precursors and chain entanglements (Region I), followed by lamellar nucleation coupled with the alignment of ionic aggregates that produce equatorial SAXS streaks (Region II), culminating in the formation of highly oriented crystalline scaffold networks that are preserved after solidification (Region III). We identified ionic aggregates as active structural participants rather than passive fillers, noting that their alignment under elongational flow mediates scaffold development and introduces mesoscale density fluctuations absent in neat PE. Increasing TUR systematically shifts scaffold formation upward in the bubble, suppresses final crystallinity by restricting chain folding, and yet enhances orientation through accelerated flow-driven alignment. These findings establish a unified framework that links ionic domain dynamics, flow-induced crystallization, and scaffold locking in blown films, providing mechanistic insight into ionomer–polyethylene blends and advancing strategies for tailoring industrial film processing.