Sustainable Engineering of Materials and Processes for Flexible Packaging

Flexible packaging offers lightweight protection but is dominated by multilayer laminates that hinder recycling. This PhD addresses the sustainability gap by integrating material design, process optimization, and end-of-life strategies for industrial films. A survey of commercial structures – from Polyethylene Therephthalate (PET)/Polyethylene (PE) and Polyamide (PA)/PE laminates to emerging mono-material polyolefins – was built using complementary characterization: spectroscopy, thermal and morphological analysis, and barrier assessment. This work identified a three-axis strategy targeting bio-based, mono-material, and multi-material systems, each with distinct Technology Readiness Level (TRL) and sustainability challenges. At the lowest TRL, bio-based polymers such as PLA were explored as renewable alternatives. Crystallinity control, blending, composite manufacturing, and irradiation highlighted pathways to overcome Polylactic Acid (PLA)’s brittleness and poor barrier properties. Combined strategies showed potential to balance flexibility and performance for food packaging. At an intermediate TRL, mono-material polyolefin structures were optimized for sealing. Industrial Horizontal Form Fill Seal (HFFS) trials proved that impulse-heating improved PE sealing strength and enabled Polypropylene (PP) process windows at commercial speeds, supporting recyclable monomaterials as replacements for laminates. At the highest TRL, conventional laminates were tackled with a hybrid chemical–mechanical recycling route: glycolysis to recover PET, dissolution to isolate PA, and re-extrusion of polyolefins. Recovered fractions were compatible with repolymerization or secondary valorization. Overall, this work demonstrates tailored strategies: material innovation for biopolymers, process optimization for mono-materials, and novel recycling for multi-materials – providing a foundation for packaging that reconciles functionality and circularity.