Recyclable Multi-Layer Films from Virgin and Recycled Polyethylene

Flexible multilayer films are indispensable in food packaging, but their complex composition makes recycling significantly more difficult. To support a circular packaging economy, this study investigates mono-material multilayer films based entirely on polyethylene (PE), incorporating both virgin and recycled feedstocks.

Several three-layer films were fabricated via film blowing extrusion using ultra-low-density polyethylene (ULDPE), post-consumer recycled low-density polyethylene (rLDPE), and their blends. A comprehensive set of characterizations was conducted, including differential scanning calorimetry, thermogravimetric analysis, and melt flow index to assess thermal and molecular properties, as well as mechanical testing (tensile, tear, and dart drop impact). Proxy-based migration experiments were conducted to determine contamination risks relevant to food-contact applications.

Molecular analyses revealed opposing degradation mechanisms: chain scission in ULDPE and crosslinking in rLDPE. The rLDPE showed higher crystallinity, contributing to mechanical robustness when combined with ULDPE. Mechanical tests indicated that increasing rLDPE content reduces ductility and impact strength, though moderate levels preserve acceptable performance. Migration testing confirmed no detectable proxy contaminant transfer through virgin outer layers down to 10 μm thickness, even in films with 75% recycled content.

Controlled blending of rLDPE and ULDPE enables the design of recyclable, mono-material multilayer films with tailored mechanical and barrier properties. The findings suggest that high recycled content can be safely used in packaging, provided design-for-recycling principles are applied. This work highlights a viable strategy for integrating post-consumer waste into high-performance flexible packaging.