Assessing mechanical recyclability of blown films and integration of PCR for high modulus uniaxially drawn PE film application

• Multiple extrusion reduced crystallinity and enhancement of modulus. • MDO films showed high MD modulus with fibrillar orientation. • MD modulus improved 4.3 times in stretched virgin blend films. • Reprocessed MDO films retained almost 77% of virgin MD modulus. • At 5% PCR, MDO films matched virgin film tensile modulus. Multi-material multi-layer plastic packaging, widely used in packaging of fast-moving consumer goods (FMCG), presents significant challenges for mechanical recycling due to its complex composition. These packages often consist of multiple layers of various polymers and metals, making traditional recycling methods ineffective. To address this, a shift toward mono-material multi-layer packaging has gained attention, particularly in polyethylene (PE) based mono-material multi-layer flexible packaging. Traditionally, the outer layer of multi-material flexible packaging is made from non-PE materials like polyethylene terephthalate (PET) and polyamide (PA) for enhanced stiffness and barrier properties. However, orienting polymer films through processes like machine direction orientation (MDO) has the potential to improve both mechanical and barrier properties, facilitating the development of lightweight, mono-material packaging. This study examines the mechanical recyclability of virgin polyethylene (PE) blown films and the incorporation of post-consumer resin (PCR) for subsequent machine direction orientation (MDO) operation, intended for use in the outer layer of mono-material flexible packaging. Two set of experiments were conducted. The first set assessed the recyclability of virgin PE blown films after two reprocessing cycles, revealing that slight molecular degradation affected the crystallinity and tensile modulus of reprocessed films. Despite these changes, the reprocessed films retained approximately 77% of the tensile modulus of virgin MDO films. The second study integrated mixed polyolefin PCR into virgin PE blends at 5% and 30% by weight. The 5% PCR blend demonstrated a tensile modulus comparable to virgin MDO films, highlighting its potential for high-end packaging applications like mono-material PE based flexible packaging. This research supports the feasibility of using recycled materials in MDO processes for stiffness enhanced outer layer of mono-material PE based flexible packaging.