Bio-based multilayer packaging recycling via solvent delamination and selective dissolution

Overview

Multilayer packaging films deliver superior product protection by combining the unique properties of multiple polymers and additives, but their tightly bonded structures make recycling extremely difficult. This research program targets the recycling of bio-based multilayer packaging through a two-stage approach: solvent-driven delamination of bonded layers into individual films, followed by selective dissolution to separate and recover the constituent polymers for reprocessing into new products. The approach is designed to be energy-efficient and low in greenhouse gas emissions because it preserves most of the polymer content in its original state with minimal degradation.

The research team has demonstrated proof-of-concept delamination of conventional multilayer films, including PE/PET, LLDPE/Nylon 6, LLDPE/EVOH, and HDPE/EVOH combinations, using a variety of solvents. They have also achieved separation of similar polymer mixtures such as polyolefins via selective dissolution. This expertise is now being extended to bio-based multilayer packaging systems containing polymers such as PLA and PHA.

Technical specifications

Delamination approach:

• Solvent-based reduction of adhesion between adjacent layers through physical mobilization or dissolution of macromolecules at the layer interface
• Chemical modification at the interface to weaken bonding
• Non-polymer materials and contaminants are removed during processing

Polymer separation and recovery:

• Density-based separation and flotation techniques for fractionating polymer types
• Selective dissolution using solvents capable of dissolving bio-based polymers such as PLA and PHA
• Initial proof of concept with halogenated solvents, transitioning to non-volatile, environmentally responsible Switchable-Hydrophilicity Solvents
• Polymer recovery as solid residues without the use of antisolvents
• Solvent recovery protocols for process scale-up

Key advantages:

• Low energy input compared to mechanical or thermal recycling methods
• Minimal polymer degradation preserves material properties
• Compatibility with bio-based polymers including PLA and PHA
• Removes non-polymer contaminants during processing

Technology readiness level

The technology is at an early-to-mid stage of development. Delamination of conventional multilayer film systems has been demonstrated in laboratory settings, and separation of similar polymer mixtures via selective dissolution has been achieved. Extension to bio-based multilayer packaging is the current focus, with ongoing work targeting PLA- and PHA-containing films. Future validation steps include demonstrating hybrid delamination and separation techniques, evaluating recovered polymer properties, and developing solvent recovery processes for scale-up. The approach is ready for collaborative research partnerships to advance toward pilot-scale validation.