Hybrid mechanical-chemical recycling technology for multilayered biodegradable polymer waste streams

Overview

This research program addresses one of the most pressing challenges in sustainable packaging: how to efficiently recycle multilayered biodegradable polymer films composed of immiscible polymers such as PLA, PBAT, and PHA. Current recycling streams often mix these polymers, producing contaminated outputs with limited reuse potential. The proposed technology applies hybrid mechanical-chemical separation techniques to recover individual polymer streams from mixed waste, enabling each fraction to be upcycled independently into higher-value products.

The approach offers significant value to packaging manufacturers, biopolymer producers, waste management companies, and brand owners seeking to meet circular economy targets and regulatory requirements for biodegradable materials. By enabling large-scale separation of polymer phases, this technology can reduce landfill dependence, lower reliance on virgin feedstock, and create new revenue streams from previously unrecyclable waste.

Technical specifications

Two complementary separation routes:

• Chain Extension Route: Increases phase separation and coalescence in the melt by chain-extending one polymer phase, creating high-viscosity droplets that can be mechanically filtered prior to the extrusion die. Current results show over 70% of the chain-extended polyester phase reaching filterable droplet sizes, with a target of 90% of droplets exceeding 10 microns in diameter.
• Depolymerization Route: Uses supercritical CO2-assisted melt processing to depolymerize polyester or polyamide phases and separate them from the main polyolefin stream. PET depolymerization rates above 98% have been achieved, with ongoing trials targeting 80% separation of the depolymerized phase.

Key capabilities:

• Twin-screw extrusion-based processing compatible with existing industrial equipment
• Machine learning-assisted multi-scale modeling to optimize catalyst geometry, chemistry, and separation efficiency
• Applicability to multiple biodegradable polymer combinations including PLA, PBAT, and PHA
• Scalable methodology building on validated results from polyolefin/polyester and polyolefin/polyamide systems

Technology readiness level

The underlying melt separation methodology has been validated on conventional polyolefin/polyester and polyolefin/polyamide waste streams, with promising results in both chain extension and depolymerization routes. Extension to biodegradable polymer systems represents an adaptation of proven techniques rather than unproven concepts. The proposed 18–24 month research program will involve 0.5 postdoctoral fellows and 2 PhD students working to identify optimal rheology modifiers, validate in-melt separation performance, and achieve large-scale separation exceeding 80% of individual polymer melt streams. This positions the technology at a mid-stage development level with strong potential for scale-up and industrial adoption.