Circular Quality of Polymers: Test-Based Evidence for Comparison of Bio-Based and Fossil-Based Polymers

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Engineering

Background:

• Achieving material circularity requires polymers retaining quality post-recycling to reduce virgin material dependency.
• The European Commission's Product Environmental Footprint (PEF) methodology uses economic models with default parameters for fossil-based polymer quality changes, but not bio-based ones.
• Existing methods for assessing polymer recyclability may not accurately reflect real-world technical quality degradation.

Purpose of the Study:

• To calculate the technical substitutability of recycled polymers based on their actual quality changes.
• To compare the recyclability of two fossil-based polymers (HDPE, PET) and two bio-based polymers (PLA, PHB).
• To evaluate the limitations of the economic substitutability method versus a test-based approach for polymer recycling.

Main Methods:

• Mechanical, processing, and optical properties were tested to assess quality changes in recycled polymers.
• A test-based example was developed for calculating technical substitutability.
• Multiple-cycle recycling scenarios were simulated to evaluate polymer degradation.

Main Results:

• The economic substitutability method yielded significantly different results compared to the test-based technical quality assessment.
• High-density polyethylene (HDPE) exhibited superior circular properties among the studied polymers.
• Bio-based polymers like PLA and PHB require further research regarding their quality changes during recycling before widespread adoption as substitutes for fossil-based plastics.

Conclusions:

• A harmonized testing methodology is crucial for accurately calculating quality degradation across all polymer types during recycling.
• The economic substitutability approach has significant limitations and does not fully capture the technical realities of polymer circularity.
• The study highlights the need to re-evaluate the substitution of fossil-based polymers with bio-based alternatives based on comprehensive recycling data.