Overview

This talk explored polymer circularity, with a focus on polyolefins—particularly polyethylene and polypropylene—which dominate global plastic production but have extremely low recycling rates in the United States. The presentation outlined why traditional mechanical and chemical recycling face limitations for these materials and introduced upcycling strategies that convert polyolefin waste into higher-value, longer-lifetime materials. The work highlights how polymer chemistry and materials design can play a central role in reducing plastic waste while preserving the societal benefits of plastics.

 
Expert Insights & Key Takeaways

Polyolefins are critical but under-recycled
Polyolefins account for ~60% of global plastic production, yet most end up landfilled or mismanaged due to incompatibility issues, property degradation during recycling, and high energy costs associated with chemical recycling.

Upcycling offers a pathway beyond traditional recycling
Rather than returning plastics to their original form or breaking them into fuels, upcycling transforms waste polymers into materials with new functionality and longer service lifetimes, keeping value within the economy.

Thermoset polyurethanes from polyolefin waste
The research demonstrated a route to convert polypropylene into cross-linked polyurethane thermosets, enabling applications in durable goods such as insulation, coatings, and structural materials—sectors with significantly longer product lifetimes.

Industry-relevant processing is essential
Functionalization and curing strategies were designed to be compatible with melt extrusion, avoiding solvent-based chemistry and aligning with existing industrial polymer processing infrastructure.

Polypropylene crystallinity is retained in the network
Despite forming a three-dimensional polyurethane network, polypropylene segments retain their semi-crystalline structure, with crystallization behavior similar to virgin polypropylene across multiple length scales.

Dynamic cross-linking enables reprocessability
Incorporating urethane exchange catalysts allows thermoset polyurethanes to flow under processing conditions, enabling reshaping and mechanical recycling without significant loss of properties.

Low-temperature pyrolysis as a functionalization tool
A complementary approach uses reduced-temperature pyrolysis to introduce reactive end groups while retaining over 90% of the material as a solid polymer—lowering energy demand and expanding future upcycling options.

Future Outlook

Advancing polyolefin circularity will require scalable, energy-efficient strategies that go beyond mechanical recycling. Melt-processable upcycling routes, dynamic thermosets, and low-temperature functionalization techniques offer promising pathways to convert plastic waste into high-performance, long-lived materials. Continued collaboration between academia, industry, and policy stakeholders will be critical to translating these approaches into real-world solutions that reduce environmental impact while sustaining the benefits plastics provide.

Guest Speaker

Megan Robertson

Neal R. Amundson Professor

William A. Brookshire Department of Chemical and Biomolecular Engineering

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