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Cornell University Innovates Recyclable Thermoset Plastics

Researchers at Cornell University have made a significant breakthrough in the development of a recyclable substitute for a type of durable plastic known as thermosets. These plastics are commonly utilized in various applications, ranging from automotive tires to medical implants like replacement hip joints, as well as in recreational items such as bowling balls.

Thermosets are characterized by their “crosslinked polymer” chemical structure, which provides remarkable longevity and resilience. However, this durability comes at a cost, rendering traditional thermoset materials, which account for 15%-20% of global polymer production, impossible to recycle. As a result, these materials are predominantly incinerated or disposed of in landfills, with no current mechanisms for recycling.

“At present, absolutely none of the world’s thermoset materials are recycled,” stated Brett Fors, who heads the chemistry and chemical biology department at Cornell. This situation highlights a critical environmental issue that the Fors lab aims to address.

The researchers have introduced an alternative solution featuring a bio-sourced formulation that mirrors the durability and versatility of traditional thermosets, while also being easily recyclable and environmentally degradable. This innovative approach aligns with growing sustainability efforts in materials science.

“Our methodology—spanning creation to reuse—is significantly more sustainable compared to existing materials,” explained Reagan Dreiling, a PhD candidate and lead author of the study published in Nature.

The study focuses on dihydrofuran (DHF), a chemical building block derived from biological sources that holds promise for competing with conventional petroleum-based materials.
Dreiling employed DHF as a foundational monomer in a two-step polymerization process, yielding a crosslinked polymer that can not only be recycled through heat but is also capable of natural degradation in the environment.

The new DHF thermosets exhibit properties on par with established commercial thermosets, such as high-density polyurethane—which finds applications in electronics, packaging, and footwear—and ethylene propylene rubber, used extensively in garden hoses and automotive components.

This new material presents an advancement over conventional petrochemical thermosets by fostering a circular economy model, as Fors highlights. The DHF-based polymers can be recycled back into their monomeric form, enabling their reuse from the ground up. Furthermore, in instances where the material enters the environment unintentionally, it is designed to break down into harmless components over time.

The research team is currently pursuing practical applications for this innovative DHF-based material, with an emphasis on making it suitable for 3D printing. Additionally, they are experimenting with other monomers to diversify the material’s properties.

“For over a century, our efforts have focused on creating polymers designed to last indefinitely. We are now shifting our perspective to develop materials that are not permanent but can decompose safely within the environment,” noted Fors.

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