CANNON has developed a revolutionary approach to recycling polyurethane (PU) and PU-glass fiber composites (GFRPs).

The project, named POSSIBLE, for “PrOduce SuStainabLE Industrial Bodies”, has laid the groundwork for PU and GFRPs end-of-life recycling and reuse, successfully demonstrating that ground foam and granulated parts can be used as secondary reinforcement materials in new composite formulations.

The approach is developed in close cooperation with PU processor MAP S.p.A. and the University of Bergamo, with co-funding from the Italian strategic plan for the EU recovery fund NextGenerationEU.

CANNON will present this innovative recycling approach at JEC World 2026 on March 10-12 at Paris Nord Villepinte.

Previous challenge: Slow and expensive

Scientific research has developed several potential chemical recycling routes for thermosets, but these work are on a laboratory scale and are often too slow, too expensive, or incompatible with existing PU manufacturing processes.

CANNON therefore decided to focus on a more direct approach, reintegrating pure or composite rigid PU waste through two complementary methods, both compatible with their high-pressure systems.

First approach: Transforming into micrometric powders

The first approach involved transforming rigid foam waste into micrometric powders, which were then dispersed into the polyol to form a slurry and dosed as a liquid component using a mixing head.

Rigid foam waste is transformed into two types of powder, a fine powder (PU-A), with most particles below 75 µm, and a coarser powder (PU-B), between 300 and 500 µm. The dispersions were made by introducing the dried powders into a reactor with polyol, up to 20% by weight of the polyol stream, equal to about 5% of the foam.

To handle these dense slurries, CANNON divided the isocyanate and the polyol into two streams, one “clean” and one “loaded.” This way, the mixing energy remains high, and the system remains stable, even with viscosities that can exceed 10,000 mPa·s.

Then, the slurry is dosed via a scraper cylinder. Subsequent analyses show homogeneous panels with good distribution for the recycled powder. Furthermore, the thermal conductivity increases by only about 4% compared to the reference, which allows for maintaining valid insulating performance even with 3% recycled content in the foam.

Second approach: Introducing as solid filler into mixture

The second involved using rigid PU granulate and polyurethane-glass fiber composite, introduced as a solid filler into the mixture using dedicated dosing systems combined with the FPL 36 IW mixing head for Interwet-LFI (Long Fiber Injection) technology patented by CANNON.

CANNON FPL 36 IW high-pressure mixing head.

PU waste, including polyurethane-glass fiber composites, is transformed into granules. These are then dosed as a solid filler directly into the Interwet-LFI head. This technology is already in use to combine polyurethane and shredded glass fiber and allows recycled granules to be integrated into the mixing flow.

To determine the most efficient feeding system, both pneumatic fluid bed transport and a flexible screw conveyor were tested. The former offers good results with dense, regular granules, but becomes unstable with light or powdery materials.

The flexible screw conveyor proved to be more versatile: it allows flow rates from a few grams to over 100 g/s, without pulsations or bridging, making it ideal for GFRP granules from waste. With this configuration, panels containing up to 40% recycled granules by weight were produced, with uniform distribution throughout the thickness.

True circularity in thermosets, and going beyond

Subsequent testing by CANNON showed that recycling rigid polyurethanes and GFRP composites can become an integral part of production lines. They do not require invasive processes or radical changes to formulations but transform waste into a material that can be reused in the process, with immediate economic and environmental benefits.

This is a concrete step towards circularity in thermosets, a family of materials for which recycling was previously considered almost impossible.

Based on research conducted during POSSIBLE, CANNON is now working on commercially viable solutions for recycling PU and GFRPs that will enter the market in the near future.