Thermoset CFRP cannot be melted or remolded once cured, and much of it ends up incinerated or landfilled at end of life. GHG-reduction and circularity requirements are tightening across aircraft, automotive and industrial applications. That limitation has kept damaged parts on a replace-rather-than-repair path.
Teijin Limited has developed a new thermosetting, long carbon fiber-reinforced plastic (CFRP) that combines heat-activated self-healing with chemical recyclability. It matches the mechanical properties of conventional CFRP.
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Extends product lifetime and reduces resource consumption
The new CFRP addresses two limitations of conventional thermoset composites at once: damage tolerance and end-of-life recovery. Damaged areas of the resin layer can be repaired by heating rather than discarding the part, extending product lifetime and reducing resource consumption.
Additionally, the material can be recycled through a chemical decomposition process that recovers the long carbon fibers for reuse. This supports circularity goals without sacrificing the strength and light weight that make CFRP suitable for structural applications. In short: a thermoset CFRP repairable by heat instead of scrapped, and recyclable by chemical decomposition instead of high-temperature incineration. It does this without giving up the mechanical performance of conventional CFRP.
Three mechanisms behind the self-healing, remoldable resin
Three mechanisms make this possible: heat-triggered self-healing, heat-triggered remolding, and chemical decomposition for carbon fiber recovery.
- Self-healing: a damaged resin layer can be repaired by heating it for a short time at a specified temperature.
- Remolding: the resin becomes flowable when reheated within a specified temperature range, enabling compression remolding.
- Fiber recovery: the resin is decomposed by soaking it in a specific chemical solution, replacing high-temperature combustion.
According to Teijin, a damaged resin layer can be repaired by heating it for a short time at a specified temperature. This allows the material to stay in service rather than being scrapped.
Conventional thermoset CFRP cannot be remolded because the cured resin does not melt or flow under heat. Teijin’s new resin, by contrast, becomes flowable when heated within a specified temperature range. The company reports this makes compression remolding and other reprocessing methods possible.
Recovering carbon fiber from conventional thermoset CFRP typically requires burning off the resin in a furnace above 400°C over an extended period. Teijin describes this method as energy-intensive and environmentally burdensome. The company’s new resin can instead be decomposed by soaking the material in a specific chemical solution. This separates the long carbon fibers from the resin without combustion.
This resin builds on Teijin’s broader effort to reduce GHG emissions and cut waste. That includes its Tenax Next brand of carbon fiber, made from circular feedstocks.