FOREST validates sustainable composite materials that reduce transport component weight by up to 35%

Reducing vehicle weight is one of the most effective ways to improve transport efficiency and lower emissions. In this context, the EU-funded FOREST project, coordinated by AIMPLAS, the Plastics Technology Centre, has developed and validated advanced lightweight biocomposites for automotive, aerospace and bus applications, achieving weight reductions of up to 35% compared with conventional components while maintaining performance, safety and durability.

The project’s results have demonstrated that it is possible to develop transport components containing more than 50% sustainable materials by combining bio-based feedstocks, recycled carbon fibres and functional additives without compromising performance, safety or industrial feasibility.

The final demonstrators developed in the project achieved 30-35% weight reduction compared with conventional reference components, while meeting mechanical and functional requirements, including fire performance and, where relevant, electromagnetic interference shielding.

Manufacturing efficiency improved alongside material sustainability. Process optimisation delivered a 15-25% reduction in energy consumption compared with conventional methods, driven by accelerated curing chemistry that cut cycle times by 20-40%, one-shot manufacturing concepts that eliminated intermediate processing steps, and the removal of freezer storage requirements. Engineering costs fell by 15-20% through simplified tooling, fewer mould iterations, and increased process robustness.

“FOREST demonstrates that sustainability, lightweighting and safety are not competing objectives. By integrating bio-based chemistry, recycled carbon fibres and multifunctional performance, we are reshaping advanced composites for the future of mobility,” said Fernando Ramos, FOREST Project Coordinator at AIMPLAS.

Three Demonstrators as Real-World Proof

To demonstrate the industrial feasibility of the developed materials and manufacturing processes, FOREST designed, manufactured and validated three demonstrators addressing key challenges in automotive, aerospace and public transport applications:

Electric vehicle battery cover: A thermoset compression-moulded enclosure using a bio-benzoxazine matrix with recycled carbon fibre reinforcement and bio-based flame-retardant and EMI-shielding additives, validated for structural performance, fire resistance and electromagnetic shielding.

Aeronautic cockpit ceiling panel: A lightweight thermoplastic composite solution using recycled carbon fibre organosheet reinforcement and Bio-PA overmoulding, replacing conventional phenolic-resin panels with improved sustainability and equivalent aerospace performance.

Bus roof pultrusion profile: Continuous structural profiles produced by combining recycled carbon fibre yarn with Bio-PA via thermoplastic pultrusion, a scalable and automated route to high-performance bus roof components.

Three Bio-Based Resin Systems Validated at Pilot Scale

Supporting the development of these demonstrators was another major milestone of the project: the pilot-scale development, optimisation and validation of three bio-based resin systems tailored to the specific requirements of different transport applications. The three systems, a bioacrylic resin, a biobenzoxazine resin and a biopolyamide 6, met the requirements for integration into the final demonstrators, demonstrating progress in bio-based content, processability and multifunctional performance.

The bioacrylic resin system based on Elium achieved stable formulations with about 25% bio-based content while maintaining recyclability, processability, and thermomechanical performance. Its integration with recycled carbon fibre was demonstrated using C-RTM and organosheet processing.

The biobenzoxazine resin system reached approximately 85-87% renewable carbon, with catalyst selection and post-curing improving curing, thermal stability, and mechanical properties, enabling use in SMC compression moulding for automotive applications.

The biopolyamide 6 system was developed in partial and full bio-based versions. FOREST showed polymerisation feasibility and scale-up, optimising formulations for viscosity, fibre impregnation, and compatibility with pultrusion and overmoulding processes.

Closing the Loop on Carbon Fibre

Alongside increasing the use of bio-based materials, the project has also focused on the valorisation of carbon fibre waste to support more circular solutions for the transport sector.

Carbon fibre is one of the most energy-intensive materials used in transport. FOREST targeted the recovery of up to 100% of carbon fibre waste, converting it into high-quality semi-finished materials for new applications. The project confirmed that properly recovered fibres retain a high proportion of their original mechanical performance, a critical finding for circular composite value chains.

The project’s results were supported by extensive testing. This followed a staged characterisation approach covering resin rheology, curing behaviour and thermal analysis, tensile, flexural and impact testing, fire behaviour, microscopy and EMI-shielding evaluation. This testing-driven development approach ensured that sustainability improvements did not create hidden weaknesses in structural integrity, fire performance or manufacturing robustness.

As FOREST concludes, the project provides a clear example of how European research and innovation can help the transport industry reduce weight, cut process energy demand, increase sustainable material content and valorise carbon fibre waste. Its demonstrators show that circular, lightweight and safe composite solutions are no longer only laboratory concepts, but validated prototypes with a pathway towards industrial uptake.