Commercial Scale Methods for Reclamation and Reuse of Carbon Fiber

RT&L FOCUS AREA(S): General Warfighting Requirements TECHNOLOGY AREA(S): Air Platforms; Materials / Processes OBJECTIVE: Design and develop methodologies to reclaim and reuse carbon fiber from in-process waste and scrap parts generated in the manufacturing of advanced aircraft, and from end-of-life aircraft. DESCRIPTION: Manufacturing waste (pre-impregnated edge trimmings, trimmed cured composites, etc.) and scrap, generated during the manufacturing of advanced composite parts for aircraft and rotorcraft, is currently landfilled. This situation arises because there are no commercial methods to reclaim the fiber from these composites. Additionally, as current aircraft reach the end of service, they need to be deconstructed and recycled, by as high a degree as possible, rather than landfilled. Robust, commercial scale methods are sought for reclaiming carbon fiber from end-of-life parts, in-process excess materials, and scrap. The scrap generated during advanced composite manufacturing consists largely of aerospace-grade carbon fiber and advanced thermoset resins, including epoxies and bismaleimides (BMI). Other materials may also be present, including but not limited to, fiberglass and aramid fibers, metallic fasteners, wires, and mesh. Any process proposed under this STTR topic must be capable of handling these non-ideal sources of carbon fiber [Refs 1, 5]. Any approach proposing to process the composites' waste, scrap parts, and end-of-life parts must be cost-effective and follow all appropriate environmental regulations. Business case analysis should include, but not be limited to, data such as cost, energy input, and CO2 emission, as compared to current composite usage and disposal methods. Once the carbon fiber is recovered from the composite waste and parts, it must be converted into raw material that would be of interest to the Navy and to non-military customers such as commercial aircraft, automotive, or sporting goods industries. Recovered carbon fibers can be continuous or discontinuous. Prototype demonstration of viable, large scale, composite forming processes is desired. Although not required, it is highly recommended to work in coordination with the original equipment manufacturer (OEM) to ensure proper design and to facilitate transition of the final technology. It is also recommended that awardees to work directly with aircraft fabricators to determine the potential types and amounts of scrap and in-process excess materials to be processed. PHASE I: Define and develop a pilot scale approach to reclaim carbon fiber from carbon fiber reinforced composites that is directly scalable to commercial practice. Candidate approaches should include processes for the deconstruction of waste and scrap composite materials, and for recovery and separation of fiber from the polymer matrix. The use of reclaimed fiber in making composite test parts should use multiple fabrication methods, and mechanical properties obtained from parts fabricated using the recycled material should be comparable to parts fabricated using its original non-recycled materials [Ref 2]. Data comparison of the developed recycling method to traditional composite waste disposal from a financial as well as an environmental prospective should be included. The Phase I effort will include any prototype plans to be developed under Phase II. PHASE II: Demonstrate the methodology to reclaim and reuse carbon fiber from in-process waste and scrap with data to include, but not be limited to, cost, energy input, and CO2 emissions versus current composite usage and disposal methods. Define and validate a process evaluation, process modeling, and process economics for the selected approach. PHASE III DUAL USE APPLICATIONS: Finalize and mature the technology for transition and insertion into aircraft component fabricators and end-of-life aircraft processors. The technology developed under this STTR effort has direct applicability to the commercial aircraft industry. Other applications for this method may include the automotive industry. Remaining fibers that cannot be used in either aircraft or automotive may benefit sporting goods manufacturers. REFERENCES: Jiang, G.; Pickering, S.J;, Lester, E.; Blood, P. and Warrior, N. Recycling carbon fibre/epoxy resin composites using supercritical propanol. 16th International Conference on Composite Materials, Kyoto, Japan, July 8-13 2007. http://www.iccm-central.org/Proceedings/ICCM16proceedings/contents/pdf/FriF/FrFA2-03ge_pickerings225687.pdf Liu, Y.; Liu, J.; Jiang, Z. and Tang, T. Chemical recycling of carbon fibre reinforced epoxy resin composites in subcritical water: Synergistic effect of phenol and KOH on the decomposition efficiency. Polymer Degradation and Stability, 97(3), March 2012, pp. 214 220. https://doi.org/10.1016/j.polymdegradstab.2011.12.028 Liu, Y.; Meng, L.; Huang, Y. and Du, J. Recycling of carbon/epoxy composites. Journal of Applied Polymer Science, 94(5), December 2004, pp. 1912-1916. https://www.researchgate.net/publication/230214736_Recycling_of_carbonepoxy_compositesb McConnell, V.P. Launching the carbon fibre recycling industry. Reinforced Plastics, 54(2), March 29, 2010, pp. 33-37. http://www.reinforcedplastics.com/view/8116/launching-the-carbon-fibre-recycling-industry/ Pickering, S.J. Recycling technologies for thermoset composite materials current status. Composites Part A: Applied Science and Manufacturing, 37(8), August 8, 2006, pp. 1206-1215. https://doi.org/10.1016/j.compositesa.2005.05.030