Modular infusion: A practical application of vitrimers derisking manufacture and enabling repair and (dis)assembly

A well-known challenge in the production of large composite structures using liquid resin infusion processes is the lack of repeatability. Furthermore, when in service damage occurs facilitating effective repairs can be costly so often large composite components are scrapped. These two factors restrict the adoption of composites, and impact on the ongoing sustainability of the use of composite materials in a wide range of sectors. Hence, a robust manufacturing procedure is devised that involves dividing a preform into discrete modular regions using resin barrier films; these allow preferential and predictable flow front propagation. The effectiveness of the procedure is demonstrated on a complex integrated rib structure using X-ray computed tomography (XCT), which showed a significant reduction in void volume in the modular infusion. To address the repairability of composite structures and to ease the assembly of composite parts the barrier films are further functionalised using vitrimer type resins. It is shown that these can enable a novel fusion assembly of sub-components with different break-down options and provide a means of targeted interfacial repair. It is shown that in T-stiffened samples the functionalised modular sample pull-off strength was comparable to a VARTM baseline with excellent restoration of load carrying capabilities after 3 repairing cycles. It is demonstrated that application of a resin film barrier can effectively control manufacturing and reduce the magnitude of voids. Moreover, resin barrier films can be used to create an interface that supports repair and enables reconfigurable modular infused structures. The multifunctional film barrier has the potential to enhance the entire lifecycle of a large and difficult to recycle large composite structure. The multifunctional resin barrier film provides a means of de-risking manufacture, facilitating in-service repair and disassembly at end of life allowing for elements of the structure to be salvaged or more readily recycled.