Experimental study on a new generation of recycled composite laminates

• Assembling uncured patches of scrap prepreg is a sustainable way of producing laminates with still relevant mechanical properties and recover useful material. • The way the patched laminate is assembled affects stiffness rather than strength of the new laminate. • Patch size and aspect ratio have negligible effect within the investigated range while a partial overlap between patches brings higher mechanical properties. • Fracture mode, under investigated bending stress, is dominated by fiber breakage rather than delamination. Composite manufacturing processes generate a significant amount of waste due to the raw material being supplied in sheet form and cut-outs. The unused scraps of prepreg are typically discarded, leading to the disposal of up to 35 % of the purchased material, accompanied by economic losses and negative environmental impacts. The authors propose collecting these scraps, cutting them into smaller, regular patches, and assembling them into a new, patched prepreg sheet. This study presents an experimental investigation into the mechanical properties of such patched material, assembled using two different architectures and three patch geometries. Five different configurations are designed, manufactured, and tested, with results compared to samples made from the original unpatched material through four-point bending tests. When patches are assembled in a regular geometry, the new material possesses around 50 % and 90 % of the original strength and stiffness, respectively, demonstrating potential for use in load-bearing applications. The methods of assembling the patches following a regular pattern also resulted in significantly better properties than a random deposition, which despite its lower cost to implement does not retain relevant mechanical characteristics. Of the two arranged investigated architectures, the one being more complex to manufacture shows 9 % and 5 % higher stiffness and strength, respectively, than the simpler one. Fracture analysis shows that failure mainly takes place in between of a patch, rather than the superposition areas.