https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Mon, 13 Apr 2026 23:25:58 GMT 2026-04-13T23:25:58Z http://hdl.handle.net/10985/27084 Development of a custom commingled flax/PLA wrapped yarn for additive manufacturing of long-fibre biocomposites QUEREILHAC, Delphine; CAILLAULT, Thomas, Raphaël; TEREKHINA, Svetlana; BAR, Mahadev; MOREL, Guillaume; FAZZINI, Marina; ABIDA, Marwa; DE LUYCKER, Emmanuel; OUAGNE, Pierre Plant fibres are promising reinforcements for bio-composites in additive manufacturing, but their use as long fibres remains limited, often reduced to short particles that underuse their potential. This study presents a customised yarn design that not only maintains fibre alignment parallel to the yarn axis but also ensures core resin impregnation. Commingling and wrap spinning techniques were used to produce four flax/PLA yarns with varying compositions. The manufacturing process and printing of unidirectional composite specimens are detailed. Tomography revealed up to 3.3 times lower intra-yarn porosity thanks to commingling, and tensile tests showed a modulus increase by a factor of 2.1 compared to similar previous works using conventional twisted yarns. These results pave the way for broader use of long flax fibres in 3D printing. Mon, 25 Aug 2025 00:00:00 GMT http://hdl.handle.net/10985/27084 2025-08-25T00:00:00Z QUEREILHAC, Delphine CAILLAULT, Thomas, Raphaël TEREKHINA, Svetlana BAR, Mahadev MOREL, Guillaume FAZZINI, Marina ABIDA, Marwa DE LUYCKER, Emmanuel OUAGNE, Pierre Plant fibres are promising reinforcements for bio-composites in additive manufacturing, but their use as long fibres remains limited, often reduced to short particles that underuse their potential. This study presents a customised yarn design that not only maintains fibre alignment parallel to the yarn axis but also ensures core resin impregnation. Commingling and wrap spinning techniques were used to produce four flax/PLA yarns with varying compositions. The manufacturing process and printing of unidirectional composite specimens are detailed. Tomography revealed up to 3.3 times lower intra-yarn porosity thanks to commingling, and tensile tests showed a modulus increase by a factor of 2.1 compared to similar previous works using conventional twisted yarns. These results pave the way for broader use of long flax fibres in 3D printing.