Composite materials display many advantages over traditional materials, whether in terms of lightness or mechanical and chemical resistance. In a context of sustainable development, a growing number of works relate to the production of composites with bio-based matrices including polylactide (PLA), which has become a major actor in the market which could in the long term serve as an alternative to petroleum-based polyolefins.[1] Among the various composites production processes, Resin Transfer Molding (RTM) is a specific process which relies on the injection, into a mold containing fibers, of a monomer and a catalyst in order to carry out the polymerization of the matrix in situ. The major advantage over conventional melt processes is the possibility of reaching a high amount of fibers while improving their wetting by the matrix. While a wide selection of thermosetting matrix resins are available on the market for RTM process, there are only a few commercial resins for thermoplastic matrices.[2] Although work has been carried out in RTM with e-caprolactone,[2] composites with a PLA matrix via this process had never been described. Recent work carried out at UMET made it possible to obtain the first prototypes of PLLA/glass fiber composites.[3a] We present here current work aimed at strengthening the mechanical properties of the PLLA matrix by producing a novel family of composites by copolymerization of L-LA with other cyclic esters.[3b] [1] M. Jamshidian, E. A. Tehrany, M. Imran, M. Jacquot, S. Desobry, Compr. Rev. Food. Sci. F., 2010, 9, 552-571. [2] B. Campos, S. Bourbigot, G. Fontaine, F. Bonnet, Polym. Compos. 2022, 43, 2485-2506 [3] (a) E. Louisy, F. Samyn, S. Bourbigot, G. Fontaine, F. Bonnet. Polymers, 2019, 11, 339-347. (b) B. Miranda Campos, G. Fontaine, S. Bourbigot, G. Stoclet, F. Bonnet. ACS Appl. Polym. Mater, 2022, 4, 6797-6802.