Hybrid effects in biobased benzoxazine vitrimer composites reinforced with flax and carbon fibres

Authors

BOURDON K., BOULIC V., ABDALLAH BOINA D., VERGE P., SCHMIDT D.F., HUBER T.

Reference

Materials and Design, vol. 258, art. no. 114532, 2025

Description

Fibre-reinforced vitrimers are an emerging class of recyclable composites, but the influence of fibre type and stacking sequence on performance remains underexplored. This study examines benzoxazine vitrimer composites with flax and/or carbon fibres, focusing on flexural strength, interlaminar shear strength (ILSS), and healing efficiency (property recovery after damage and reprocessing). Composites were fabricated using vacuum-assisted compression resin transfer moulding, with morphology analysed via X-ray microtomography. Among hybrid configurations, sandwich structures with carbon fibre skins showed higher flexural strength (up to 580 ± 50 MPa) compared to those with carbon fibre cores (180 ± 6 MPa). Increasing flax content reduced both flexural strength (from 580 ± 50 MPa to 500 ± 7 MPa) and ILSS (from 27.5 ± 0.7 MPa to 18.4 ± 1.5 MPa) for similar sandwich structures. Alternating structures exhibited intermediate performance, lower than composites with carbon fibre skins but higher than composites with flax fibre skins. Significantly higher flexural strength and modulus recovery was observed in composites with flax fibre skins (>87 %) vs. carbon fibre skins (<45 %), while ILSS recovery ranged from 78 % to 90 % regardless of structure. These findings highlight the role of stacking sequence and fibre selection in optimising the damage-repair performance of vitrimer composites.

Link

doi:10.1016/j.matdes.2025.114532