Résumé
The accelerated weathering of flax and miscanthus fibers possessing distinct chemicalcompositions was investigated. The chosen fibers included raw, extractive-free (EF) and delignifiedsamples (x3), alone and used as fillers in a stabilized polypropylene blue matrix (PP). Modificationsin both color and the chemical composition of the fibers throughout the weathering process underultraviolet (UV) light were meticulously tracked and analyzed by spectrophotometry and attenuatedtotal reflectance with Fourier-transform infrared spectroscopy (ATR-FTIR). The inherent natureand composition of the selected fibers led to varied color-change tendencies. Raw and EF flaxfibers exhibited lightening effects, while raw and EF miscanthus fibers demonstrated darkeningeffects. Extractives exhibited negligible influence on the color alteration of both flax and miscanthusfibers. This disparity between the fibers correlates with their respective lignin content and type, andthe significant formation of carbonyl (C=O) groups in miscanthus. Better stability was noted fordelignified flax fibers. A comparative study was achieved by weathering the PP matrix containingthese various fibers. Contrary to the weathering observations on individual fibers, it was noted thatcomposites containing raw and EF flax fibers exhibited significant color degradation. The other fibercontaining formulations showed enhanced color stability when compared to the pure PP matrix. Thestudy highlights that the UV stability of composites depends on their thermal history. As confirmedby thermogravimetric analysis (TGA), fiber degradation during extrusion may affect UV stability, afactor that is not apparent when fibers alone are subjected to UV aging.