El Hage Roland, Carvalho Martins Raíssa, Brendlé Clément, Lafon-Pham Dominique, Sonnier Rodolphe
PCH, IMT Mines Alès, 6 Avenue de Clavières, 30100 Alès, France.
EuroMov Digital Health in Motion, University Montpellier, IMT Mines Ales, 6 Avenue de Clavières, CEDEX, 30319 Alès, France.
Molecules. 2024 Aug 21;29(16):3945. doi: 10.3390/molecules29163945.
The accelerated weathering of flax and miscanthus fibers possessing distinct chemical compositions was investigated. The chosen fibers included raw, extractive-free (EF) and delignified samples (x3), alone and used as fillers in a stabilized polypropylene blue matrix (PP). Modifications in both color and the chemical composition of the fibers throughout the weathering process under ultraviolet (UV) light were meticulously tracked and analyzed by spectrophotometry and attenuated total reflectance with Fourier-transform infrared spectroscopy (ATR-FTIR). The inherent nature and composition of the selected fibers led to varied color-change tendencies. Raw and EF flax fibers exhibited lightening effects, while raw and EF miscanthus fibers demonstrated darkening effects. Extractives exhibited negligible influence on the color alteration of both flax and miscanthus fibers. This disparity between the fibers correlates with their respective lignin content and type, and the significant formation of carbonyl (C=O) groups in miscanthus. Better stability was noted for delignified flax fibers. A comparative study was achieved by weathering the PP matrix containing these various fibers. Contrary to the weathering observations on individual fibers, it was noted that composites containing raw and EF flax fibers exhibited significant color degradation. The other fiber-containing formulations showed enhanced color stability when compared to the pure PP matrix. The study highlights that the UV stability of composites depends on their thermal history. As confirmed by thermogravimetric analysis (TGA), fiber degradation during extrusion may affect UV stability, a factor that is not apparent when fibers alone are subjected to UV aging.
研究了具有不同化学成分的亚麻和芒草纤维的加速老化情况。所选纤维包括原始纤维、无提取物（EF）纤维和脱木质素样品（x3），这些纤维单独使用或用作稳定聚丙烯蓝色基体（PP）中的填料。在紫外（UV）光下的老化过程中，通过分光光度法和傅里叶变换红外光谱衰减全反射法（ATR-FTIR），对纤维的颜色和化学成分变化进行了细致跟踪和分析。所选纤维的固有性质和成分导致了不同的颜色变化趋势。原始和EF亚麻纤维呈现出变浅的效果，而原始和EF芒草纤维则呈现出变深的效果。提取物对亚麻和芒草纤维的颜色变化影响可忽略不计。纤维之间的这种差异与其各自的木质素含量和类型有关，以及芒草中羰基（C=O）基团的大量形成。脱木质素亚麻纤维的稳定性更好。通过对含有这些不同纤维的PP基体进行老化，开展了一项对比研究。与对单个纤维的老化观察结果相反，发现含有原始和EF亚麻纤维的复合材料出现了明显的颜色降解。与纯PP基体相比，其他含纤维配方显示出更高的颜色稳定性。该研究强调，复合材料的UV稳定性取决于其热历史。热重分析（TGA）证实，挤出过程中的纤维降解可能会影响UV稳定性，而单独对纤维进行UV老化时，这一因素并不明显。
