IRDL, Université Européenne Bretagne, CNRS, UMR 6027, Lorient, France.
IRDL, Université Européenne Bretagne, CNRS, UMR 6027, Lorient, France.
Carbohydr Polym. 2019 Feb 15;206:48-56. doi: 10.1016/j.carbpol.2018.10.065. Epub 2018 Oct 28.
Flax retting is a major bioprocess in the cultivation and extraction cycle of flax fibres. The aim of the present study is to improve the understanding of the evolution of fibre properties and ultrastructure caused by this process at the plant cell wall scale. Initially, investigations of the mechanical performances of the flax cell walls by Atomic Force Microscopy (AFM) in Peak Force mode revealed a significant increase (+33%) in the cell wall indentation modulus with retting time. Two complementary structural studies are presented here, namely using X-Ray Diffraction (XRD) and solid state Nuclear Magnetic Resonance (NMR). An estimation of the cellulose crystallinity index by XRD measurements, confirmed by NMR, shows an increase of 8% in crystallinity with retting mainly due to the disappearance of amorphous polymer. In addition, NMR investigations show a compaction of inaccessible cell wall polymers, combined with an increase in the relaxation times of the C4 carbon. This densification provides a structural explanation for the observed improvement in mechanical performance of the secondary wall of flax fibres during the field retting process.
亚麻沤麻是亚麻纤维种植和提取过程中的一个主要生物处理过程。本研究旨在从植物细胞壁尺度深入了解该过程引起纤维性能和超微结构演变的机制。首先，利用原子力显微镜（AFM）中的峰值力模式对亚麻细胞壁的机械性能进行研究，结果表明随着沤麻时间的增加，细胞壁压痕模量显著增加（+33%）。这里介绍了两项互补的结构研究，即 X 射线衍射（XRD）和固态核磁共振（NMR）。通过 XRD 测量和 NMR 验证，对纤维素结晶度指数的估计表明结晶度增加了 8%，这主要是由于无定形聚合物的消失。此外，NMR 研究表明不可接近细胞壁聚合物的致密化，同时 C4 碳的弛豫时间增加。这种致密化提供了一个结构解释，说明在田间沤麻过程中，次生细胞壁的机械性能得到了提高。
