Open Access

ARTICLE

The Mechanical and Crystallographic Evolution of Stipatenacissima Leaves During In-Soil Biodegradation

Zakia Khelifi^1,2, Mohammed Amine Allal², Nabil Abou-bekr², Saïd Taïbi¹, Benoît Duchemin^1*

1 Normandy University, ULH, CNRS, LOMC, 76600 Le Havre, France
2 University of Tlemcen, Lab-EOLE, BP 230, 13000 Tlemcen, Algeria

*Corresponding author:

Journal of Renewable Materials 2018, 6(3), 336-346. https://doi.org/10.7569/JRM.2018.634102

Abstract

The in-soil biodegradation of Stipa tenacissima (alfa) leaves was examined. Non-linear mechanical testing was performed at various biodegradation stages. Tensile strength, loading and unloading Young's moduli and dissipation energy decreased with the burial time, whereas plasticity increased. Field-emission scanning electron microscopy (FE-SEM) showed that the fracture cracks propagated in the longitudinal direction in the raw material, resulting in a fracture mode consisting of a mixture of middle lamella delamination and fiber pull-out. In contrast, the cracks were perpendicular to the stem axis in the biodegraded material, demonstrating an important strength loss of the load-bearing fibers. This strength loss was correlated with rapid cellulose degradation. A novel X-ray diffraction (XRD) model was implemented in order to take into account anisotropic size broadening. For the first time, XRD demonstrated the action of biodegradation on unrefined plant tissues under quasi in-situ conditions. Biodegradation induced a progressive loss of crystalline cellulose accompanied with anisotropic crystallite thinning.

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Keywords

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