This thesis aims at valorizing herbaceous plant called Alfa (Stipa tenacissima) in added value application. This raw material is very abundant in Tunisia. Thus, the main idea of this work is to use Alfa fibers as reinforcing elements in bio-composites.
The literature review revealed that this plant has not been extensively studied, which motivated undertaking a comprehensive study of these fibers. A systematic and deep study of the chemical composition, the morphological properties, the electrical charges, the refining kinetics of pulp as well as the physical properties of the paper produced from these fibers was performed and gave several rational insights on Alfa fibers in the context of papermaking.
The second part of this work was devoted to the use of Alfa fibers, as reinforcing fiber mat in composite materials based on biodegradable polymer matrices. In this context, an impregnation technique of the paper films in solutions of two biodegradable polymers – polycaprolactone (PCL) and poly-L-lactide (PLLA) – was chosen. The structural, morphological, thermal and mechanical properties of these new composites were analyzed and discussed.
In addition, an original microwave-assisted grafting of surface chemical modification of Alfa fibers was proposed. In this context, stearic acid was used as a coupling agent. Finally, the effect of the surface modification of the reinforcement on composites properties was assessed and analyzed.