Enzyme‐treated Tunisian Alfa fibers reinforced polylactic acid composites: An investigation in morphological, thermal, mechanical, and water resistance properties.

The present work is a comparative study of the impact of different Alfa fiber modifications on fiber properties, as well as on polylactic acid (PLA) composites behaviors. A specific process that combines successively mechanical, chemical, and enzymatic treatments (xylanase and pectinase) was employed to optimize the performances of Alfa fibers. The treatments reduced the levels of lignin, hemicellulose, and pectin in the fibers. This reduction was associated with a rise of defibrillation degree, an increase of cellulose content and an enhancement of thermal stability, as shown with SEM observations, biochemical composition determination, FTIR measurements and thermo‐gravimetric analyzer results. Bio‐composites were fabricated using a twin‐screw extruder and an injection‐molding machine with a fiber load of 20%. Tensile, flexural and water absorption tests revealed an improvement of mechanical strengths and water resistance for the treated fibers composites, with the enzyme treatment being the most efficient. SEM analysis showed a better impregnation and distribution of enzyme treated fibers within the matrix. An improvement of the thermal properties of composites filled with Alfa treated fibers was noticed when compared with untreated fibers composites. The data indicated that the technology of enzymes can be used as a powerful and eco‐friendly approach to treat natural fibers and to increase their potential of reinforcement. [ABSTRACT FROM AUTHOR]