Enhancement of Tensile Properties of Flax Filaments through Mercerization under Sustained Tension

In the present paper, the tensile properties of flax filaments were modified through mercerization under sustained tension forces. The tensile stress-strain curves of the treated filaments exhibit two stages. The slope of the first stage is much higher than the second one. The mercerization under sustained forces leads the two-stage characteristic to be more obvious. The effect of the sustained tension force on the tensile properties of filaments is dependent on the alkaline concentration. The tensile properties were only remarkably enhanced with high concentration of alkaline (e.g., > 10%) and sustained forces. Compared to the untreated filaments, the maximum tensile strength and modulus with optimum treatment conditions are improved by about 36% and 64% respectively. SEM and X-ray diffraction (XRD) analysis suggested that the enhancement of the tensile properties of the treated flax filaments comes from the orientation of amorphous cellulose molecular chains of micro fibrils and remove of the defects of the filament surfaces.