Effect of chemical treatment on the physical and mechanical properties of flax fibers: A comparative assessment

In the present study, flax fibers sorted in two batches were considered for treatment. Set one fibers were treated with chemical reagents - KMnO₄and acetone for durations of 10, 20 and 30min respectively. The second batch of fibers was treated with stearic acid in ethanol for durations of 24h and 36h. Physical properties namely diameter and density were determined. The treated fibers were also tested to determine their tensile and interfacial adhesion strength. A comparison was drawn between untreated fibers and fibers treated with different treating media. A decrement in the diameter of the fibers with increasing duration of treatment was observed. Density increased marginally with treatment due to removal of lighter constituents of the flax fiber like hemicellulose and pectin. Treatment had a positive influence on the tensile and interfacial adhesion strengths of the fibers. However, treatment with stearic acid yielded superior values of mechanical properties in comparison to KMnO₄. The tensile strength values were 54% higher for stearic acid, compared to that for KMnO₄treatment. Higher strength of about 14% was also noted in case of single fiber pull out test with stearic acid treatment. Scanning Electron Microscopy was used to study the changes on the fiber surface due to treatment. Micrographs revealed reduction in grooves with increased duration of chemical treatment, exhibiting a uniformity along the fiber surface by reducing the variation of the fiber diameter along its length. Due to higher mechanical properties, stearic acid treatment was considered to be the superior method for processing the flax fibers.