Surface lignin removal on coir fibers by plasma treatment for improved adhesion in thermoplastic starch composites.

The high lignin to cellulose ratio of coir fibers results in low compatibility between these fibers and natural polymers like starch, leading to poor mechanical properties in the composites. Plasma treatment using either air or oxygen proved to be an effective in removing the lignin rich amorphous layer on coir fibers, as it was clearly observed by SEM. The ratio of the FTIR signal related to lignin (1508cm) and cellulose (1317cm) decreases 10 times for air plasma treated fibers and 20 times for oxygen plasma treated samples.