Biobased sustainable materials made from starch and plasma/ultrasound modified Agave fibers: Structural and water...

This study aims to investigate the effect of green modification methods (ultrasound and plasma treatment) on a by-product of the tequila industry (Agave fibers), which can be useful as raw material to elaborate biodegradable and hydrophobic starch films. FTIR analysis indicated a decrease of hydrophilic lignocellulosic components, since the cavitation and etching effect of ultrasound/plasma treatment reduced the large number of hydroxyl groups of the fibers. The inclusion of ultrasound/plasma modified fibers in the starch matrix limited the starch-glycerol interactions, reducing the free volume of the starch and the binding sites for water. Therefore, the solubility (%S), swelling (%W) and water vapor permeance (WVPe) of the films decreased from 27 to 16%, 57 to 50% and 0.37 to 0.21 g/day m²Pa, respectively. Furthermore, the water contact angle (WCA) and relative crystallinity values increased. The results indicated that the treatments are suitable green technologies to obtain hydrophobic fillers useful to develop sustainable materials.