Analysis of morphological changes leading to the enhancement of tensile properties of yarns from Manila hemp fiber

We studied the morphology of yarns obtained from Manila hemp (also known as Abacá) fiber bundles to find a possible correlation with the enhancement in mechanical properties of yarns relative to the original natural fiber bundle. Long Manila hemp fiber bundles had lignin and hemicelluloses removed, twisted and dried to form yarns. Scanning electron micrography revealed that the collapse of lumens inside the fibers leads to densification and consequent increase of tensile properties of the yarns. The densification occurs after the chemical removal of noncellulosic substances from the interstices of cellulose fibrils. These cellulosic elements are then bridged by hydrogen bonds during the drying step of yarn fabrication.