Metaplexis japonica seed hair fiber: a member of natural hollow fibers and its characterization

Metaplexis japonica seed hair fibers (Mj-fiber), harvested from the seed pods of Metaplexis japonica (Apocynaceae: Asclepiadoideae) originating in China, Japan and Korea, have features ensuring its potential application in the textile and other industrial fields. In spite of the extensive study on the medicinal properties of Metaplexis japonica, research literature about Mj-fiber is quite limited. We obtained Mj-fibers by artificial peeling and seed removing; then the fiber morphology, chemical composition, structures, fiber surface absorption characteristics, and tensile and thermal properties were studied in detail. From the results, Mj-fiber has a hollow structure with a thin fiber wall and large lumen, in which the hollowness is over 92%. Uniquely, Mj-fiber is a natural profiled fiber with a cross-section of a "cross flower" morphology. At the same time, the density of it is very low, accounting for only one-fifth of the cotton fibers, and the fiber length distribution is relatively concentrated. The main component is cellulose, with a content of 53.9 ± 3.20% and structure of cellulose I. In particular, Mj-fiber has excellent hydrophobic and oil affinity surface characteristics. Moreover, the fibers bulkiness and warmth retention performance are comparable to that of duck down. Therefore, the results provide an experimental basis for the application of Mj-fibers in the textile and other industrial fields.