Physico-mechanical characteristics of bast fibres of Sesamum indicum and Sesamum radiatum for bioprospecting

Natural fibres are renewable, inexpensive and biodegradable sources of sustainable materials from plants or animals. Bast fibres, as the notable natural fibres, are gathered from the outer cell layers of the stem of plant. Mature and young bast fibres from two species of Sesamum, namely Sesamum indicum L. and S. radiatum Schumach. & Thonn. were extracted through traditional water retting technique and analyzed for their physical, mechanical and chemical attributes. Anatomical studies revealed polygon shaped phloem (bast fibre) cells with small lumen were similar to jute, in terms of architecture, and bagasse, in terms of lumen size. Upon extraction and subsequent drying, the young stems of S. radiatum were found to yield more bast fibres by mass compared with the rest of the Sesamum samples, that was, 0.59 g (dry weight) of bast fibres from 100 g (fresh weight) of stem. According to stereo microscopic images, the mature S. radiatum fibres had rougher edges than the rest. Both S. indicum and S. radiatum fibre surfaces also seemed to have pores, according to scanning electron microscopy (SEM) images. The porosity appeared to get more pronounced as the plants got older. The Sesamum bast fibres were also found to be extremely hydrophilic with a high-water retention value. The fibres obtained from S. radiatum were determined to be suitable for the textile industry due to their light colour, ideal diameter and length, and water-holding capacity that matched the requirements of fabric manufacturing. Even in the absence of a mordant, the mature fibres showed a significant degree and evenness of Alizarin dye attachment, which might be correlated to the increase in fibre surface roughness with fibre maturity. These fibres were also discovered to be comparable with jute in terms of phloem cell shape (polygonal), diameter (13–15 m), tenacity (12.86–32.54 gf/(g·km^–1)), and linear density (2.5–3.3 g/km). It suggested that they might find industrial applications if further research were to be done.