The bright side of cellulosic hibiscus sabdariffa fibres: towards sustainable materials from the macro- to nano-scale

Abstract

Plant fibres are helically twisted cellulosic materials that are bonded together by lignin and hemicellulose matrices. Their physical, mechanical, and chemical properties depend enormously on the relative proportions of their chemical constituents, the atmospheric conditions, the age of the plant, and the collection time, among other factors. Hibiscus sabdariffa fibre is obtained by processing the stems or seeds of the Hibiscus sabdariffa plant (Hibiscus sabdariffa L.), which is an evergreen plant that is grown in almost all tropical regions of the world. Polymer composites or membranes developed utilizing plant fibres exhibit astonishing chemical resistance and mechanical and thermal properties, which are attributed to their chemical constituents, low density, and structural dimensions. However, further augmentation of the pre-existing properties of plant-fibre-fortified bio-composites can be achieved via enhancing the bonding between the hydrophilic plant fibres and the hydrophobic matrix, which should be possible by tailoring the surfaces of the plant fibres. In the present article, the methods and techniques employed for the extraction of Hibiscus sabdariffa fibre and its conversion into micro- and nano-forms are discussed. In addition, the effects of numerous surface tailoring strategies on the physicomechanical, thermal, water uptake, and humidity absorption characteristics of Hibiscus sabdariffa fibre have been surveyed to establish surface tailoring strategies and fibre dimension modification as feasible processes for producing useful Hibiscus sabdariffa fibres to address industrial needs. The surface-tailored plant macro-/micro-/nanofibres can fortify bio-composites and thus improve the utilization of Hibiscus sabdariffa fibre as a dependable and reasonable material for industrial purposes, which in turn may help to meet worldwide targets for creating and developing biomaterials for a better future.