A state-of-the-art review focusing on the significant techniques for naturally available fibers as reinforcement in sustainable bio-composites: Extraction, processing, purification, modification, as well as characterization study

Eco-friendly bio-active materials designed from available natural resources have been signified a big challenge in the past few decades. Nevertheless, the deficiency of the most essential knowledge regarding the effective processing of starting materials which has been used to fabricate the targeted bio-polymeric composites framework is considered a foremost encounter. However, natural cellulosic fibers (generally extracted from different parts of plants like bast/bark, leaf, steam) have received more attention from researchers, due to their outstanding physiochemical, thermomechanical, morphological properties and eco-friendly nature/sustainability. Basically, the features of natural fibers hinge on the proper preparation and the effective modification process. Conversely, the main problem of natural fiber is its hydrophilic nature while polymeric matrix are hydrophobic thus it is urgent to reduce the hydrophilic nature of natural fibers by conducting various significant chemical modification techniques so as to improve the overall quality of fibers as reinforcement in sustainable biocomposite. Therefore, it will be proposed with a detailed overview focusing on the various notable process of modifications and characterization methods of the cellulosic fibers in this review. We also summarize the significant important findings from the earlier literature and the effects of treatments on the overall properties of the fibers being emphasized.