Contamination of the ecosystem from plastics is the most prominent concern of current times. Natural materials like plant-based fibers from cellulose, hemp, sisal, etc., are preferred and being looked upon as better alternatives.Cellulose, being biocompatible and biodegradable, possesses appreciable properties. Its nanoscale form, called as nanocellulose, can be extracted from agricultural residue and lignocellulosic biomass through different chemomechanical techniques. Chemical methods include alkaline treatment, chemical bleaching, acid hydrolysis, and TEMPO mediated oxidation, whereas highpressure homogenization, grinding, cryogenic crushing, and ultrasonication are the mechanical methods used for the isolation and extraction of nanocellulose. This review presents a comprehensive analysis of various processing and extraction methods used for nanocellulose. The review also brings an insight into nanocellulose-polymer based composites including their mechanical, biological, thermal, and physical properties. A detailed discussion on nature, morphology, size, and other parameters through different characterization techniques is also presented in this review. Finally, the applications of nanocellulose in biotechnology, biomedical, mechanical, material science, chemical, and electronics engineering have also been discussed.
K E Y W O R D Sbio-composites, characterization, chemo-mechanical methods, extraction, nanocellulose
| INTRODUCTIONUrge to go green has led to a shift toward eco-friendly or green materials. This approach aims at reducing the emissions of greenhouse gases to safeguard the environment at a global level. Eco-friendly and naturally occurring materials are being mostly focused for such purposes. This is done in order to reduce the dependence and for the replacement of synthetically available materials. The naturally occurring materials offer several advantages like sustainability, low cost, better resistance toward wear, low toxicity, high modulus of elasticity, and large specific area with better mechanical and biological properties. The advantages of incorporating the use of eco-friendly or green materials are shown in Figure 1.Natural fibers obtained from plants and other sources are being used to develop materials with greater interests and scope. Widely used natural fibers include cotton, flax, silk, sisal, jute, and alpaca, etc. Composites made from natural fibers are called as bio-composites. The fibers can be utilized as a segment of composite materials, where their orientation impacts the overall properties. In these
