Apart from these distinct spinning techniques employed for the fabrication of filaments, factors such as process parameters, chemical modification/treatments, mechanical stretching or twisting, and electric or magnetic field alignment can also be used to tune the properties of the resultant filament 10, 11, 12. In dry-spinning, the solvent is evaporated using hot air following extrusion from the nozzle, whereas, in melt-spinning, the filaments are prepared by extrusion of the suspension followed by cooling 9. The wet-spinning process begins with extruding suspension through a nozzle of the desired diameter into a coagulation or precipitation bath to form filaments 8. All spinning procedures commence with dissolving the polymer precursor to obtain a spinning dope (suspension) which is then extruded through a spinneret (nozzle). Electrospinning is a widely reported method whereby fiber fabrication occurs under an electric field 7. Wet-spinning, dry-spinning, and dry-jet wet-spinning are a few different solvent-spinning techniques 5, 6. Solvent-spinning and melt-spinning are the most prevalent methods for producing synthetic and cellulose-based filaments. The bottom-up approach focuses on the fabrication processes of NCLF, which include a wide range of spinning techniques. Thus, extending it to a large-scale continuous filament, the so-called nanocellulose long filament (NCLF), is challenging. Although the isolation of CNFs is quite simple, its size is too small, limiting its applications for fibers and composites. The top-down strategy emphasizes the isolation of CNFs, CNCs, and CNPs from natural sources by utilizing several chemical and mechanical methods 4. The two primary strategies considered for preparing CNFs are top-down and bottom-up. CNFs possess unique characteristics such as biodegradability, biocompatibility, flexibility, lightweight, and a high aspect ratio, rendering them suitable for a wide range of applications such as energy storage, medicine, food packaging, cosmetics, structural composites, and healthcare 1, 3. Examples of these forms include cellulose microfibers (CMFs), cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and cellulose nanoparticles (CNPs) 1, 2. Nanocellulose exists in different forms depending on their geometric characteristics, such as length and diameter. Nanosized cellulose, called nanocellulose, has proven to be a high-performance building block of nature 1. The advancement of nanotechnology has accelerated the extraction of cellulose fibers at the nanoscale, revolutionizing the field of cellulose research. Moreover, an AC electric field and mechanical stretching are introduced to highlight the versatility of the proposed integrated wet-spinning system, thereby enhancing the mechanical properties of NCLFs.Ĭellulose has been utilized in the form of fiber or its derivatives for more than a century. At the spinning speed of 510 cm/min, a production rate of 4.99 m/min is achieved, five times higher than the productivity of the former pilot system (0.92 m/min). The spinning speed is increased to improve NCLF productivity, and the bobbin winder speeds, collector bobbin winder location, and NCLF drying conditions are tuned. Herein, we present an integrated wet-spinning system by incorporating a few previously researched filament production techniques to mass fabricate high-strength continuous NCLFs. Despite the widespread availability of numerous filament production processes, the cost-effective and continuous fabrication of high-strength NCLFs on a large scale remains an ongoing challenge. The continuous production of high-strength nanocellulose long filaments (NCLFs) is critical in natural fiber-reinforced polymer composites.
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