Electric field-assisted wet spinning to fabricate strong, tough, and continuous nanocellulose long fibers

High-Strength, Multifunctional, and Long Nanocellulose Hybrid Fibers Coated with Esterified Poly(vinyl alcohol)–Citric Acid–Lignin Resin

“…The coagulation of Fine CNF in the citric acid bath during the wet spinning process was governed by an ion-exchange phenomenon. 20 As citric acid was used as the cross-linker in H-PCL resin, employing it for the coagulation process can result in better cross-linking between the NCLF and the H-PCL resin. The wet spinning system was installed in a cleanroom to maintain a constant temperature and humidity to preserve the reproducibility of NCLFs.…”

“…The 2 wt % Fine CNF suspension was spun into the coagulation bath containing 0.2 wt % citric acid. The coagulation of Fine CNF in the citric acid bath during the wet spinning process was governed by an ion-exchange phenomenon . As citric acid was used as the cross-linker in H-PCL resin, employing it for the coagulation process can result in better cross-linking between the NCLF and the H-PCL resin.…”

“…These explicit aspects of CNFs paved the way for their broad applications in natural fiber-reinforced polymer composites (NFRPCs). − However, various concerns with employing CNFs as a composite reinforcement include their short length, inherent hydrophilicity, and weak interfacial bonding. , In fabricating strong and tough long fiber with CNFs, their alignment is essential, which requires sophisticated and diverse alignment processes, but most of these techniques are costly and complex, making industrial scaling of the long fiber fabrication difficult . Owing to the molecular structure of CNF and its inherent strength, a wide range of approaches for fiber fabrication such as wet spinning, cold drawing, wet stretching, self-assembly, and electrospinning are currently effective in the field of research. − In addition, external electric and magnetic field alignment approaches were investigated to achieve well-aligned CNFs with superior mechanical performance. − …”

Engineering strong man-made cellulosic fibers: a review of the wet spinning process based on cellulose nanofibrils

“…Secondly, as reported by many studies, the CNF concentration needs to be above 1 wt% or even 2 wt%, and a re-concentration process is always needed. 58,[61][62][63]105 Note that most of those studies are using a normal type of homogenization facility which can only produce CNFs with a concentration <1 wt%. Such a reconcentration process is always carried out through centrifugation, 58,[61][62][63]105 vacuum evaporation (often with rotary facility) 31,116 or (ultra-)filtration.…”

“…58,[61][62][63]105 Note that most of those studies are using a normal type of homogenization facility which can only produce CNFs with a concentration <1 wt%. Such a reconcentration process is always carried out through centrifugation, 58,[61][62][63]105 vacuum evaporation (often with rotary facility) 31,116 or (ultra-)filtration. 117 The first two are time-consuming and energy-intensive; while the last one cannot be performed in conventional filtering machines because: (1) CNF suspensions at high concentrations are very viscous and require extremely high driving pressure, and (2) CNFs with a thin width/diameter can either pass through the filter (with a big mesh size) too easily or block the filter (with a small mesh size) to significantly reduce the flux.…”