High velocity dry spinning of nanofibrillated cellulose (CNF) filaments on an adhesion controlled surface with low friction
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A new process for preparing thin cellulose nanofibril (CNF) filaments (thickness of 16 µm) was investigated by utilizing the dry spinning approach. In the process, CNF hydrogel was extruded through a fine nozzle onto an adhesion controlled capstan (drum) with low friction (slippery surface) at a speed of up to 11 m/s. The utilized capstan enables excellent line speed control when the slippery surface is applied, and prevents drying shrinkage of the spun filaments. The mechanical properties of prepared filaments can be optimized with the stretch ratio, the ratio of the speed of the drum surface, and the CNF jet flow. The developed method allows for manufacturing thin CNF filaments with an elevated spinning rate in a more controlled manner.
KeywordsCNF Filament Spinning Dry-spinning SEM Tensile strength
The work started as part of the Design Driven Value Chains in the World of Cellulose project (DWOC) funded by Tekes the Finnish Funding Agency for Innovation and continued through VTT’s internal project funded with the aid of a government grant. The authors appreciate the help from Panu Lahtinen and Minna Hakalahti for providing the nanocellulose samples, as well as for valuable discussions with Jari Vartiainen and Heikki Pajari about slippery surfaces.
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