Method of spinning fibres or extrusion, and the products obtained
The invention relates to a continuous, scalable and parallelizable method for preparing strong and stiff fibers (filaments) or films. The fiber or film is prepared by utilizing hydrodynamically induced alignment of the constituents of a dispersion in combination with surface-charge controlled gel transition to produce fibers with a high degree of alignment of the constituents (polymer(s), fibrils etc). The invention also relates to the fibers or films so formed.
1. Method of spinning fibres or extrusion, comprising
a) Injection of a central flow dispersion comprising long-chained polymer(s) or non-spherical particles into a central flow channel of a reaction chamber;
b) Acceleration of the central flow in the reaction chamber by at least two opposite, aligning flow streams, essentially perpendicular to the central flow, whereby the long-chained polymer(s) or non-spherical particles are aligned in the flow direction; and
c) Gelling of the aligned long-chained polymer(s) or non-spherical particles, through diffusion of salt, chelating agent or acid contained in the aligning flow streams, into the aligned long-chained polymer(s) or non-spherical particles, followed by coagulation of the gel string obtained, and/or
d) Polymerization of a polymerizable component contained in the central flow dispersion; and
e) Drying of the fibre obtained.
2. Method according to claim 1 , wherein the central flow is constituted by multiple streams.
3. Method according to claim 1 , comprising at least two reaction chambers in parallel.
4. Method according to claim 3 , wherein the number of reaction chambers in parallel is 3-30.
5. Method according to claim 1 , wherein the long chained polymer(s) or nonspherical particles in (a) are nanocellulose, a polymeric protein, or carbon nano tubes.
6. Method according to claim 1 , wherein the flow dispersion in (a) additionally comprises nano clay or graphene.
7. Method according to claim 1 , wherein the flow dispersion in (a) has a concentration of 0.01-10% (w/w) of long-chained polymer(s) or non-spherical particles.
8. Method according to claim 1 , wherein the aligning flow streams are constituted by water, and the central flow comprises a polymerizable component.
9. Method according to claim 1 , wherein in (c) the gelling salt, chelating agent or acid is chosen from the group consisting of organic acids, inorganic acids, water soluble complexing agents, organic salts, and inorganic salts.
10. Method according to claim 1 , wherein in (c) the coagulation proceeds inside the reaction chamber by addition of a coagulating agent or outside of the reaction chamber in a separate coagulating bath.
11. Method according to claim 1 , wherein the coagulation is effected by immersion of the gel string into acetone or alcohol.
12. Method according to claim 1 , wherein in (d) the polymerization is effected in the reaction chamber through light, radiation, ultrasound, or heat.
13. Method according to claim 1 , wherein the reaction chamber(s) have rectangular cross section(s).
14. Method according to claim 1 , wherein the central flow dispersion is swirled or oscillated, either before step (b), or in step (b) by additional, oblique flow(s).
15. Method according to claim 14 , wherein the flow dispersion is swirled or oscillated by a change of geometry in the reaction chamber.
16. Method according to claim 1 , wherein the fibre obtained is carbonized.
17. Method according to claim 1 , wherein the diffusion of salt, chelating agent or acid contained in the aligning flow streams comprises diffusion of ions of the salt, chelating agent or acid contained in the aligning flow streams.