Aramid nanofiber filaments and related methods
AssigneeThe Regents of the University of Michigan
InventorsHenry A. Sodano, Hyun Chan Kim
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Abstract
The disclosure relates to a method for forming nanofiber-assembled filaments in which an aromatic polyamide nanofiber suspension is first formed into wet nanofiber-assembled filaments via wet-spinning and protonation in a coagulation medium including at least one proton donor along with a non-solvent for the aromatic polyamide. The wet nanofiber-assembled filaments are then drawn to reduce/remove voids in the nanofiber-assembled filaments and improve the mechanical properties of the assembled filaments. The method can be used as a recycling method for used aromatic polyamide fiber/filament materials in which the recycled filaments have high/good mechanical properties relative to virgin filament materials.
Claims25
A method for forming nanofiber-assembled filaments, the method comprising:
- providing a nanofiber suspension comprising aromatic polyamide nanofibers dispersed therein, wherein (i) the nanofiber suspension comprises a suspension medium comprising water, deprotonated aromatic polyamide nanofibers as the aromatic polyamide nanofibers, a water-miscible solvent for the deprotonated aromatic polyamide nanofibers, and a base, and (ii) the water-miscible solvent comprises at least one of dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and methyl ethyl ketone (MEK);
- wet-spinning the nanofiber suspension into a coagulation medium comprising at least one non-solvent for the aromatic polyamide nanofibers and at least one proton donor, thereby forming wet nanofiber-assembled filaments in the coagulation medium;
- optionally washing the wet nanofiber-assembled filaments;
- drawing the wet nanofiber-assembled filaments, thereby reducing or removing voids in the nanofiber-assembled filaments;
- optionally drying the wet nanofiber-assembled filaments, thereby forming dry nanofiber-assembled filaments;
- and
- optionally annealing the dry nanofiber-assembled filaments, thereby forming annealed nanofiber-assembled filaments.
A method for forming nanofiber-assembled filaments, the method comprising:
- providing a nanofiber suspension comprising aromatic polyamide nanofibers dispersed therein, wherein (i) the nanofiber suspension comprises a suspension medium comprises water, deprotonated aromatic polyamide nanofibers as the aromatic polyamide nanofibers, a water-miscible solvent for the deprotonated aromatic polyamide nanofibers, and a base, and (ii) the water-miscible solvent comprises at least one of dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and methyl ethyl ketone (MEK);
- and
- wet-spinning the nanofiber suspension into a coagulation medium comprising at least one non-solvent for the aromatic polyamide nanofibers and at least one proton donor, thereby forming wet nanofiber-assembled filaments in the coagulation medium;
- wherein:
- the coagulation medium comprises at least one of (i) an acid as the at least one proton donor, and (ii) an aprotic solvent as the non-solvent for the aromatic polyamide nanofibers.
A method for forming nanofiber-assembled composite filaments, the method comprising:
- providing a nanofiber suspension comprising (i) aromatic polyamide nanofibers dispersed therein, and (ii) an additional polymeric material dissolved or dispersed in the suspension, wherein (a) the nanofiber suspension comprises a suspension medium comprising water, deprotonated aromatic polyamide nanofibers as the aromatic polyamide nanofibers, a water-miscible solvent for the deprotonated aromatic polyamide nanofibers, and a base, and (b) the water-miscible solvent comprises at least one of dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and methyl ethyl ketone (MEK);
- and
- wet-spinning the nanofiber suspension into a coagulation medium comprising at least one non-solvent for the aromatic polyamide nanofibers and optionally at least one proton donor, thereby forming wet nanofiber-assembled composite filaments in the coagulation medium.
A method for recycling aromatic polyamide fibers, the method comprising:
- forming a nanofiber suspension from one or more of an aromatic polyamide fiber, fabric, or filament material by converting the aromatic polyamide fiber, fabric, or filament material to aromatic polyamide nanofibers dispersed in a nanofiber suspension, wherein (i) the nanofiber suspension comprises a suspension medium comprising water, deprotonated aromatic polyamide nanofibers as the aromatic polyamide nanofibers, a water-miscible solvent for the deprotonated aromatic polyamide nanofibers, and a base, and (ii) the water-miscible solvent comprises at least one of dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and methyl ethyl ketone (MEK);
- wet-spinning the nanofiber suspension into a coagulation medium comprising at least one non-solvent for the aromatic polyamide nanofibers and at least one proton donor, thereby forming wet nanofiber-assembled filaments in the coagulation medium;
- optionally washing the wet nanofiber-assembled filaments;
- drawing the wet nanofiber-assembled filaments, thereby reducing or removing voids in the nanofiber-assembled filaments;
- optionally drying the wet nanofiber-assembled filaments, thereby forming dry nanofiber-assembled filaments;
- and
- optionally annealing the dry nanofiber-assembled filaments, thereby forming annealed nanofiber-assembled filaments.
Dependencies are inferred from the claim text.