Method of making carbon fibers from lignin
A method of making a carbon fiber includes heat treating a lignin precursor absent an active ingredient in an inert atmosphere to raise the glass transition temperature (Tg) of the precursor by at least five (5%) percent, forming a lignin precursor having an increased Tg (High Tg Lignin). The High Tg Lignin can be spun into a fiber. The fiber may then be stabilized to form a thermoset fiber. The time period for stabilizing the fiber is less than one hundred (100) hours.
1. A method of making a carbon fiber comprising:
a. heat treating a lignin in an inert atmosphere at a sufficient temperature for a sufficient period of time to raise the glass transition temperature (Tg) of the lignin by at least twenty percent, thereby forming a lignin precursor having an increased Tg (High Tg Lignin);
b. spinning the High Tg Lignin into a fiber; and
c. stabilizing the fiber for a period of time of less than one hundred hours under sufficient conditions to thereby form a thermoset fiber.
2. The method of claim 1 wherein the period of time comprises less than fifty hours.
3. The method of claim 1 wherein the temperature of said heat treating comprises at least 100° C. to no more than 400° C.
4. The method of claim 3 wherein the temperature comprises at least 200° C.
5. The method of claim 1 further including reacting the High Tg Lignin with furfuryl alcohol in the presence of a Lewis acid or a Bronsted acid.
6. A method of making a lignin carbon fiber precursor comprising:
heat treating a lignin in an oxidizing atmosphere at a sufficient temperature for a sufficient period of time to raise the glass transition temperature (Tg) of the lignin by at least twenty percent but not above the combustion temperature of the lignin, thereby forming a lignin precursor having an increased Tg (High Tg Lignin).
7. A method of claim 6 wherein the temperature of said heat treating comprises at least 100° C. to no more than 400° C.
8. A method of claim 6 further including reacting the High Tg Lignin with furfuryl alcohol in the presence of a Lewis acid or a Bronsted acid.
9. A method of making a carbon fiber precursor comprising:
heat treating a lignin in an inert atmosphere at a sufficient temperature for a sufficient period of time to raise the glass transition temperature (Tg) of the lignin by at least twenty percent, thereby forming a lignin precursor having an increased Tg (High Tg Lignin).
10. The method of claim 6 further comprising spinning the High Tg Lignin into a fiber and stabilizing the fiber for a period of time of less than one hundred hours under sufficient conditions to thereby form a thermoset fiber.
11. The method of claim 9 the heating treating occurs at a temperature below 400° C.
12. The method of claim 9 further comprising reacting either the lignin or the High Tg Lignin with furfuryl alcohol in the presence of a Lewis Acid or a Bronsted Acid.
13. The method of claim 1 wherein a ramp rate of the stabilizing from room temperature to 100° C. comprises 3° C./minute.
14. The method of claim 1 wherein the Tg of the High Tg Lignin comprises more than 100° C.
15. The method of claim 10 wherein a ramp rate of the stabilizing from room temperature to 100° C. comprises 3° C./minute.
16. The method of claim 6 wherein the Tg of the High Tg Lignin comprises more than 100° C.
17. The method of claim 9 further comprising stabilizing a fiber derived from the lignin precursor, a ramp rate of the stabilizing from room temperature to 100° C. comprises 3° C./minute.
18. The method of claim 9 wherein the Tg of the High Tg Lignin comprises more than 100° C.
19. The method of claim 18 wherein a fiber derived from the lignin precursor comprises a thermoset fiber.