Method of making graphitic carbon-carbon composite

1. A method of making a graphitic carbon-carbon composite from thermosetting polymer resin comprising the steps of:

a) infusing bis-Schiff base resin into a carbon fiber reinforcement to form an uncured resin embedded composite, the bis-Schiff base resin comprising the structure of Formula (I):

wherein:

R comprises at least one aromatic moiety,

X comprises an aromatic moiety, an aliphatic moiety, or a hydrogen and

X′ comprises an aromatic moiety, an aliphatic moiety, or a hydrogen;

b) positioning the uncured resin embedded composite on a substrate under a vacuum enclosure;

c) curing the carbon fiber reinforcement embedded with bis-Schiff base resin at a first elevated temperature under vacuum to form a polymer matrix composite;

d) heating the polymer matrix composite at a second elevated temperature under inert atmosphere to form a porous carbon-carbon composite;

e) re-infusing bis-Schiff base resin into the porous carbon-carbon composite resulting from step (d) and curing the newly infused bis-Schiff base resin under vacuum at a third elevated temperature to generate a reinfused porous carbon-carbon composite;

f) heating the reinfused porous carbon-carbon composite resulting from step (e) at a fourth elevated temperature under inert gas to densify the resulting reinfused porous carbon-carbon composite from step (e) and form the graphitic carbon-carbon composite;

wherein the second elevated temperature and/or at least one instance of the fourth elevated temperature is greater than 1800° C.

2. The method of claim 1 wherein the carbon fiber reinforcement is unidirectional fibers, woven fabric, braided fabric, or 3D fiber preform.

3. The method of claim 1 wherein the uncured resin embedded composite is a prepreg.

4. The method of claim 1 wherein the infusion step of step (a) is conducted with a pressure differential between the carbon fiber reinforcement and a source of the bis-Schiff base resin.

5. The method of claim 1 wherein the infusion step of step (e) is conducted with a pressure differential between the porous carbon-carbon composite and a source of the bis-Schiff base resin.

6. The method of claim 1 wherein the carbon material density of the graphitic carbon-carbon composite is greater than 1.7 g/cm 3 .

7. The method of claim 1 wherein the steps (e) and (f) are repeated at least one time with the graphitic carbon-carbon composite previously generated in step (f) provided in lieu of the porous carbon-carbon composite in step (e).

8. The method of claim 7 wherein the apparent density of the graphitic carbon-carbon composite is greater than 1.7 g/cm 3 .

9. The method of claim 1 , wherein the vacuum enclosure comprises a vacuum bag.

10. The method of claim 1 , wherein the vacuum applied in step (c) is 25 inches of Hg of greater.

11. The method of claim 1 , wherein the vacuum applied in step (e) is 25 inches of Hg of greater.

12. The method of claim 1 , wherein the second elevated temperature and/or at least one instance of the fourth elevated temperature is at least 2200° C.

13. The method of claim 1 , where the bis-Schiff base resin has a viscosity below 100,000 cP at 170° C.

14. The method of claim 1 , wherein the char yield of the bis-Schiff resin in the graphitic carbon-carbon composite is greater than 50%.

15. The method of claim 1 , wherein the carbon fiber reinforcement is heat treated prior to infusion of the bis-Schiff base resin, heat treating the carbon fiber reinforcement comprising heating the carbon fiber reinforcement in an inert atmosphere to at least 2000° C.

16. The method of claim 1 , wherein the first elevated temperature and the third elevated temperature are substantially the same.

17. The method of claim 1 , wherein the char yield of the bis-Schiff resin in the graphitic carbon-carbon composite is greater than 78%.