Dimensionally stable, leak-free graphite substrate
A method for preparing resin-impregnated graphite articles, including providing a sheet of compressed particles of exfoliated graphite having two major surfaces; impregnating the sheet with a first resin system to form a resin-impregnated sheet; surface treating the resin-impregnated sheet to form at least one structure on at least one of the major surfaces of the sheet to form a surface treated sheet; and treating the sheet with a second resin system.
1. A dimensionally stable, leak-free fluid flow plate for an electrochemical fuel cell, comprising a sheet of compressed particles of exfoliated graphite having two major surfaces, at least one of the major surfaces having at least one groove or channel formed thereon, the sheet having a first resin system and a second resin system incorporated thereinto, wherein the first resin system comprises a polybenzoxazine resin and the second resin system comprises a methacrylate resin, further wherein the first resin system impregnated into the sheet at a level of about 5% to about 35% by weight and the second resin system applied to the surface of the sheet at a level of about 0.05% and about 10% by weight.
2. The article of claim 1 , wherein the first resin system further comprises an epoxy resin.
3. The article of claim 1 , wherein the second resin system applied to the sheet at a level of about 0.1% to about 9% by weight.
4. The article of claim 3 , wherein the second resin system further comprises a dye.
5. A method for preparing resin-impregnated graphite articles, comprising:
a. providing a sheet of compressed particles of exfoliated graphite having two major surfaces;
b. impregnating the sheet with a first resin to form a resin-impregnated sheet, wherein the first resin comprises a polybenzoxazine resin impregnated into the sheet at a level of about 5% to about 35% by weight;
c. treating the resin-impregnated sheet with a second resin, wherein the second resin comprises a methacrylate resin, further wherein the second resin applied to the sheet at a level of about 0.1% to about 9% by weight; and
d. surface treating the resin-impregnated sheet to form at least one channel or groove on at least one of the major surfaces of the sheet to form a surface treated sheet prior to treatment with the second resin.
6. The method of claim 5 , wherein the first resin further comprises an epoxy resin.
7. The method of claim 5 , wherein the methacrylate resin applied to the sheet at a level of about 0.2% and about 6% by weight.
8. The method of claim 5 , wherein the second resin further comprises a free radical initiator.
9. The method of claim 8 , wherein the free radical initiator comprises a substituted azonitrile compound.
10. The method of claim 5 , wherein the second resin further comprises a dye.
11. The method of claim 5 , wherein the first resin at least partially cured prior to surface treating of the resin-impregnated sheet.
12. The method of claim 5 , wherein surface treating of the resin-impregnated sheet comprises embossing a channel along the surface of the resin-impregnated sheet.