Braid-reinforced composites and processes for their preparation
Resin compositions of the invention are capable of effectively impregnating conventional braid forms and comprise at least one relatively low viscosity resin and at least one viscosity modifier. Hot-melt processing of such resin compositions and others imparts additional advantages and processing efficiencies when preparing braid-reinforced composites.
1. A resin composition for preparation of a braid-reinforced composite, the composition comprising: an essentially uncured initial resin comprising at least one thermosetting resin and, optionally, at least one thermoplastic resin; an amount of at least one curative for the thermosetting resin, which amount of curative effectuates cure of the resin composition within about 45 to about 60 minutes when heated to 120° C.; and at least one viscosity modifier; wherein viscosity of the initial resin in the resin composition is less than about 6 Pa-s when tested at 25° C.; wherein the resin composition exhibits Bingham plastic fluid behavior; wherein the resin composition is capable of impregnating a braid form using hot-melt processing; and wherein the resin composition is capable of remaining impregnated throughout the braid form, without partial curing, until final cure of the resin composition to form the braid-reinforced composite.
2. The resin composition of claim 1 , wherein the initial resin has a viscosity of about 2.5 Pa·s to about 4.5 Pa·s when tested at 25° C.
3. The resin composition of claim 1 , wherein the initial thermosetting resin comprises an epoxy resin.
4. The resin composition of claim 1 , wherein the viscosity modifier comprises a thixotropic agent, a nanomaterial, or a combination thereof.
5. The resin composition of claim 1 , wherein the viscosity modifier comprises a thixotropic agent.
6. The resin composition of claim 1 , wherein the viscosity modifier comprises fumed silica.
7. The resin composition of claim 1 , wherein the viscosity modifier comprises a nanomaterial.
8. The resin composition of claim 1 , wherein the viscosity modifier comprises a carbon nanomaterial.
9. The resin composition of claim 1 , wherein the initial thermosetting resin comprises at least one resin based on diglycidyl ether of Bisphenol F.
10. The resin composition of claim 1 , further comprising at least one elastomeric toughening component.
11. The resin composition of claim 1 , wherein the resin composition has a glass transition temperature of less than about 200° C. as measurable using Differential Scanning calorimetry.
12. The resin composition of claim 1 , wherein the initial resin has a viscosity of less than about 5 Pa·s (50 Poise) when tested at 25° C.
13. The resin composition of claim 1 , further comprising at least one detackifying resin selected from waxes, fatty acids, and other release agents.
14. The resin composition of claim 1 , wherein the initial resin consists of resin based on diglycidyl ether of Bisphenol F.
15. The resin composition of claim 1 , wherein the initial resin consists of thermosetting resin.
16. The resin composition of claim 1 , wherein the resin composition has relatively low tack.
17. The resin composition of claim 1 , wherein the resin composition is essentially flow-stable during cure.
18. A braid-reinforced resin composition comprising:
a braid form;
the resin composition of claim 1 impregnated throughout the braid form.
19. The braid-reinforced resin composition of claim 18 , wherein the resin composition is essentially uncured.
20. A braid-reinforced composite comprising the braid-reinforced resin composition of claim 18 , wherein the resin composition is cured.
21. A method of preparing a braid-reinforced composite, comprising:
providing the resin composition of claim 1 in one or multiple parts;
impregnating the braid form with the resin composition of claim 1 to form a braid-reinforced resin composition; and
curing the braid-reinforced resin composition to form the braid-reinforced composite.
22. The method of claim 21 , wherein the resin composition is impregnated on the braid form using resin injection hot-melt processing.
23. The method of claim 22 , wherein the resin composition is pre-soaked with the resin composition prior to resin injection.
24. The method of claim 21 , wherein diameter of the braid form is locally increased during impregnation of the braid form.
25. The method of claim 21 , wherein the resin composition remains essentially uncured until fully curing the braid-reinforced resin composition to form the braid-reinforced composite.
26. The resin composition of claim 1 , wherein the at least one curative for the thermosetting resin effectuates cure of the resin composition when heated to 100° C.
27. The resin composition of claim 1 , wherein about 2% to about 7% by weight of the resin composition comprises one or more viscosity modifiers.
28. The resin composition of claim 1 , wherein the at least one curative for the thermosetting resin comprises an aliphatic amine curative.
29. The resin composition of claim 1 , wherein the braid form is a tubular braid.
30. The braid-reinforced resin composition of claim 18 , wherein the braid form is a tubular braid.