Curable epoxy system
A curable epoxy system useful in the production of composites capable of being used in various industries, including, for example, the aerospace industry. In particular, the present disclosure relates to a curable epoxy system comprising (i) an epoxy component selected from bisphenol C diglycidyl ether, one or more derivatives of bisphenol C diglycidyl ether, and combinations thereof, and (ii) 9,9-bis(4-amino-3-chlorophenyl)fluorene.
1. A curable epoxy system, comprising: an epoxy component selected from bisphenol C diglycidyl ether, one or more derivatives of bisphenol C diglycidyl ether, and combinations thereof; 9,9-bis(4-amino-3-chlorophenyefluorene; and at least one curing agent capable of facilitating curing of the epoxy component, other than 9,9-bis(4-amino-3-chloropenyl)fluorene; wherein the epoxy component and 9,9-bis(4-amino-3-chlorophenyl)fluorene are present in the curable epoxy system in amounts such that a stoichiometric weight ratio of the epoxy component to 9,9-bis(4-amino-3-chlorophenyl)fluorene is from 1:1 to 1.4:1; and wherein the curable epoxy system has a cure enthalpy of less than 300 J/g and is capable of producing a cured material having a glass transition temperature greater than 190° C.
2. The curable epoxy system of claim 1 , wherein the at least one curing agent is selected from an amine curing agent, an anhydride curing agent, a polyol curing agent, and combinations thereof.
3. The curable epoxy system of claim 1 , wherein the at least one curing agent is selected from 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4′diamino-diphenylmethane, 4,4′-diaminodiphenyl sulphone, 4-aminophenyl sulphone, 3,3′-diaminodiphenyl sulphone, 4,4′-methylenebis(3-chloro-2,6-diethylaniline), 4,4′-methylenebis(2,6-diethylaniline), and combinations thereof.
4. The curable epoxy system of claim 1 , further comprising at least one additive selected from a thermoplastic particle, a flexibilizer, a polyamide toughening agent, an accelerator, a core shell rubber, a wetting agent, a flame retardant, a pigment or dye, a plasticizer, a UV absorber, a viscosity modifier, and combinations thereof.
5. The curable epoxy system of claim 1 , wherein the combined amount of the epoxy component, 9,9-bis(4-amino-3-chlorophenyl)fluorene, and the at least one curing agent is greater than 40 wt % based on the weight of the curable epoxy system.
6. A method of curing the curable epoxy system of claim 1 , comprising heating the curable epoxy system at a set cure temperature in a range from 100° C. to 220° C. for a time sufficient to produce an at least partially cured material.
7. The method of claim 6 , wherein the set cure temperature is attained by heating the curable epoxy system at a cure ramp rate in a range of from 0.5° C. per minute to 25° C. per minute from ambient temperature.
8. The method of claim 6 , wherein the difference between the set cure temperature and the maximum temperature reached in the center of the curable epoxy system is less than 20° C.
9. An at least partially cured material obtained by the method of claim 6 .
10. A prepreg comprising a fibrous material in contact with the curable epoxy system of claim 1 .
11. A method of producing a fiber reinforced composite structure, comprising contacting a fibrous material with the curable epoxy system of claim 1 to form a curable fiber reinforced epoxy system; and curing the curable fiber reinforced epoxy system to form a fiber reinforced composite structure.
12. The method of claim 11 , wherein the step of curing the curable fiber reinforced epoxy system comprises heating the curable fiber reinforced epoxy system at a set cure temperature in a range of from 100° C. to 220° C. for a time sufficient to produce an at least partially cured fiber reinforced composite structure.
13. The method of claim 12 , wherein the set cure temperature is attained by heating the curable fiber reinforced epoxy system at a cure ramp rate in a range of from 0.5° C. per minute to 25° C. per minute from ambient temperature.
14. The method of claim 12 , wherein the difference between the set cure temperature and the maximum temperature reached in the center of the curable fiber reinforced epoxy system is less than 20° C.
15. The method of claim 11 , wherein the curable fiber reinforced epoxy system has a thickness of at most 60 mm.
16. A fiber reinforced composite structure obtained by the method of claim 11 .
17. An aerospace component comprising the fiber reinforced composite structure of claim 16 .